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{{short description|Home computers produced by Amstrad}}
[[Image:Amstrad CPC464.jpg|right|thumb|370px|Amstrad CPC 464, with CTM644 colour monitor]]
{{Use dmy dates|date=July 2020}}
{{Use British English|date=April 2020}}
{{Infobox computer
| Name = Amstrad CPC
| logo = Amstrad CPC logo.svg
| Photo = Amstrad CPC464.jpg
| caption =
| Type = [[Personal computer]]
| Developer = [[Amstrad]]
| Released = {{Start date and age|1984}}
| Discontinued = {{Start date and age|1990}}
| generation = Third
| unitssold = 3 million
| Processor = [[Zilog Z80]]A @ 4 [[Hertz|MHz]]
| Memory = 64 or 128&nbsp;[[Kilobyte|KB]],<ref>{{BDprefix|p=b}}</ref> expandable to 576&nbsp;KB
| Media = [[Data cassette|Compact Cassette]], 3-inch [[floppy disk]]s
| Graphics = [[Motorola 6845]] or compatible, custom [[gate array]]
| Display = 160×200 pixels with 16 colours, 320×200 pixels with 4 colours, 640×200 pixels with 2 colours
| Input = [[keyboard (computing)|Keyboard]]
| Connectivity =
| OS = [[AMSDOS]] with [[Locomotive BASIC]] 1.0 or 1.1; [[CP/M]] 2.2 or 3.0
| Baseprice =
| sound = [[AY-3-8912]], 3-voices, 8-octaves
}}


The '''Amstrad CPC''' was a series of [[8-bit]] [[home computer]]s produced by [[Amstrad]] during the [[1980s]] and early [[1990s]]. CPC stood for 'Colour Personal Computer', although it was possible to purchase a CPC with a [[green screen]] (GT65/66) as well as with the standard colour screen (CTM640).
The '''Amstrad CPC''' (short for "Colour Personal Computer") is a series of [[8-bit]] [[home computer]]s produced by [[Amstrad]] between 1984 and 1990. It was designed to compete in the mid-1980s home computer market dominated by the [[Commodore 64]] and the [[ZX Spectrum]]; it successfully established itself primarily in the United Kingdom, France, Spain, and the German-speaking parts of Europe.
The first machine, the CPC 464 was introduced in [[1984]]. It was designed to be a direct competitor to the [[Commodore 64]] and [[Sinclair Research Ltd|Sinclair]] [[ZX Spectrum]] systems.


The series spawned a total of six distinct models: The ''[[Amstrad CPC 464|CPC 464]]'', ''CPC 664'', and ''CPC 6128'' were highly successful competitors in the European home computer market. The later ''464 plus'' and ''6128 plus'', intended to prolong the system's lifecycle with hardware updates, were considerably less successful, as was the attempt to repackage the ''plus'' hardware into a game console as the ''GX4000''.
Outwardly, the most distinguishing features of Amstrad's offering were the matte black console case with sharp corners and narrowly rectangular form factor (the latter due to the built-in [[Compact audio cassette|cassette tape]] deck ('''CPC 464''') or [[Floppy_drive#The_3-inch_compact_floppy_disk|floppy disk drive]] ('''CPC 664''' and '''CPC 6128'''), the keyboard's distinctly coloured special keys (all the non-typewriter-standard keys), and the unique power supply hookup with one lead going from the console to the monitor (or RF modulator) and one lead going the other way. A television could be used with an optional adapter.


The CPC models' hardware is based on the [[Zilog Z80A]] [[CPU]], complemented with either 64 or 128&nbsp;KB of [[Random-access memory|RAM]]. Their computer-in-a-keyboard design prominently features an integrated storage device, either a compact cassette deck or 3-inch floppy disk drive. The main units were only sold bundled with either a colour, green-screen or monochrome monitor that doubles as the main unit's power supply.<ref name="464 Manual">CPC464 User Manual, p. 11, Amstrad Consumer Electronics Plc.</ref> Additionally, a wide range of first and third-party hardware extensions such as external disk drives, printers, and memory extensions, was available.
==The Amstrad CPC sold as a "complete system"==
[[Image:Amstrad CPC Advert.png|right|thumb|UK advert for the Amstrad&nbsp;CPC&nbsp;464]]
Amstrad initially promoted the CPC as being an improvement on the competing [[ZX Spectrum]] and [[C64]] because it was a '''complete system''' - including everything required to use the machine in one box. Compared to a C64 or a ZX Spectrum, the Amstrad CPCs shipped with their own monitor, had a built in tape recorder or floppy disk drive and even a small loudspeaker. This marketing gave a more "professional" appeal to the Amstrad CPC by marketing it in the same way as business-oriented systems, rather than gaming or home oriented ones.


The CPC series was pitched against other home computers primarily used to play video games and enjoyed a strong supply of game software. The comparatively low price for a complete computer system with dedicated monitor, its high-resolution monochrome text and graphic capabilities and the possibility to run [[CP/M]] software also rendered the system attractive for business users, which was reflected by a wide selection of application software.
As a late entrant to the European 8-bit market, the CPC range never achieved the sales volume of either the ZX Spectrum or the C64, but the advantages of a proper typewrite-style keyboard and integrated tape or floppy drive saw it obtain considerable market share in the late 80s. Despite strong competition in the UK, it became the most popular and best-selling computer in France at this time.


During its lifetime, the CPC series sold approximately three million units.<ref name="Amstrad Product Archive">{{cite web |title=Amstrad Product Archive |url=http://www.amstrad.com/products/archive/index.html |access-date=25 September 2009 |archive-url=https://web.archive.org/web/20080509185726/http://www.amstrad.com/products/archive/index.html |archive-date=9 May 2008 |url-status=dead }}</ref>
==The CPC family==
[[File:Schneider CPC6128 white.jpg|thumb|300px|right|The Schneider CPC 6128 was a Schneider-branded version of the Amstrad CPC 6128, and very similar in appearance.]]<!-- Right-aligned image occupying otherwise unused space beside contents list -->
===The Amstrad CPC 464, 472, 664, 6128===
The original CPC was sold in the following configurations:


==Models==
*'''CPC 464''' &ndash; [[Compact audio cassette|Tape deck]], 64 [[kilobyte|KB]] [[random access memory|RAM]], square-edged keyboard
*'''CPC 472''' &ndash; Tape deck, 72K RAM (although the extra 8K of RAM cannot be used); produced in small numbers for the Spanish market to avoid a legal ruling requiring that all computers with 64 KB or less RAM must be localized to the Spanish language, including the keyboard and screen messages.
*'''CPC 664''' &ndash; [[Floppy_drive#The_3-inch_compact_floppy_disk|3" Floppy disk drive]], 64K RAM, bowed keyboard; short-lived model, quickly replaced by the better-specified 6128
*'''CPC 6128''' &ndash; 3" Floppy disk drive, 128K RAM (accessed using [[bank switching]]), more PC-like keyboard


===The original range===
External disk drives such as the DDI-1/FD-1 were available for the 464. A cassette adapter was available for the 664 and 6128. All 128K models were [[backward compatibility|backward compatible]] with the 64K variants. A third-party hardware addon, the [[Multiface]], allowed backup of most tape software to disk.
The philosophy behind the CPC series was twofold, firstly the concept was of an "all-in-one", where the computer, keyboard and its data storage device were combined in a single unit and sold with its own dedicated display monitor. Most home computers at that time such as [[ZX Spectrum]] series, [[Commodore 64]], and [[BBC Micro]] relied on the use of the domestic [[television]] set and a separately connected [[tape recorder]] or [[disk storage|disk drive]]. In itself, the all-in-one concept was not new, having been seen before on business-oriented machines and the [[Commodore PET]].


Secondly, Amstrad founder [[Alan Sugar]] wanted the machine to resemble a "real computer, similar to what someone would see being used to check them in at the airport for their holidays",<ref name="Newkey-Burden2010">{{cite book|author=Chas Newkey-Burden|title=Sir Alan Sugar: The Biography|url=https://books.google.com/books?id=vW5MQQAACAAJ|year=2010|publisher=John Blake|isbn=978-1-84454-891-0}}</ref> and for the machine to not look like "a pregnant calculator"<ref name="Sugar2010">{{cite book|author=Alan Sugar|title=What You See Is What You Get: My Autobiography|url=https://books.google.com/books?id=nSLXRgAACAAJ|year=2010|publisher=Pan Macmillan|isbn=978-0-230-74933-7}}</ref> – in reference presumably to the [[ZX81]] and [[ZX Spectrum]] with their low cost, membrane-type keyboards.
Most games and software targeted the 64K RAM 464 and 664 models. Only a handful of titles exclusively targeted the 128K machines.


[[File:Cpc464.computer.750pix.jpg|thumb|Children playing ''[[Paperboy (video game)|Paperboy]]'' on the CPC 464 in 1988]]
The memory layout of the system allowed the CPCs to run [[CP/M|CP/M 2.2]] and CP/M software adapted especially for the machines was not uncommon. An Amstrad-specific variant of CP/M 3.0 (aka CP/M Plus) was developed for the 6128 and used in later years.


===West Germany: Schneider CPC 464, 664 and 6128===
====CPC 464====
{{Main|Amstrad CPC 464}}
Amstrad's German partner company '''Schneider''' produced its own models of the CPC 464, 664 and 6128. These machines had grey keys in place of the Amstrad coloured alternatives and an industry standard [[Micro ribbon|Centronics]] port in place of the expansion edge connector but were otherwise identical at the hardware level. Documentation and case labels were translated into German.
The CPC 464 was one of the most successful computers in Europe and sold more than two million units.<ref>{{cite web|title=OLD-COMPUTERS.COM : The Museum|url=http://www.old-computers.com/museum/computer.asp?c=84|website=www.old-computers.com|access-date=27 June 2016|archive-url=https://web.archive.org/web/20190325035533/http://www.old-computers.com/Museum/computer.asp?c=84|archive-date=25 March 2019|url-status=dead}}</ref>


The CPC 464 featured 64&nbsp;KB RAM and an internal [[cassette deck]]. It was introduced in June 1984 in the UK. Initial suggested retail prices for the CPC 464 were £249.00/[[Deutsche Mark|DM]]899.00 with a green screen and £359.00/DM1398.00 with a colour monitor. Following the introduction of the CPC 6128 in late 1985, suggested retail prices for the CPC 464 were cut by £50.00/DM100.00.
===East Germany: KC compact===
Like most other computers of the era, the CPC inspired a clone in the [[Eastern bloc]], the '''[[KC compact]]''' made in [[East Germany]] using Russian and East German components.


In 1990, the 464plus replaced the CPC 464 in the model line-up, and production of the CPC 464 was discontinued.
The machine differed from a CPC visually with a different style of case, external power supply and (optional and even more scarce than the main device) external 5.25" 'Robotron' disc drive. Unlike the Amstrad models it could be used with a television screen out of the box. It ran BASIC 1.1 and a CP/M 2.6 clone, the German speaking MicroDOS. It had 64K RAM built in and an additional 64K RAM was provided with the external disc/tape drive adapter.


====CPC 664====
The Z80 processor was replaced with a U 880 (which is 100% bug-compatible), and some proprietary Amstrad I/O chips replaced with clones based on the Z8536. This clone machine was around 95% compatible with the original.
[[File:Schneider 664 en.jpg|thumb|A ''CPC 664'' main unit (German Schneider-brand variant)]]


The CPC 664 features 64&nbsp;KB RAM and an internal 3-inch floppy disk drive. It was introduced on 25 April 1985 in the UK.<ref name="Special Feature: Happy Birthday!">{{cite magazine |title=Special Feature: Happy Birthday! |magazine=[[Popular Computing Weekly]] |date=1 May 1987 |pages=14–18 (18) |url=https://archive.org/details/popular-computing-weekly-1987-05-01/page/n17}}</ref> Initial suggested retail prices for the CPC 664 were £339.00/DM1198.00 with a green screen and £449.00/DM1998.00 with a colour monitor.
===The CPC 5512===
The "CPC 5512" was a non-functional [[hoax|fake]] concocted by a French magazine; the specifications included 512K RAM, a 5.25" floppy disk drive, and GEM on a CPC 6128 clone.


After the successful release of the CPC 464, consumers were constantly asking for two improvements: more memory and an internal disk drive. For Amstrad, the latter was easier to realise. At the deliberately low-key introduction of the CPC 664, the machine was positioned not only as the lowest-cost disk system but even the lowest-cost CP/M 2.2 machine. In the Amstrad CPC product range the CPC 664 complemented the CPC 464 which was neither discontinued nor reduced in price.<ref>The CPC664, ''Amstrad Computer User'' May 1985, P. 42-46.</ref>
===PLUS models===
In 1990 Amstrad introduced the "Plus" series which tweaked the hardware in many ways and added a [[Cartridge (electronics)|cartridge]] slot to all models. Most improvements were to the video display which saw an increase in palette to 4096 colours and gained a capacity for [[Sprite (computer graphics)|hardware sprites]]. Splitting the display into two separate windows and [[pixel]] scrolling both became full supported hardware features although both were possible on the non-"Plus" hardware using clever programming of the existing [[Motorola 6845]].


Compared to the CPC 464, the CPC 664's main unit has been significantly redesigned, not only to accommodate the floppy disk drive but also with a redesigned keyboard area. Touted as "ergonomic" by Amstrad's promotional material, the keyboard is noticeably tilted to the front with [[MSX]]-style cursor keys above the numeric keypad. Compared to the CPC 464's multicoloured keyboard, the CPC 664's keys are kept in a much quieter grey and pale blue colour scheme.
An automatic DMA transfer system for feeding the sound chip was also added but the sound chip itself remained unchanged. Additionally, the BASIC command set for disc access was improved.


The back of the CPC 664 main unit features the same connectors as the CPC 464, with the exception of an additional 12V power lead. Unlike the CPC 464's cassette tape drive that could be powered off the main unit's 5V voltage, the CPC 664's floppy disk drive requires an additional 12V voltage. This voltage had to be separately supplied by an updated version of the bundled green screen/colour monitor (GT-65 and CTM-644 respectively).
A cut down CPC+ without the keyboard nor support for non-cartridge media was released simultaneously as the [[Amstrad_GX4000|'''GX4000''']] [[video game console]].


The CPC 664 was only produced for approximately six months. In late 1985, when the CPC 6128 was introduced in Europe, Amstrad decided not to keep three models in the line-up, and production of the CPC 664 was discontinued.<ref name="InterviewPerry">{{cite web|title=Interview de M. Roland Perry |lang=fr|publisher=Amstrad Forever|url=http://amstrad.cpc.free.fr/article.php?sid=38|access-date=2 April 2010|url-status=dead|archive-url=https://web.archive.org/web/20110720221414/http://amstrad.cpc.free.fr/article.php?sid=38|archive-date=20 July 2011}}</ref>
These models did not do very well in the marketplace, failing to attract any substantial third party support. The 8-bit technology behind the CPC was starting to look a little out of date by 1990 and users resented the substantial price hike for cartridge games compared to their tape and disc counterparts.


==Hardware description==
====CPC 6128====
[[File:Amstrad CPC6128, keyboard removed.jpg|thumb|CPC 6128 main circuit board.]]
All CPC models were based on a [[Zilog Z80]] processor clocked at 4 MHz. Because a common pool of RAM is shared with the video circuits, the Z80 may only make a memory accesses every four cycles - which has the effect of rounding all instruction cycle lengths up to the next multiple of four.
The CPC 6128 features 128&nbsp;KB RAM and an internal 3-inch floppy disk drive. Aside from various hardware and [[firmware]] improvements, one of the CPC 6128's most prominent features is the compatibility with the CP/M+ operating system that rendered it attractive for business uses.


The CPC 6128 was released on 13 June 1985 and initially only sold in the US.<ref name="Special Feature: Happy Birthday!"/> Imported and distributed by Indescomp, Inc. of Chicago, it was the first Amstrad product to be sold in the United States, a market that at the time was traditionally hostile towards European computer manufacturers.<ref>''Amstrad Computer User'', "User News...", August 1985, p. 7.</ref> Two months later, on 15 August 1985, it arrived in Europe<ref name="Special Feature: Happy Birthday!"/> and replaced the CPC 664 in the CPC model line-up. Initial suggested retail prices for the CPC 6128 were US$699.00/£299.00/DM1598.00 with a green screen and US$799.00/£399.00/DM2098.00 with a colour monitor.
The system came with 64 KB or 128 KB of RAM depending on the model (capable of being expanded to 512k). The machines also featured a standard 9-pin [[Atari]]-style [[joystick]] socket which was able to take two joysticks via a splitter.


In 1990, the 6128plus replaced the CPC 6128 in the model line-up, and production of the CPC 6128 was discontinued.
===Video (graphics): modes, outputs===
Underlying the CPCs video output was the [[Motorola 6845]] address generator. This chip was connected to a pixel generator that supported 4 bpp, 2 bpp and 1 bpp output (bpp = [[color depth|bits per pixel]]). The address generator was clocked at a constant rate so the 4 bpp display generated half as many pixels as the 2 bpp and a quarter as many as the 1 bpp.


===The ''plus range''===
The [[Read-only memory|ROM]] featured three built-in display resolutions but many others could be achieved by reprogramming the 6845.
In 1990, confronted with a changing home computer market, Amstrad decided to refresh the CPC model range by introducing a new range variantly labelled ''plus'' or ''PLUS'', ''1990'', or ''CPC+ range''. The main goals were numerous enhancements to the existing CPC hardware platform, to restyle the casework to provide a contemporary appearance, and to add native support of cartridge media. The new model palette includes three variants, the ''464plus'' and ''6128plus'' computers and the ''GX4000'' video game console. The "CPC" abbreviation was dropped from the model names.


The redesign significantly enhanced the CPC hardware, mainly to rectify its previous shortcomings as a gaming platform. The redesigned video hardware allows for 16 [[Sprite (computer graphics)|hardware sprites]]<ref>{{cite web |title=Original Arnold V Specs |url=https://www.cpcwiki.eu/index.php/Original_Arnold_V_Specs |website=CPCWiki |access-date=8 January 2025}}</ref> and soft scrolling, with a colour palette extended from a maximum of 16 colours (plus separately definable border) at one time from a choice of 27, increased to a maximum of 31 (16 for background and 15 for hardware sprites) out of 4096. The enhanced sound hardware offers automatic [[DMA transfer]], allowing more complex sound effects with a significantly reduced processor overhead. Other hardware enhancements include the support of analogue joysticks, 8-bit printers, and [[ROM cartridge]]s up to 4 [[megabit|Mbit]]s.
The standard video modes were:
*'''Mode 0''': '''160×200''' pixels with 16 colors (4 [[color depth|bpp]])
*'''Mode 1''': '''320×200''' pixels with 4 colors (2 bpp)
*'''Mode 2''': '''640×200''' pixels with 2 colors (1 bpp)


The new range of models was intended to be completely [[backwards compatible]] with the original CPC models. Its enhanced features are only available after a deliberately obscure unlocking mechanism has been triggered, thus preventing existing CPC software from accidentally invoking them.<ref name="ArnoldVSpec">{{cite web|title=Arnold "V" Specification 1.4|last=Lawson|first=Cliff|publisher=Amstrad|url=http://web.ukonline.co.uk/cliff.lawson/arnold5.htm|archive-url=https://web.archive.org/web/20001118214900/http://web.ukonline.co.uk/cliff.lawson/arnold5.htm|archive-date=18 November 2000 |url-status=dead}}</ref>
A colour [[palette]] of 27 colors was supported, derived from [[RGB]] colour space with each component assigned as either off, half on or on. The later '''Plus''' models extended this to 4096 colours and added support for hardware sprites.


Despite the significant hardware enhancements, many viewed it as outdated, being based on an 8-bit CPU, and it failed to attract both customers and software producers who were moving towards systems such as the [[Amiga]] and [[Mega Drive]] which was launched a few short months after the plus range. The plus range was a commercial failure,<ref>[[Retro Gamer]] issue 83, From the Archives: Radical Software</ref> and production was discontinued shortly after its introduction in 1990.
This hardware compares well with the other 8-bit computers. In particular the CPC lacks the colour clash of the ZX Spectrum and clever programming of the 6845 could produce [[overscan]], different resolutions (although with the same pixel density) and smooth pixel scrolling.


====464 plus, 6128 plus====
The machine lacked either an [[RF modulator|RF TV]] or [[composite video]] output and instead shipped with a proprietary 5-pin [[DIN connector]] intended for use solely with the supplied Amstrad monitor. An external adapter for RF TV was available to be bought separately.
[[File:6128plus es.jpg|thumb|A ''6128 plus'' main unit (with Spanish keyboard layout)]]
The ''464 plus'' and ''6128 plus'' models were intended as "more sophisticated and stylish" replacements of the CPC 464 and CPC 6128. Based on the redesigned plus hardware platform, they share the same base characteristics as their predecessors: The 464 plus is equipped with 64&nbsp;KB RAM and a cassette tape drive, the 6128 plus features 128&nbsp;KB RAM and a 3" floppy disk drive. Both models share a common case layout with a keyboard taken over from the CPC 6128 model, and the respective mass storage drive inserted in a case breakout.


In order to simplify the [[Electromagnetic compatibility|EMC]] screening process, the edge connectors of the previous models have been replaced with micro-ribbon connectors as previously used on the German Schneider CPC 6128. As a result, a wide range of extensions for the original CPC range are connector-incompatible with the 464 plus and 6128 plus. In addition, the 6128plus does not have a tape socket for an external tape drive.
The five-pin DIN connector is capable of driving a [[SCART]] television with a correctly wired lead.


The plus range is not equipped with an on-board ROM, and thus the 464 plus and the 6128 plus do not contain a firmware. Instead, Amstrad provided the firmware for both models via the [[read only memory|ROM]] extension facility, contained on the included ''Burnin' Rubber and Locomotive BASIC'' cartridge. This resulted in reduced hardware localization cost (only some select key caps and case labels had to be localized) with the added benefit of a rudimentary [[copy protection]] mechanism (without a firmware present, the machine itself could not copy a game cartridge's content).<ref name="ArnoldVSpec"/> As the enhanced ''V4'' firmware's structural differences causes problems with some CPC software directly calling firmware functions by their memory addresses, Amstrad separately sold a cartridge containing the original CPC 6128's ''V3'' firmware.<ref name="GrimwareCartridges">{{cite web|title=Amstrad System Cartridges|publisher=grimware.org|url=http://www.grimware.org/doku.php/documentations/hardware/amstrad.cartridge.released|archive-url=https://web.archive.org/web/20100201131141/http://www.grimware.org/doku.php/documentations/hardware/amstrad.cartridge.released|url-status=dead|archive-date=1 February 2010|access-date=22 March 2010}}</ref>
===Audio (sound)===
The CPC used the [[General Instruments AY-3-8912]] [[sound chip]], providing three channels, each configurable to generate square waves, white noise or both. A small array of hardware volume envelopes are available.


Both the 464 plus and the 6128 plus were introduced to the public in September 1990. Initial suggested retail prices were {{GBP|229}}/{{currency|1990|code=FRF}} with a monochrome monitor and {{GBP|329}}/{{currency|2990|code=FRF}} with a colour monitor for the 464 plus, and {{GBP|329}}/{{currency|2990|code=FRF}} with a monochrome monitor and {{GBP|429}}/{{currency|3990|code=FRF}} with a colour monitor for the 6128plus.<ref>Paris in the Spring, ''Amstrad Action'' Issue 60, September 1990, P. 34-36</ref>
Output was provided in mono by a small (4 [[Metre#SI_multiples|cm]]) built-in loudspeaker with volume control, driven by an unusually powerful [[amplifier]]. [[Stereophonic sound|Stereo]] output was provided through a 3.5mm [[headphones]] jack, not present on some early CPC464 models. In those models, what looked like a standard 3.5" headphone jack was actually used for connecting an external tape recorder, although later models used a five-pin DIN connector for the same purpose.


====GX4000====
Playback of [[digital sampling|digital sound sample]]s at a resolution of a little better than 5-bit, as heard on the title screen of the game ''[[RoboCop (videogame)|RoboCop]]'', was possible through clever programming of the sound chip. This trick was very processor intensive and hard to combine with any other processing.
[[File:Amstrad-GX4000-Console-Set.jpg|thumb|The Amstrad GX4000]]{{main|Amstrad GX4000}}


Developed as part of the ''plus range'', the GX4000 was Amstrad's short-lived attempt to enter the video game consoles market. Sharing the plus range's enhanced hardware characteristics, it represents the bare minimum variant of the range without a keyboard or support for mass storage devices.<ref name="ArnoldVSpec"/> It came bundled with 2 [[paddle controller]]s and the racing game ''Burnin' Rubber''.
===The 3" floppy disk drives===
[[Image:Compact Floppy.jpg|right|thumbnail|150px| The CF has a harder casing than a 3&frac12;" floppy; the metal door is opened by a sliding plastic tab on the right side.]]


===Special models and clones===
Amstrad's idiosyncratic choice of [[Hitachi, Ltd.|Hitachi's]] 3" floppy disk drive, when the rest of the PC industry was moving to [[Sony]]'s 3.5" format, is often claimed to be due to Amstrad bulk-buying a large consignment of 3" drive units in [[Asia]]. The cheapest drive (built-in in later models) was a single-sided 40-track unit that required the user to physically remove and flip the disk to access both sides. Each side had its own independent write-protect switch. The sides were termed "A" and "B", with each one holding 180KB (178KB in [[AMSDOS]] format) for a total of 360KB per disc.


====CPC 472====
The interface with the drives was a NEC 765 [[Floppy disk controller|FDC]], used for the same purpose in the IBM [[PC/XT]], [[PC/AT]] and [[PS/2]] machines. Many of its features were unused in order to cut costs, namely [[DMA]] transfers and support for [[single density]] disks; they were formatted as [[double density]] using [[Modified frequency modulation]].
[[File:472 es.jpg|thumb|CPC 472]]
During the August holidays of 1985, Spain briefly introduced an import tax of 15&nbsp;000 pesetas ({{€|90.15}}) on computers containing 64&nbsp;KB or less of RAM (Royal Decree 1215/1985<ref>{{Cite web|url=https://www.boe.es/buscar/doc.php?id=BOE-A-1985-15514|title=BOE.es - BOE-A-1985-15514 Real Decreto 1215/1985, de 17 de julio, por el que se modifican determinadas subpartidas del arancel de Aduanas.|website=www.boe.es |lang=es}}</ref> and 1558/1985<ref>{{Cite web|url=https://www.boe.es/buscar/doc.php?id=BOE-A-1985-18847|title=BOE.es - BOE-A-1985-18847 Real Decreto 1558/1985, de 28 de agosto, por el que se aclara el alcance del mínimo específico introducido en la subpartida 84.53.B.II del Arancel de Aduanas, por el Real Decreto 1215/1985.|website=www.boe.es |lang=es}}</ref>), and a new law (Royal Decree 1250/1985<ref>{{Cite web|url=https://www.boe.es/diario_boe/txt.php?id=BOE-A-1985-15611|title=BOE.es - BOE-A-1985-15611 Real Decreto 1250/1985, de 19 de junio, por el que se establece la sujeción a especificaciones técnicas de los terminales de pantalla con teclado, periféricos para entrada y representación de información en equipo de proceso de datos.|website=www.boe.es |lang=es}}</ref>) mandated that all computers sold in Spain must have a Spanish keyboard. To circumvent this, Amstrad's Spanish distributor ''Indescomp'' (later to become ''Amstrad Spain'') created and distributed the ''CPC 472'', a modified version of the CPC 464. Its main differences are a small additional daughter board containing a CPC 664 ROM chip and an 8&nbsp;KB memory chip, and a keyboard with a [[ñ]] key (although some of them were temporarily manufactured without the ñ key). The sole purpose of the 8&nbsp;KB memory chip (which is not electrically connected to the machine, so consequently rendered unusable) is to increase the machine's total memory specs to 72&nbsp;KB in order to circumvent the import tax. Some months later, Spain joined the [[European Communities]] by the [[Treaty of Accession 1985]] and the import tax was suppressed, so Amstrad added the ñ key for the 464 and production of the CPC 472 was discontinued.<ref name="CPCWikiCPC472">{{cite web|title=CPC472|publisher=CPCWiki|url=http://cpcwiki.eu/index.php/472|access-date=17 August 2011}}</ref>{{better source needed|date=September 2020}}


====KC compact====
Disks were shipped in a paper sleeve or a hard plastic case resembling a [[compact disc]] "jewel" case. The casing is thicker and more rigid than that of 3.5" diskettes and sliding metal cover to protect the media surface is internal to the casing and latched, unlike the simple external sliding cover of Sony's version (some reviews at the time reported driving over them with no problems). Because of this they were significantly more expensive than both 5.25" and 3.5" alternatives. This, combined with their low nominal capacities and their essentially proprietary nature, lead to the format being discontinued when the CPC itself was discontinued.
<!-- Section title used in redirects to this page -->
[[File:KC-compact-1.jpg|thumb|right|The Kleincomputer KC compact]]
The ''{{Interlanguage link multi|KC compact|de}}'' ("{{lang|de|Kleincomputer}}" - which means "small computer" - being a rather literal German translation of the English "microcomputer") is a clone of the Amstrad CPC built by [[East Germany]]'s ''{{lang|de|[[Volkseigene Betriebe|VEB]] Mikroelektronik Mühlhausen}}'', part of ''{{lang|de|VEB [[Kombinat Mikroelektronik Erfurt]]}}'', in October 1989. Although the machine included various substitutes and emulations of an Amstrad CPC's hardware, the machine is largely compatible with Amstrad CPC software. It is equipped with 64&nbsp;KB of memory and a CPC 6128's firmware customized to the modified hardware, including a copy of [[Locomotive BASIC]] 1.1 modified in the startup banner only. The expansion port is a [[VEB Robotron#K 1520_bus_standard|K 1520 bus]] slot. The KC compact is the last 8-bit computer introduced in East Germany.<ref name="KCCompactDocu">{{cite web|title=KC Compact Documentation|url=http://www.sax.de/~zander/kcc/kcc_bw.html|access-date=11 February 2023|archive-url=https://web.archive.org/web/20220220160912/http://www.sax.de/~zander/kcc/kcc_bw.html|archive-date=20 February 2022}}</ref> Due to the [[German reunification]] happening at the time of the release, only a very small number of systems were sold. The KC compact can be emulated by free software ''JKCEMU''.<ref>{{Cite web |title=JKCEMU - Kleincomputer-Emulator (in German) |url=http://www.jens-mueller.org/jkcemu/ |access-date=2023-03-06 |website=www.jens-mueller.org}}</ref>


====Aleste 520EX====
Apart from Amstrad's other 3" machines (the [[Amstrad PCW|PCW]] and ZX Spectrum +3), the only other computer systems to use them were mostly obscure and exotic CP/M systems such as the [[Tatung Einstein]] and [[Osborne 1|Osborne]] machines.
In 1993, [[Omsk|Omsk, Russia]] based company Patisonic released the Aleste 520EX, a computer highly compatible with the Amstrad CPC 6128.<ref>{{Cite web|url=http://www.cpcwiki.eu/index.php/Aleste_520EX|title=Aleste 520EX - CPCWiki|website=www.cpcwiki.eu}}</ref><ref>{{Cite web|url=http://aleste520.narod.ru/aleste.html|title=Aleste 520EX|website=aleste520.narod.ru}}</ref><ref>{{Cite web |url=http://zonadepruebas.org/backup/modules/smartsection/item.php?itemid=1076 |title=Spanish page |access-date=10 January 2015 |archive-url=https://web.archive.org/web/20160313034418/http://zonadepruebas.org/backup/modules/smartsection/item.php?itemid=1076 |archive-date=13 March 2016 |url-status=dead }}</ref> It could also be switched into an [[MSX]] mode. An expansion board named ''Magic Sound'' allowed to play [[Scream Tracker]] files.


{{clear}}
The data formatting of 3" disks was very similar to that of 5&frac14;" disks, and the Amstrad CPC machines were able to use 5&frac14;" drives through their "external drive" port - either one specially designed for use by the CPC or an adapted IBM-PC drive.


==Reception==
A more popular alternative was to attach an adapted IBM-PC 3&frac12;" drive for operation in either single-sided 180 KB or double-sided 360 KB mode, although with the later availability of the PARADOS Disc Operating System, 720k per disc became available.


''[[Your Computer (British magazine)|Your Computer]]'' concluded that the CPC 464 had "Superior graphics and sound, an excellent Basic coupled with a flexible operating system" and that Amstrad's target sales of 200,000 by the end of 1984 were realistic.<ref name="beesley198406">{{cite magazine | url=https://archive.org/details/your-computer-magazine-1984-06/page/n69/mode/2up | title=Review: Amstrad | magazine=[[Your Computer (British magazine)|Your Computer]] | date=June 1986 | access-date=8 January 2025 | last=Beeesley | first=Simon | pages=70-72 | volume=4 | issue=6 | publisher=[[Business Press International Ltd]] | location=Sutton, Surrey }}</ref>
===Serial port adaptor===
An official [[RS-232|RS-232-C]] [[D-subminiature|D25]] serial port adaptor was produced that attached to the expansion connector at the rear of the machine, and had a through-connector for the CPC464 disk drive or other peripherals. The adaptor came with a "''Book of Spells''" for facilitating data transfer between other systems using a proprietary [[protocol (computing)|protocol]] in the device's own ROM, as well as [[computer terminal|terminal]] software to connect to British Telecom's [[Prestel]] service. A separate version of the ROM was created for the U.S. market due to the use of the commands "SUCK" and "BLOW", which were considered unacceptable there.


A ''[[BYTE]]'' columnist in January 1985 called the CPC 464 "the closest yet to filling" his criteria for a useful home computer, including good keyboard, 80-column text, inexpensive disk drive, and support for a mainstream operating system like CP/M.<ref name="pountain198501">{{cite magazine | url=https://archive.org/stream/BYTE_Vol_10-01_1985-01_Through_The_Hourglass#page/n401/mode/2up | title=The Amstrad CPC 464 | magazine=[[Byte (magazine)|BYTE]] | date=January 1985 | access-date=9 January 2015 | last=Pountain | first=Dick | pages=401–407 | volume=10 | issue=1}}</ref>
===Similarities to the BBC Micro===
The CPC has been termed an "improved Z80 implementation of the (earlier) [[BBC Micro]]" due to similarities in [[firmware]] and hardware. Both use the Motorola 6845 video address generator and the two have very similar sound output chips - the General Instrument AY-3-8912 in the CPC provides three tone channels each optionally with added noise and the [[Texas Instruments SN76489]] in the BBC offers three tone channels and one exclusive noise channel.


==Hardware==
The BBC Micro uses an [[Intel]] 8271 floppy disc controller. The CPC uses the Intel 8272, which is similar to the 8271 but contains the addition of a double density ([[Modified Frequency Modulation|MFM]]) mode.


===Processor===
The "two cursor" BASIC editing system seen on the Amstrad CPC (whereby holding Shift and using the cursor keys moves a shadow text [[Cursor_(computers)|cursor]] allowing text to be copied from another area of the screen to the normal cursor) is a lift from [[BBC BASIC]], albeit substantially improved by allowing free movement of the normal cursor.
The entire CPC series is based on the [[Zilog Z80]]; a processor, clocked at 4&nbsp;[[Hertz|MHz]].<ref name="464 Tech spec">Technical Specification, CPC464 Service Manual, p. 2., Amstrad Consumer Electronics Plc.</ref>


In order to avoid the CPU and the video logic simultaneously accessing the shared main memory and causing video corruption ("snowing"), CPU memory access is constrained to occur on [[microsecond]] boundaries. This effectively pads every [[processing cycle|machine]] cycle to four [[clock cycle]]s, causing a minor loss of processing power and resulting in what Amstrad estimated to be an "effective clock rate" of "approximately 3.3&nbsp;MHz".<ref name="SOFT968">CPC464/664/6128 Firmware (Soft 968), Section 1</ref>
Both systems provide similar systems of full hardware abstraction through [[Operating System]] calls. This saves programs which don't require time critical hardware access from having to touch the underlying machine and provides a level of machine portability for those programs.


==Software==
===Memory===
Amstrad CPCs are equipped with either 64 (CPC 464, CPC 664, 464plus, GX4000) or 128 (CPC 6128, 6128plus)&nbsp;KB of RAM.<ref name="464 Tech spec"/><ref name="6128 Tech spec">Technical Specification, CPC6128 Service Manual, p. 31., Amstrad Consumer Electronics Plc.</ref> This base memory can be extended by up to 512&nbsp;KB using memory expansions sold by third-party manufacturers, and by up to 4096&nbsp;KB using experimental methods developed by hardware enthusiasts. Because the Z80 processor is only able to directly address 64&nbsp;KB of memory, additional memory from the 128&nbsp;KB models and memory expansions is made available using [[bank switching]].
===Built-in BASIC and operating system===
Like most home computers at the time, the CPC had its [[operating system|OS]] and a [[BASIC programming language|BASIC]] [[interpreter (computer software)|interpreter]] built in as [[read-only memory|ROM]]. It used [[Locomotive BASIC]] - a variant specifically written for the CPC hardware which as a result was faster, more comfortable and more powerful than the generic but common [[Microsoft BASIC]] used by the Commodore 64 and [[MSX]] amongst others. It was particularly notable for providing easy access to the machine's video and audio resources in contrast to the arcane [[PEEK and POKE|POKE]] commands required on some Microsoft implementations (the MSX implementation of Microsoft Basic being an exception, which even allowed for hardware sprite manipulation and collision detection).


===Other languages===
===Video===
[[File:Schneider CPC6128 with green monitor GT65, Wikipedia logo.jpg|thumb|Mode 1 image on a GT65 green monitor]]
Although it was possible to obtain compilers for Locomotive BASIC, [[C programming language|C]] and [[Pascal]] the majority of the CPC's software was written in native Z80a assembly language.
Underlying a CPC's video output is the unusual pairing of a [[Cathode Ray Tube Controller|CRTC]] ([[Motorola 6845]] or compatible) with a custom-designed [[gate array]] to generate a pixel display output. CPC 6128s later in production as well as the models from the plus range integrate both the CRTC and the gate array's functions with the system's [[Application-specific integrated circuit|ASIC]].


Three built-in display resolutions are available: 160×200 pixels with 16 colours ("Mode 0", 20 text columns), 320×200 pixels with 4 colours ("Mode 1", 40 text columns), and 640×200 pixels with 2 colours ("Mode 2", 80 text columns).<ref name="464 Tech spec"/> Increased screen size can be achieved by reprogramming the CRTC.
An interpreter for the educational language [[Logo programming language|LOGO]] was also available.


The original CPC video hardware supports a [[Palette (computing)|colour palette]] of 27 colours,<ref name="464 Tech spec"/> generated from [[RGB]] colour space with each colour component assigned as either off, half on, or on ([[List of monochrome and RGB color formats#3-level RGB|3 level RGB palette]]). The plus range extended the palette to 4096 colours, also generated from RGB with 4 bits each for red, green and blue ([[List of monochrome and RGB color formats#12-bit RGB|12-bit RGB]]).<ref name="ArnoldVSpec"/>
===Criticism of CPC software (games)===
The quality of CPC software has been sometimes criticized due to the existence of games that were simply a ZX Spectrum port, thus not measuring up to the equivalent ZX Spectrum or C64 implementations in terms of taking full advantage of the CPC capabilities.


[[File:Amstrad MP-1.jpg|thumb|Amstrad MP1 external television adapter]]
Because the CPC shared the Z80a processor with the ZX Spectrum, and could be made to run the same code using similar display modes, many game manufacturers developed games for the two systems in parallel or ported older Spectrum games, yielding products that did not take advantage of hardware scrolling or the availability of 4 and 16 colour modes. Despite this, ZX Spectrum ports did not show [[attribute clash]] on CPCs.
With the exception of the GX4000, all CPC models lack an [[RF modulator|RF television]] or [[composite video]] output and instead shipped with a 6-pin RGB [[DIN connector]], also used by Acorn computers, to connect the supplied Amstrad monitor.<ref name="464 Tech spec"/> This connector delivers a 1v p-p analogue RGB with a 50&nbsp;Hz composite sync signal that, if wired correctly, can drive a 50&nbsp;Hz [[SCART]] television. External adapters for RF television were available as a first-party hardware accessory.


===Audio===
For those actually targeting the CPC there were various problems, such as the lack of hardware support for sprites and [[scrolling]] &mdash; long time thought impossible to do smoothly in the vertical direction &mdash; and the complicated memory arrangement. This made the creation of smooth-running and colourful games harder. Titles from the late 80s onwards tended to be coded more carefully than their mid 80s counterparts, making better use of the machine's graphics capabilities, e.g. featuring smooth scrolling and better color usage.
The CPC uses the [[General Instrument AY-3-8910|General Instrument AY-3-8912]] [[sound chip]],<ref name="464 Tech spec"/> providing three channels, each configurable to generate square waves, white noise or both. A small array of hardware volume envelopes are available.


Output is provided in mono by a small (4&nbsp;cm) built-in loudspeaker with volume control, driven by an internal [[amplifier]]. [[Stereophonic sound|Stereo]] output is provided through a {{nowrap|3.5 mm}} [[headphones]] jack.
Games featuring poor scrolling, quasi-monochrome Spectrum-like graphics and sluggish controls - specially in the beginning of the CPC's commercial lifespan - were marketed alongside others including smooth scrolling, colourful graphics and crisp music and sound effects which almost rivalled those of the C64.


It is possible to play back [[sampling (signal processing)|digital sound samples]] at a resolution of approximately 5-bit by sending a stream of values to the sound chip. This technique is very processor-intensive and hard to combine with any other processing. Examples are the title screens or other non-playable scenes of games like ''[[Chase H.Q.]]'', ''[[Meltdown (8-bit video game)|Meltdown]]'', and ''[[RoboCop (1988 video game)|RoboCop]]''. The later Plus models incorporated a DMA engine in order to offload this processing.
Although the machine received more software support than most other Z80-based systems, the overall impression left is that the commercial success of the system could have been greater.


===Floppy disk drive===
That said, it is important to remark that numerous software companies from that era, such as [[Ocean Software]], [[Elite]], [[Palace Software]], [[Incentive]], [[Hewson Consultants]], [[Loriciels]] or [[Dinamic Software]] among others released quality titles on a regular basis which kept CPC users more than happy with their ''Color Personal Computer''.
[[File:Schneider CPC6128 Diskettenlaufwerk.jpg|thumb|Built-in disk drive of the CPC 6128]]
[[File:CPC6128 loading Turbo Esprit from floppy disk.flac|thumb|A CPC 6128 loading ''[[Turbo Esprit]]'' from its internal floppy drive]]
[[File:3 inch floppy disks.jpg|right|thumbnail|3-inch floppy disks used on CPC machines]]
Amstrad uses [[Panasonic|Matsushita's]] 3" floppy disk drive [ref: CPCWiki], which was compatible with [[Hitachi]]'s existing [[Compact Floppy|3" floppy disk format]].<ref name="pountain198501" /> The chosen drive (built-in for later models) is a single-sided 40-track unit that requires the user to remove and flip the disk to access the other side.<ref name="6128 Tech spec"/> Each side has its own independent write-protect switch.<ref name="6128 Tech spec"/> The sides are termed "A" and "B", with each one commonly formatted to 180&nbsp;KB (in [[AMSDOS]] format, comprising 2&nbsp;KB directory and 178&nbsp;KB storage) for a total of 360&nbsp;KB per disk.


The interface with the drives is an NEC 765 [[Floppy disk controller|FDC]], used for the same purpose in the IBM [[IBM Personal Computer XT|PC/XT]], [[PC/AT]] and [[IBM Personal System/2|PS/2]] machines. Its features are not fully used in order to cut costs, namely [[Direct memory access|DMA]] transfers and support for [[single density]] disks; they were formatted as [[double density]] using [[modified frequency modulation]].
===Notable games, with screenshots===
[[Image:Cybernoid_2_cpc.PNG|''Cybernoid 2''|170px|thumb|left]]
[[Image:Turrican_cpc.PNG|''Turrican''|180px|thumb|left]]
[[Image:Switchblade_cpc.PNG|''Switchblade''|thumb|180px|left]]
[[Image:Crafton_cpc.PNG|''Crafton&amp;Xunk''|thumb|180px|left]]
<br style="clear: left"/>


Discs were shipped in a paper sleeve or a hard plastic case resembling a [[compact disc]] "jewel" case. The casing is thicker and more rigid than that of 3.5&nbsp;inch diskettes, and designed to be mailed without any additional packaging{{Citation needed|date=December 2010}}. A sliding metal cover to protect the media surface is internal to the casing and latched, unlike the simple external sliding cover of Sony's version. They were significantly more expensive than both 5.25&nbsp;inch and 3.5&nbsp;inch alternatives. This, combined with their low nominal capacities and their essentially proprietary nature, led to the format being discontinued shortly after the CPC itself was discontinued.
==Magazines==
[[Computer magazine|Magazine]]s available for the system (at various times) included ''[[Amtix]]'', ''[[Computing With The Amstrad]]'', ''[[Amstrad Computer User]]'' (Amstrad official publication), ''[[Amstrad Action]]'', and ''[[CPC Attack]]''.


Apart from Amstrad's other 3-inch machines (the [[Amstrad PCW|PCW]] and the [[ZX Spectrum|ZX Spectrum +3]]), the few other computer systems to use them included the [[Sega]] SF-7000 and CP/M systems such as the [[Tatung Einstein]] and [[Osborne Computer Corporation|Osborne]] machines. They also found use on embedded systems.
==The Amstrad CPC vs. its competitors==
Since the Amstrad CPC was specifically built to compete with the [[ZX Spectrum]] and [[C64]], and was a relatively late entrant into the [[1980s]] 8-bit [[home computer]] market, comparisons between those computer systems were very frequent on specialized magazines but also among players themselves. Also, the three machines were practically the most [[Computer software|software]]-wise supported 8-bit home computers in history, and had a virtually identical selection of games, although with major differences in quality, technical characteristics, and platform-dependant peculiarities.


The [[Shugart bus|Shugart]]-standard interface means that Amstrad CPC machines are able to use standard 3", 3½" or 5¼" drives as their second drive. Programs such as ROMDOS and ParaDOS extend the standard AMSDOS system to provide support for double-sided, 80-track formats, enabling up to 800&nbsp;KB to be stored on a single disk.
===Amstrad vs C64===
In general, C64 users were prone to snub both other competing machines as "largely inferior", while a sort of hidden rivalry existed between ZX Spectrum and CPC users. The former considered the CPC to be just an overhyped clone of the their beloved Spectrum, while CPC users considered ZX Spectrum users as "poor, jealous cousins" who tainted their beloved machine with inferior game ports.


The 3-inch disks themselves are usually known as "discs" on the CPC, following the spelling on the machine's plastic casing and conventional [[British English spelling]].
In fact, the C64 had in general better sound, graphics and scrolling than its competitors thanks to its dedicated hardware, particularly its sound capabalities were much better, thank to the [[MOS Technology SID|SID]] chip.


===Expansion===
The C64 had a wide selection of games designed to run from floppy disks, though C64 [[Commodore 64 peripherals|floppy drive]]s were notoriously slow.
[[File:Amstrad CPC646-IMG 7196.jpg|thumb|Back of the case of a CPC 464, with the mini-jack, joystick and printer ports.]]
The hardware and firmware was designed to be able to access software provided on external ROMs. Each ROM has to be a 16&nbsp;KB block and is switched in and out of the memory space shared with the video RAM. The Amstrad firmware is deliberately designed so that new software could be easily accessed from these ROMs. Popular applications were marketed on ROM, particularly word processing and programming utility software (examples are Protext and Brunword of the former, and the MAXAM assembler of the latter type).


Such extra ROM chips do not plug directly into the CPC itself, but into extra plug-in "rom boxes" which contain sockets for the ROM chips and a minimal amount of decoding circuitry for the main machine to be able to switch between them. These boxes were either marketed commercially or could be built by competent hobbyists and they attached to the main expansion port at the back of the machine. Software on ROM loads much faster than from disc or tape and the machine's boot-up sequence was designed to evaluate ROMs it found and optionally hand over control of the machine to them. This allows significant customisation of the functionality of the machine, something that enthusiasts exploited for various purposes.<ref name="Amstrad CPC ROM expansion">{{Cite web|url=http://8bit.yarek.pl/hardware/cpc.rom/index.html|title=ROM :: Amstrad CPC -- 8bit Projects For Everyone|website=8bit.yarek.pl|access-date=1 November 2009|archive-date=8 August 2009|archive-url=https://web.archive.org/web/20090808173010/http://8bit.yarek.pl/hardware/cpc.rom/index.html|url-status=dead}}</ref> However, the typical users would probably not be aware of this added ROM functionality unless they read the CPC press, as it is not described in the user manual and was hardly ever mentioned in marketing literature. It is, however, documented in the official Amstrad firmware manual.
It also suffered from a poor built-in BASIC and was not ideal for users who wanted to learn to program in comparison to the other two machines.


The machines also feature a 9-pin [[Atari joystick port]] that will either directly take one joystick, or two joysticks by use of a splitter cable.<ref name="464 Tech spec"/>
===Amstrad vs Spectrum===
The ZX Spectrum had the simplest hardware of all three, though this meant a lower price. As a result, it suffered from [[Attribute clash|colour clash]] and the internal [[speaker]] of the 48k versions had very poor sound compared to the C64 and CPC, although later models of the ZX Spectrum shared the [[AY-3-8192]] sound chip with the CPC. Many third-party peripherials and some aspects of its built-in BASIC made it more appealing for DIY enthusiasts and hobbyist programmers.


==Peripherals==
The Amstrad CPC had better graphics capabilities than the ZX Spectrum, but a lot of its games were directly derived from their ZX Spectrum counterparts graphics-wise and sometimes sound-wise, which resulted in a long series of low quality titles which hurt the machine's reputation. Even when that was not the case, CPC titles rarely featured smooth scrolling or sprite handling due to programming complexities, although that was technically possible.


===RS232 serial adapters===
==Later Amstrad==
Amstrad issued two [[RS-232|RS-232-C]] [[D-subminiature|D25]] serial interfaces, attached to the expansion connector on the rear of the machine, with a through-connector for the CPC 464 disk drive or other peripherals.
Ultimately, the company purchased [[Sinclair Research]], discontinuing the unsuccessful [[Sinclair QL]] 16-bit business machine and relaunching the 128KB Sinclair Spectrum in "+2" and "+3" variants with better keyboards and integral storage. The case and design of these recognisably drew from the CPC series.


The original interface came with a ''Book of Spells'' for facilitating data transfer between other systems using a proprietary [[protocol (computing)|protocol]] in the device's own ROM, as well as [[computer terminal|terminal]] software to connect to British Telecom's [[Prestel]] service. A separate version of the ROM was created for the U.S. market due to the use of the commands "|SUCK" and "|BLOW", which were considered unacceptable there.
==Hardware tricks on the CPC series==


Software and hardware limitations in this interface led to its replacement with an Amstrad-branded version of a compatible alternative by [[Pace Micro Technology|Pace]]. Serial interfaces were also available from third-party vendors such as KDS Electronics and Cirkit.
===CRTC programming tricks===
Simple reprogramming of the Motorola 6845 CRTC can produce extended graphic modes, with up to 784×384 pixels, that use the [[overscan]] area. Careful timing of palette switches allows all 27 hardware colours to be visible in any display mode but due to the high CPU use, programs with variable CPU load, such as games, can be limited to change the palette once or twice per frame.


==Software==
The CRTC parameters also can be changed while a particular [[scanline]] of a frame is being draw, a technique with many applications. Changing the display mode in the middle of a frame allows to divide the screen, for example, into a colourful playing area and a high resolution score area -- like in Sorcery by [[Virgin Games]][http://www.cpczone.net/reviews/index.php?title=699]. Changing the video address in mid-frame splits the screen in two separate areas that can be hardware-scrolled independiently.


===Sound tricks===
===BASIC and operating system===
[[File:Amstrad CPC screen closeup.jpg|thumb|right|Locomotive BASIC on the Amstrad CPC 464]]
Careful programming of the AY sound chip could cause it to produce a level wave. Adjustment of the output volume would cause related adjustments in the amplitude of the wave. Using this observation it was possible to output [[Pulse-code modulation|PCM]] digital audio at better than 5-bit quality, albeit at a very high CPU cost.
Like most home computers at the time, the CPC has its [[operating system|OS]] and a [[BASIC interpreter]] built in as [[read-only memory|ROM]]. It uses [[Locomotive BASIC]] - an improved version of Locomotive Software's Z80 BASIC for the [[BBC Micro]] co-processor board. It is particularly notable for providing easy access to the machine's video and audio resources in contrast to the [[PEEK and POKE|POKE]] commands required on generic Microsoft implementations. Other unusual features include timed event handling with the AFTER and EVERY commands, and text-based windowing.


===CP/M===
The machine had an internal mechanical [[relay]] for controlling the tape recorder's motor which when switched would produce an audible click. Some software used this trick to produce "realistic" [[percussion instrument|percussion]] sounds, but usually such an abuse of the relay resulted in early failure.
[[Digital Research]]'s [[CP/M]] operating system was supplied with the 664 and 6128 disk-based systems, and the DDI-1 disk expansion unit for the 464. 64k machines shipped with CP/M 2.2 alone, while the 128k machines also include CP/M 3.1. The compact CP/M 2.2 implementation is largely stored on the boot sectors of a 3" disk in what was called "System format"; typing |CPM from Locomotive BASIC would load code from these sectors, making it a popular choice for custom game loading routines. The CP/M 3.1 implementation is largely in a separate file which is in turn loaded from the boot sector.
Much [[public domain]] CP/M software was made available for the CPC, from word-processors such as VDE to complete bulletin board systems such as ROS.

===Other languages===
Although it was possible to obtain compilers for Locomotive BASIC, [[C (programming language)|C]] and [[Pascal (programming language)|Pascal]], the majority of the CPC's software was written in native Z80 [[assembly language]]. Popular assemblers were Hisoft's Devpac, Arnor's Maxam, and (in France) DAMS. Disk-based CPC (not Plus) systems shipped with an interpreter for the educational language [[Logo programming language|LOGO]], booted from CP/M 2.2 but largely CPC-specific with much code resident in the AMSDOS ROM; 6128 machines also include a CP/M 3.1, non-ROM version. A C compiler was also written and made available for the European market through Tandy Europe, by Micro Business products.

===''Roland''===
{{mainarticle|Roland (game character)}}
In an attempt to give the CPC a recognisable mascot, a number of games by Amstrad's in-house software publisher [[Amsoft]] have been tagged with the ''[[Roland (game character)|Roland]]'' name. However, as the games had not been designed around the Roland character and only had the branding added later, the character design varies immensely, from a spiky-haired blonde teenager (''Roland Goes Digging'') to a white cube with legs (''Roland Goes Square Bashing'') or a mutant flea (''[[La Pulga|Roland in the Caves]]''). The only two games with similar gameplay and main character design are ''Roland in Time'' and its sequel ''Roland in Space''. The Roland character was named after Roland Perry, one of the lead designers of the original CPC range.

==Schneider Computer Division==
[[File:Schneider Computer Division logo (horizontal).svg|thumb|right|Schneider Computer Division logo]]
[[File:Schneider CPC6128 with green monitor GT65, keyboard.jpg|thumb|Schneider CPC 6128 with visible micro ribbon connectors at the top (back) side]]
[[File:Schneider CPC Demo Tape Präsentation Compact Cassette IMG 8687.JPG|thumb|Schneider CPC Demo Tape Presentation [[Compact Cassette]] came with the CPC 464]]
In order to market its computers in Germany, Austria, and Switzerland where Amstrad did not have any distribution structures, Amstrad entered a partnership with ''[[Schneider Rundfunkwerke AG]]'', a German company that - very much like Amstrad itself - was previously only known for value-priced audio products. In 1984, Schneider's ''Schneider Computer Division'' daughter company was created specifically for the task, and the complete Amstrad CPC line-up was branded and sold as ''Schneider CPC''.

Although they are based on the same hardware, the Schneider CPC models differ from the Amstrad CPC models in several details. Most prominently, the Schneider CPC 464 and CPC 664 keyboards featured grey instead of coloured keys, but still in the original British keyboard layout. To achieve a German "[[QWERTZ]]" keyboard layout, Schneider marketed a small software program to reassign the keys as well as sticker labels for the keys.<ref>''CPC Schneider International'' 6/85, P. 7</ref> In order to conform with stricter German [[Electromagnetic compatibility|EMC]] regulations, the complete Schneider CPC line-up is equipped with an internal metal shielding. For the same reason, the Schneider CPC 6128 features [[micro ribbon]] type connectors instead of [[edge connector]]s. Both the greyscale keyboard and the micro ribbon connectors found their way up into the design of later Amstrad CPC models.

In 1988, after Schneider refused to market Amstrad's AT-compatible computer line, the cooperation ended. Schneider went on to sell the remaining stock of Schneider CPC models and used their now well-established market position to introduce its own PC designs. With the formation of its German daughter company ''Amstrad GmbH'' to distribute its product lines including the CPC 464 and CPC 6128, Amstrad attempted but ultimately failed to establish their own brand in the German-speaking parts of Europe.<ref>CeBIT '88, ''Schneider Magazin'' 5/88, P. 6-8</ref><ref>{{cite web |title=Defunct Audio Manufacturers |url=http://audiotools.com/dead_s.html |access-date=20 September 2009}}</ref>

==Community==
The Amstrad CPC enjoyed a strong and long lifetime, mainly due to the machines use for businesses as well as gaming. Dedicated programmers continued working on the CPC range, even producing [[graphical user interface]] (GUI) operating systems such as [[SymbOS]]. Internet sites devoted to the CPC have appeared from around the world featuring forums, news, hardware, software, programming and games. CPC [[Computer magazine|Magazines]] appeared during the 1980s including publications in countries such as Britain, France, Spain, Germany, [[Denmark]], Australia, and [[Greece]]. Titles included the official [[Amstrad Computer User]] publication,<ref name="CPC UK magazines">{{cite web|title=CPC UK Magazines |publisher=Nicholas Campbell |url=http://users.durge.org/~nich/cpcmags/ |archive-url=https://web.archive.org/web/20011031154629/http://users.durge.org/~nich/cpcmags/ |url-status=dead |archive-date=31 October 2001 |access-date=6 May 2008 }}</ref> as well as independent titles like ''[[Amstrad Action]]'',<ref name="CPC UK magazines"/> ''[[Amtix!]]'',<ref name="CPC UK magazines"/> ''Computing with the Amstrad CPC'',<ref name="CPC UK magazines"/> ''[[CPC Attack]]'',<ref name="CPC UK magazines"/> Australia's ''The Amstrad User'', France's ''Amstrad Cent Pour Cent'' and ''Amstar''. Following the CPC's end of production, Amstrad gave permission for the CPC ROMs to be distributed freely as long as the copyright message is not changed and that it is acknowledged that Amstrad still holds copyright, giving [[emulator]] authors the possibility to ship the CPC firmware with their programs.<ref name="Lawson emulation">{{cite web|last=Lawson|first=Cliff|title=Lawson emulation|publisher=Cliff Lawson|url=http://web.ukonline.co.uk/cliff.lawson/cpchomec.htm|access-date=6 May 2008|archive-url=https://web.archive.org/web/20080510131526/http://web.ukonline.co.uk/cliff.lawson/cpchomec.htm|archive-date=10 May 2008|url-status=dead}}</ref>

==Influence on other Amstrad machines==
Amstrad followed their success with the CPC 464 by launching the [[Amstrad PCW]] word-processor range, another Z80-based machine with a 3" disk drive and software by [[Locomotive Software]]. The PCW was originally developed to be partly compatible with an improved version of the CPC (''ANT'', or Arnold Number Two - the CPC's development codename was Arnold).<ref>{{Cite web |url=https://www.theregister.co.uk/2014/02/12/archaeologic_amstrad_cpc_464/ |title=You're NOT fired: The story of Amstrad's amazing CPC 464 |last=Smith |first=Tony |date=12 February 2014 |website=www.theregister.co.uk |language=en |access-date=2018-12-20}}</ref><ref>{{Cite news |url=https://www.pressreader.com/uk/retro-gamer/20171228/284185106163072 |title=The CPC that never was |date=28 December 2017 |work=[[Retro Gamer]]}}</ref> However, Amstrad decided to focus on the PCW, and the ANT project never came to market.

On 7 April 1986, Amstrad announced it had bought from [[Sinclair Research]] "...the worldwide rights to sell and manufacture all existing and future Sinclair computers and computer products, together with the Sinclair brand name and those intellectual property rights where they relate to computers and computer-related products."<ref>{{Cite web|url=https://www.crashonline.org.uk/28/news.htm|title=CRASH 28 - News|website=www.crashonline.org.uk}}</ref> which included the [[ZX Spectrum]], for £5 million. This included Sinclair's unsold stock of [[Sinclair QL]]s and Spectrums. Amstrad made more than £5 million on selling these surplus machines alone. Amstrad launched two new variants of the Spectrum: the [[ZX Spectrum +2]], based on the ZX Spectrum 128, with a built-in [[compact audio cassette|tape]] drive (like the CPC 464) and, the following year, the [[ZX Spectrum +3]], with a built-in [[floppy disk]] drive (similar to the CPC 664 and 6128), taking the 3" discs that Amstrad CPC machines used.

== Production Timeline ==
<timeline>
ImageSize = width:800 height:auto barincrement:25
PlotArea = left:115 bottom:110 top:20 right:10
Alignbars = justify
DateFormat= dd/mm/yyyy
Period = from:01/01/1984 till:30/06/1992
TimeAxis = orientation:horizontal format:yyyy
Legend = orientation:vertical position:bottom columns:4
ScaleMajor= increment:1 start:1984
ScaleMinor= increment:2 start:1984

Colors =
id:CPC_464 value:green legend:CPC_464
id:CPC_472 value:limegreen legend:CPC_472
id:CPC_664 value:blue legend:CPC_664
id:CPC_6128 value:red legend:CPC_6128
id:Lines value:black legend:Vertical_lines_are_Product_Announcements
id:Plus_GX4000 value:orange legend:Plus_range_and_GX4000

LineData =
at:11/04/1984 color:green layer:back
at:01/04/1985 color:blue layer:back
at:01/06/1985 color:red layer:back
at:01/09/1990 color:orange layer:back
at:30/06/1992 color:black layer:back

BarData =
bar:CPC464 text:"CPC 464"
bar:CPC472 text:"CPC 472"
bar:CPC664 text:"CPC 664"
bar:CPC6128 text:"CPC 6128"
bar:464Plus text:"464 Plus"
bar:6128Plus text:"6128 Plus"
bar:GX4000 text:"GX 4000"

PlotData =
width:10 textcolor:black align:left anchor:from shift:(10,-4)
bar:CPC464 from:01/06/1984 till:31/08/1990 color:CPC_464
bar:CPC472 from:15/09/1985 till:01/01/1986 color:CPC_472
bar:CPC664 from:01/04/1985 till:30/09/1985 color:CPC_664
bar:CPC6128 from:01/06/1985 till:31/08/1990 color:CPC_6128
bar:464Plus from:01/09/1990 till:30/06/1992 color:Plus_GX4000
bar:6128Plus from:01/09/1990 till:30/06/1992 color:Plus_GX4000
bar:GX4000 from:01/09/1990 till:30/06/1992 color:Plus_GX4000

width:3 textcolor:black align:left anchor:from shift:(10,-4)
</timeline>


==See also==
==See also==
* [[Amstrad CPC character set]]
* [[Amstrad CP/M Plus character set]]
* [[List of computer system emulators#Amstrad CPC|List of Amstrad CPC emulators]]
* [[List of Amstrad CPC games]]
* [[List of Amstrad CPC games]]
* [[GX4000]]
* [[Amstrad PCW]], CP/M wordprocessor/personal computer range
* [[SymbOS]] (multitasking operating system)
* [[CP/M]]

* [[Sinclair Research]]
==Notes and references==
* [[ZX Spectrum]]
{{Reflist}}


==External links==
==External links==
{{Commons}}
* [http://www.amstrad.com/ Amstrad official website]
* [http://www.cpczone.net/ CPC Zone]
* [http://www.cpcwiki.eu/ CPC-Wiki] (CPC specific Wiki containing further information)
* [http://andercheran.aiind.upv.es/~amstrad/ The Unofficial Amstrad WWW Resource]
* [http://www.cpctech.org.uk/ Unofficial Amstrad WWW Resource]
* [http://www.cpc-imperium.de/ Amstrad CPC Imperium / Amsoft Headquarter]
* [http://www.futureos.de/ New OS for the CPC]
* [http://tacgr.emuunlim.com/ The Amstrad CPC Games Resource]
* [http://www.amstrad-esp.com/ Amstrad ESP]
* [http://www.cpcgamereviews.com/ CPC Game Reviews]
* [http://computeremuzone.com/amstrad/ Amstrad Zone]
* [http://www.amstradcpc.info/ Amstrad CPC Info]


{{Amstrad}}
[[Category:Amstrad CPC|*Amstrad CPC]]
[[Category:Home computers]]


[[da:Amstrad]]
{{DEFAULTSORT:Amstrad Cpc}}
[[de:Amstrad CPC]]
[[Category:Amstrad CPC| ]]
[[Category:Computer-related introductions in 1984]]
[[fr:Amstrad CPC 464]]
[[it:Amstrad CPC]]
[[Category:Amstrad computers|CPC]]
[[Category:Z80-based home computers]]
[[pl:Amstrad CPC]]
[[Category:Computers designed in the United Kingdom]]
[[sv:Amstrad CPC]]

Latest revision as of 14:08, 9 January 2025

Amstrad CPC
DeveloperAmstrad
TypePersonal computer
GenerationThird
Release date1984; 41 years ago (1984)
Discontinued1990; 35 years ago (1990)
Units sold3 million
MediaCompact Cassette, 3-inch floppy disks
Operating systemAMSDOS with Locomotive BASIC 1.0 or 1.1; CP/M 2.2 or 3.0
CPUZilog Z80A @ 4 MHz
Memory64 or 128 KB,[1] expandable to 576 KB
Display160×200 pixels with 16 colours, 320×200 pixels with 4 colours, 640×200 pixels with 2 colours
GraphicsMotorola 6845 or compatible, custom gate array
SoundAY-3-8912, 3-voices, 8-octaves
InputKeyboard

The Amstrad CPC (short for "Colour Personal Computer") is a series of 8-bit home computers produced by Amstrad between 1984 and 1990. It was designed to compete in the mid-1980s home computer market dominated by the Commodore 64 and the ZX Spectrum; it successfully established itself primarily in the United Kingdom, France, Spain, and the German-speaking parts of Europe.

The series spawned a total of six distinct models: The CPC 464, CPC 664, and CPC 6128 were highly successful competitors in the European home computer market. The later 464 plus and 6128 plus, intended to prolong the system's lifecycle with hardware updates, were considerably less successful, as was the attempt to repackage the plus hardware into a game console as the GX4000.

The CPC models' hardware is based on the Zilog Z80A CPU, complemented with either 64 or 128 KB of RAM. Their computer-in-a-keyboard design prominently features an integrated storage device, either a compact cassette deck or 3-inch floppy disk drive. The main units were only sold bundled with either a colour, green-screen or monochrome monitor that doubles as the main unit's power supply.[2] Additionally, a wide range of first and third-party hardware extensions such as external disk drives, printers, and memory extensions, was available.

The CPC series was pitched against other home computers primarily used to play video games and enjoyed a strong supply of game software. The comparatively low price for a complete computer system with dedicated monitor, its high-resolution monochrome text and graphic capabilities and the possibility to run CP/M software also rendered the system attractive for business users, which was reflected by a wide selection of application software.

During its lifetime, the CPC series sold approximately three million units.[3]

The Schneider CPC 6128 was a Schneider-branded version of the Amstrad CPC 6128, and very similar in appearance.

Models

[edit]

The original range

[edit]

The philosophy behind the CPC series was twofold, firstly the concept was of an "all-in-one", where the computer, keyboard and its data storage device were combined in a single unit and sold with its own dedicated display monitor. Most home computers at that time such as ZX Spectrum series, Commodore 64, and BBC Micro relied on the use of the domestic television set and a separately connected tape recorder or disk drive. In itself, the all-in-one concept was not new, having been seen before on business-oriented machines and the Commodore PET.

Secondly, Amstrad founder Alan Sugar wanted the machine to resemble a "real computer, similar to what someone would see being used to check them in at the airport for their holidays",[4] and for the machine to not look like "a pregnant calculator"[5] – in reference presumably to the ZX81 and ZX Spectrum with their low cost, membrane-type keyboards.

Children playing Paperboy on the CPC 464 in 1988

CPC 464

[edit]

The CPC 464 was one of the most successful computers in Europe and sold more than two million units.[6]

The CPC 464 featured 64 KB RAM and an internal cassette deck. It was introduced in June 1984 in the UK. Initial suggested retail prices for the CPC 464 were £249.00/DM899.00 with a green screen and £359.00/DM1398.00 with a colour monitor. Following the introduction of the CPC 6128 in late 1985, suggested retail prices for the CPC 464 were cut by £50.00/DM100.00.

In 1990, the 464plus replaced the CPC 464 in the model line-up, and production of the CPC 464 was discontinued.

CPC 664

[edit]
A CPC 664 main unit (German Schneider-brand variant)

The CPC 664 features 64 KB RAM and an internal 3-inch floppy disk drive. It was introduced on 25 April 1985 in the UK.[7] Initial suggested retail prices for the CPC 664 were £339.00/DM1198.00 with a green screen and £449.00/DM1998.00 with a colour monitor.

After the successful release of the CPC 464, consumers were constantly asking for two improvements: more memory and an internal disk drive. For Amstrad, the latter was easier to realise. At the deliberately low-key introduction of the CPC 664, the machine was positioned not only as the lowest-cost disk system but even the lowest-cost CP/M 2.2 machine. In the Amstrad CPC product range the CPC 664 complemented the CPC 464 which was neither discontinued nor reduced in price.[8]

Compared to the CPC 464, the CPC 664's main unit has been significantly redesigned, not only to accommodate the floppy disk drive but also with a redesigned keyboard area. Touted as "ergonomic" by Amstrad's promotional material, the keyboard is noticeably tilted to the front with MSX-style cursor keys above the numeric keypad. Compared to the CPC 464's multicoloured keyboard, the CPC 664's keys are kept in a much quieter grey and pale blue colour scheme.

The back of the CPC 664 main unit features the same connectors as the CPC 464, with the exception of an additional 12V power lead. Unlike the CPC 464's cassette tape drive that could be powered off the main unit's 5V voltage, the CPC 664's floppy disk drive requires an additional 12V voltage. This voltage had to be separately supplied by an updated version of the bundled green screen/colour monitor (GT-65 and CTM-644 respectively).

The CPC 664 was only produced for approximately six months. In late 1985, when the CPC 6128 was introduced in Europe, Amstrad decided not to keep three models in the line-up, and production of the CPC 664 was discontinued.[9]

CPC 6128

[edit]
CPC 6128 main circuit board.

The CPC 6128 features 128 KB RAM and an internal 3-inch floppy disk drive. Aside from various hardware and firmware improvements, one of the CPC 6128's most prominent features is the compatibility with the CP/M+ operating system that rendered it attractive for business uses.

The CPC 6128 was released on 13 June 1985 and initially only sold in the US.[7] Imported and distributed by Indescomp, Inc. of Chicago, it was the first Amstrad product to be sold in the United States, a market that at the time was traditionally hostile towards European computer manufacturers.[10] Two months later, on 15 August 1985, it arrived in Europe[7] and replaced the CPC 664 in the CPC model line-up. Initial suggested retail prices for the CPC 6128 were US$699.00/£299.00/DM1598.00 with a green screen and US$799.00/£399.00/DM2098.00 with a colour monitor.

In 1990, the 6128plus replaced the CPC 6128 in the model line-up, and production of the CPC 6128 was discontinued.

The plus range

[edit]

In 1990, confronted with a changing home computer market, Amstrad decided to refresh the CPC model range by introducing a new range variantly labelled plus or PLUS, 1990, or CPC+ range. The main goals were numerous enhancements to the existing CPC hardware platform, to restyle the casework to provide a contemporary appearance, and to add native support of cartridge media. The new model palette includes three variants, the 464plus and 6128plus computers and the GX4000 video game console. The "CPC" abbreviation was dropped from the model names.

The redesign significantly enhanced the CPC hardware, mainly to rectify its previous shortcomings as a gaming platform. The redesigned video hardware allows for 16 hardware sprites[11] and soft scrolling, with a colour palette extended from a maximum of 16 colours (plus separately definable border) at one time from a choice of 27, increased to a maximum of 31 (16 for background and 15 for hardware sprites) out of 4096. The enhanced sound hardware offers automatic DMA transfer, allowing more complex sound effects with a significantly reduced processor overhead. Other hardware enhancements include the support of analogue joysticks, 8-bit printers, and ROM cartridges up to 4 Mbits.

The new range of models was intended to be completely backwards compatible with the original CPC models. Its enhanced features are only available after a deliberately obscure unlocking mechanism has been triggered, thus preventing existing CPC software from accidentally invoking them.[12]

Despite the significant hardware enhancements, many viewed it as outdated, being based on an 8-bit CPU, and it failed to attract both customers and software producers who were moving towards systems such as the Amiga and Mega Drive which was launched a few short months after the plus range. The plus range was a commercial failure,[13] and production was discontinued shortly after its introduction in 1990.

464 plus, 6128 plus

[edit]
A 6128 plus main unit (with Spanish keyboard layout)

The 464 plus and 6128 plus models were intended as "more sophisticated and stylish" replacements of the CPC 464 and CPC 6128. Based on the redesigned plus hardware platform, they share the same base characteristics as their predecessors: The 464 plus is equipped with 64 KB RAM and a cassette tape drive, the 6128 plus features 128 KB RAM and a 3" floppy disk drive. Both models share a common case layout with a keyboard taken over from the CPC 6128 model, and the respective mass storage drive inserted in a case breakout.

In order to simplify the EMC screening process, the edge connectors of the previous models have been replaced with micro-ribbon connectors as previously used on the German Schneider CPC 6128. As a result, a wide range of extensions for the original CPC range are connector-incompatible with the 464 plus and 6128 plus. In addition, the 6128plus does not have a tape socket for an external tape drive.

The plus range is not equipped with an on-board ROM, and thus the 464 plus and the 6128 plus do not contain a firmware. Instead, Amstrad provided the firmware for both models via the ROM extension facility, contained on the included Burnin' Rubber and Locomotive BASIC cartridge. This resulted in reduced hardware localization cost (only some select key caps and case labels had to be localized) with the added benefit of a rudimentary copy protection mechanism (without a firmware present, the machine itself could not copy a game cartridge's content).[12] As the enhanced V4 firmware's structural differences causes problems with some CPC software directly calling firmware functions by their memory addresses, Amstrad separately sold a cartridge containing the original CPC 6128's V3 firmware.[14]

Both the 464 plus and the 6128 plus were introduced to the public in September 1990. Initial suggested retail prices were £229/1,990 F with a monochrome monitor and £329/2,990 F with a colour monitor for the 464 plus, and £329/2,990 F with a monochrome monitor and £429/3,990 F with a colour monitor for the 6128plus.[15]

GX4000

[edit]
The Amstrad GX4000

Developed as part of the plus range, the GX4000 was Amstrad's short-lived attempt to enter the video game consoles market. Sharing the plus range's enhanced hardware characteristics, it represents the bare minimum variant of the range without a keyboard or support for mass storage devices.[12] It came bundled with 2 paddle controllers and the racing game Burnin' Rubber.

Special models and clones

[edit]

CPC 472

[edit]
CPC 472

During the August holidays of 1985, Spain briefly introduced an import tax of 15 000 pesetas (€90.15) on computers containing 64 KB or less of RAM (Royal Decree 1215/1985[16] and 1558/1985[17]), and a new law (Royal Decree 1250/1985[18]) mandated that all computers sold in Spain must have a Spanish keyboard. To circumvent this, Amstrad's Spanish distributor Indescomp (later to become Amstrad Spain) created and distributed the CPC 472, a modified version of the CPC 464. Its main differences are a small additional daughter board containing a CPC 664 ROM chip and an 8 KB memory chip, and a keyboard with a ñ key (although some of them were temporarily manufactured without the ñ key). The sole purpose of the 8 KB memory chip (which is not electrically connected to the machine, so consequently rendered unusable) is to increase the machine's total memory specs to 72 KB in order to circumvent the import tax. Some months later, Spain joined the European Communities by the Treaty of Accession 1985 and the import tax was suppressed, so Amstrad added the ñ key for the 464 and production of the CPC 472 was discontinued.[19][better source needed]

KC compact

[edit]
The Kleincomputer KC compact

The KC compact [de] ("Kleincomputer" - which means "small computer" - being a rather literal German translation of the English "microcomputer") is a clone of the Amstrad CPC built by East Germany's VEB Mikroelektronik Mühlhausen, part of VEB Kombinat Mikroelektronik Erfurt, in October 1989. Although the machine included various substitutes and emulations of an Amstrad CPC's hardware, the machine is largely compatible with Amstrad CPC software. It is equipped with 64 KB of memory and a CPC 6128's firmware customized to the modified hardware, including a copy of Locomotive BASIC 1.1 modified in the startup banner only. The expansion port is a K 1520 bus slot. The KC compact is the last 8-bit computer introduced in East Germany.[20] Due to the German reunification happening at the time of the release, only a very small number of systems were sold. The KC compact can be emulated by free software JKCEMU.[21]

Aleste 520EX

[edit]

In 1993, Omsk, Russia based company Patisonic released the Aleste 520EX, a computer highly compatible with the Amstrad CPC 6128.[22][23][24] It could also be switched into an MSX mode. An expansion board named Magic Sound allowed to play Scream Tracker files.

Reception

[edit]

Your Computer concluded that the CPC 464 had "Superior graphics and sound, an excellent Basic coupled with a flexible operating system" and that Amstrad's target sales of 200,000 by the end of 1984 were realistic.[25]

A BYTE columnist in January 1985 called the CPC 464 "the closest yet to filling" his criteria for a useful home computer, including good keyboard, 80-column text, inexpensive disk drive, and support for a mainstream operating system like CP/M.[26]

Hardware

[edit]

Processor

[edit]

The entire CPC series is based on the Zilog Z80; a processor, clocked at 4 MHz.[27]

In order to avoid the CPU and the video logic simultaneously accessing the shared main memory and causing video corruption ("snowing"), CPU memory access is constrained to occur on microsecond boundaries. This effectively pads every machine cycle to four clock cycles, causing a minor loss of processing power and resulting in what Amstrad estimated to be an "effective clock rate" of "approximately 3.3 MHz".[28]

Memory

[edit]

Amstrad CPCs are equipped with either 64 (CPC 464, CPC 664, 464plus, GX4000) or 128 (CPC 6128, 6128plus) KB of RAM.[27][29] This base memory can be extended by up to 512 KB using memory expansions sold by third-party manufacturers, and by up to 4096 KB using experimental methods developed by hardware enthusiasts. Because the Z80 processor is only able to directly address 64 KB of memory, additional memory from the 128 KB models and memory expansions is made available using bank switching.

Video

[edit]
Mode 1 image on a GT65 green monitor

Underlying a CPC's video output is the unusual pairing of a CRTC (Motorola 6845 or compatible) with a custom-designed gate array to generate a pixel display output. CPC 6128s later in production as well as the models from the plus range integrate both the CRTC and the gate array's functions with the system's ASIC.

Three built-in display resolutions are available: 160×200 pixels with 16 colours ("Mode 0", 20 text columns), 320×200 pixels with 4 colours ("Mode 1", 40 text columns), and 640×200 pixels with 2 colours ("Mode 2", 80 text columns).[27] Increased screen size can be achieved by reprogramming the CRTC.

The original CPC video hardware supports a colour palette of 27 colours,[27] generated from RGB colour space with each colour component assigned as either off, half on, or on (3 level RGB palette). The plus range extended the palette to 4096 colours, also generated from RGB with 4 bits each for red, green and blue (12-bit RGB).[12]

Amstrad MP1 external television adapter

With the exception of the GX4000, all CPC models lack an RF television or composite video output and instead shipped with a 6-pin RGB DIN connector, also used by Acorn computers, to connect the supplied Amstrad monitor.[27] This connector delivers a 1v p-p analogue RGB with a 50 Hz composite sync signal that, if wired correctly, can drive a 50 Hz SCART television. External adapters for RF television were available as a first-party hardware accessory.

Audio

[edit]

The CPC uses the General Instrument AY-3-8912 sound chip,[27] providing three channels, each configurable to generate square waves, white noise or both. A small array of hardware volume envelopes are available.

Output is provided in mono by a small (4 cm) built-in loudspeaker with volume control, driven by an internal amplifier. Stereo output is provided through a 3.5 mm headphones jack.

It is possible to play back digital sound samples at a resolution of approximately 5-bit by sending a stream of values to the sound chip. This technique is very processor-intensive and hard to combine with any other processing. Examples are the title screens or other non-playable scenes of games like Chase H.Q., Meltdown, and RoboCop. The later Plus models incorporated a DMA engine in order to offload this processing.

Floppy disk drive

[edit]
Built-in disk drive of the CPC 6128
A CPC 6128 loading Turbo Esprit from its internal floppy drive
3-inch floppy disks used on CPC machines

Amstrad uses Matsushita's 3" floppy disk drive [ref: CPCWiki], which was compatible with Hitachi's existing 3" floppy disk format.[26] The chosen drive (built-in for later models) is a single-sided 40-track unit that requires the user to remove and flip the disk to access the other side.[29] Each side has its own independent write-protect switch.[29] The sides are termed "A" and "B", with each one commonly formatted to 180 KB (in AMSDOS format, comprising 2 KB directory and 178 KB storage) for a total of 360 KB per disk.

The interface with the drives is an NEC 765 FDC, used for the same purpose in the IBM PC/XT, PC/AT and PS/2 machines. Its features are not fully used in order to cut costs, namely DMA transfers and support for single density disks; they were formatted as double density using modified frequency modulation.

Discs were shipped in a paper sleeve or a hard plastic case resembling a compact disc "jewel" case. The casing is thicker and more rigid than that of 3.5 inch diskettes, and designed to be mailed without any additional packaging[citation needed]. A sliding metal cover to protect the media surface is internal to the casing and latched, unlike the simple external sliding cover of Sony's version. They were significantly more expensive than both 5.25 inch and 3.5 inch alternatives. This, combined with their low nominal capacities and their essentially proprietary nature, led to the format being discontinued shortly after the CPC itself was discontinued.

Apart from Amstrad's other 3-inch machines (the PCW and the ZX Spectrum +3), the few other computer systems to use them included the Sega SF-7000 and CP/M systems such as the Tatung Einstein and Osborne machines. They also found use on embedded systems.

The Shugart-standard interface means that Amstrad CPC machines are able to use standard 3", 3½" or 5¼" drives as their second drive. Programs such as ROMDOS and ParaDOS extend the standard AMSDOS system to provide support for double-sided, 80-track formats, enabling up to 800 KB to be stored on a single disk.

The 3-inch disks themselves are usually known as "discs" on the CPC, following the spelling on the machine's plastic casing and conventional British English spelling.

Expansion

[edit]
Back of the case of a CPC 464, with the mini-jack, joystick and printer ports.

The hardware and firmware was designed to be able to access software provided on external ROMs. Each ROM has to be a 16 KB block and is switched in and out of the memory space shared with the video RAM. The Amstrad firmware is deliberately designed so that new software could be easily accessed from these ROMs. Popular applications were marketed on ROM, particularly word processing and programming utility software (examples are Protext and Brunword of the former, and the MAXAM assembler of the latter type).

Such extra ROM chips do not plug directly into the CPC itself, but into extra plug-in "rom boxes" which contain sockets for the ROM chips and a minimal amount of decoding circuitry for the main machine to be able to switch between them. These boxes were either marketed commercially or could be built by competent hobbyists and they attached to the main expansion port at the back of the machine. Software on ROM loads much faster than from disc or tape and the machine's boot-up sequence was designed to evaluate ROMs it found and optionally hand over control of the machine to them. This allows significant customisation of the functionality of the machine, something that enthusiasts exploited for various purposes.[30] However, the typical users would probably not be aware of this added ROM functionality unless they read the CPC press, as it is not described in the user manual and was hardly ever mentioned in marketing literature. It is, however, documented in the official Amstrad firmware manual.

The machines also feature a 9-pin Atari joystick port that will either directly take one joystick, or two joysticks by use of a splitter cable.[27]

Peripherals

[edit]

RS232 serial adapters

[edit]

Amstrad issued two RS-232-C D25 serial interfaces, attached to the expansion connector on the rear of the machine, with a through-connector for the CPC 464 disk drive or other peripherals.

The original interface came with a Book of Spells for facilitating data transfer between other systems using a proprietary protocol in the device's own ROM, as well as terminal software to connect to British Telecom's Prestel service. A separate version of the ROM was created for the U.S. market due to the use of the commands "|SUCK" and "|BLOW", which were considered unacceptable there.

Software and hardware limitations in this interface led to its replacement with an Amstrad-branded version of a compatible alternative by Pace. Serial interfaces were also available from third-party vendors such as KDS Electronics and Cirkit.

Software

[edit]

BASIC and operating system

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Locomotive BASIC on the Amstrad CPC 464

Like most home computers at the time, the CPC has its OS and a BASIC interpreter built in as ROM. It uses Locomotive BASIC - an improved version of Locomotive Software's Z80 BASIC for the BBC Micro co-processor board. It is particularly notable for providing easy access to the machine's video and audio resources in contrast to the POKE commands required on generic Microsoft implementations. Other unusual features include timed event handling with the AFTER and EVERY commands, and text-based windowing.

CP/M

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Digital Research's CP/M operating system was supplied with the 664 and 6128 disk-based systems, and the DDI-1 disk expansion unit for the 464. 64k machines shipped with CP/M 2.2 alone, while the 128k machines also include CP/M 3.1. The compact CP/M 2.2 implementation is largely stored on the boot sectors of a 3" disk in what was called "System format"; typing |CPM from Locomotive BASIC would load code from these sectors, making it a popular choice for custom game loading routines. The CP/M 3.1 implementation is largely in a separate file which is in turn loaded from the boot sector. Much public domain CP/M software was made available for the CPC, from word-processors such as VDE to complete bulletin board systems such as ROS.

Other languages

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Although it was possible to obtain compilers for Locomotive BASIC, C and Pascal, the majority of the CPC's software was written in native Z80 assembly language. Popular assemblers were Hisoft's Devpac, Arnor's Maxam, and (in France) DAMS. Disk-based CPC (not Plus) systems shipped with an interpreter for the educational language LOGO, booted from CP/M 2.2 but largely CPC-specific with much code resident in the AMSDOS ROM; 6128 machines also include a CP/M 3.1, non-ROM version. A C compiler was also written and made available for the European market through Tandy Europe, by Micro Business products.

Roland

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In an attempt to give the CPC a recognisable mascot, a number of games by Amstrad's in-house software publisher Amsoft have been tagged with the Roland name. However, as the games had not been designed around the Roland character and only had the branding added later, the character design varies immensely, from a spiky-haired blonde teenager (Roland Goes Digging) to a white cube with legs (Roland Goes Square Bashing) or a mutant flea (Roland in the Caves). The only two games with similar gameplay and main character design are Roland in Time and its sequel Roland in Space. The Roland character was named after Roland Perry, one of the lead designers of the original CPC range.

Schneider Computer Division

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Schneider Computer Division logo
Schneider CPC 6128 with visible micro ribbon connectors at the top (back) side
Schneider CPC Demo Tape Presentation Compact Cassette came with the CPC 464

In order to market its computers in Germany, Austria, and Switzerland where Amstrad did not have any distribution structures, Amstrad entered a partnership with Schneider Rundfunkwerke AG, a German company that - very much like Amstrad itself - was previously only known for value-priced audio products. In 1984, Schneider's Schneider Computer Division daughter company was created specifically for the task, and the complete Amstrad CPC line-up was branded and sold as Schneider CPC.

Although they are based on the same hardware, the Schneider CPC models differ from the Amstrad CPC models in several details. Most prominently, the Schneider CPC 464 and CPC 664 keyboards featured grey instead of coloured keys, but still in the original British keyboard layout. To achieve a German "QWERTZ" keyboard layout, Schneider marketed a small software program to reassign the keys as well as sticker labels for the keys.[31] In order to conform with stricter German EMC regulations, the complete Schneider CPC line-up is equipped with an internal metal shielding. For the same reason, the Schneider CPC 6128 features micro ribbon type connectors instead of edge connectors. Both the greyscale keyboard and the micro ribbon connectors found their way up into the design of later Amstrad CPC models.

In 1988, after Schneider refused to market Amstrad's AT-compatible computer line, the cooperation ended. Schneider went on to sell the remaining stock of Schneider CPC models and used their now well-established market position to introduce its own PC designs. With the formation of its German daughter company Amstrad GmbH to distribute its product lines including the CPC 464 and CPC 6128, Amstrad attempted but ultimately failed to establish their own brand in the German-speaking parts of Europe.[32][33]

Community

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The Amstrad CPC enjoyed a strong and long lifetime, mainly due to the machines use for businesses as well as gaming. Dedicated programmers continued working on the CPC range, even producing graphical user interface (GUI) operating systems such as SymbOS. Internet sites devoted to the CPC have appeared from around the world featuring forums, news, hardware, software, programming and games. CPC Magazines appeared during the 1980s including publications in countries such as Britain, France, Spain, Germany, Denmark, Australia, and Greece. Titles included the official Amstrad Computer User publication,[34] as well as independent titles like Amstrad Action,[34] Amtix!,[34] Computing with the Amstrad CPC,[34] CPC Attack,[34] Australia's The Amstrad User, France's Amstrad Cent Pour Cent and Amstar. Following the CPC's end of production, Amstrad gave permission for the CPC ROMs to be distributed freely as long as the copyright message is not changed and that it is acknowledged that Amstrad still holds copyright, giving emulator authors the possibility to ship the CPC firmware with their programs.[35]

Influence on other Amstrad machines

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Amstrad followed their success with the CPC 464 by launching the Amstrad PCW word-processor range, another Z80-based machine with a 3" disk drive and software by Locomotive Software. The PCW was originally developed to be partly compatible with an improved version of the CPC (ANT, or Arnold Number Two - the CPC's development codename was Arnold).[36][37] However, Amstrad decided to focus on the PCW, and the ANT project never came to market.

On 7 April 1986, Amstrad announced it had bought from Sinclair Research "...the worldwide rights to sell and manufacture all existing and future Sinclair computers and computer products, together with the Sinclair brand name and those intellectual property rights where they relate to computers and computer-related products."[38] which included the ZX Spectrum, for £5 million. This included Sinclair's unsold stock of Sinclair QLs and Spectrums. Amstrad made more than £5 million on selling these surplus machines alone. Amstrad launched two new variants of the Spectrum: the ZX Spectrum +2, based on the ZX Spectrum 128, with a built-in tape drive (like the CPC 464) and, the following year, the ZX Spectrum +3, with a built-in floppy disk drive (similar to the CPC 664 and 6128), taking the 3" discs that Amstrad CPC machines used.

Production Timeline

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See also

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Notes and references

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  1. ^ Transistorized memory, such as RAM, ROM, flash and cache sizes as well as file sizes are specified using binary meanings for K (10241), M (10242), G (10243), etc.
  2. ^ CPC464 User Manual, p. 11, Amstrad Consumer Electronics Plc.
  3. ^ "Amstrad Product Archive". Archived from the original on 9 May 2008. Retrieved 25 September 2009.
  4. ^ Chas Newkey-Burden (2010). Sir Alan Sugar: The Biography. John Blake. ISBN 978-1-84454-891-0.
  5. ^ Alan Sugar (2010). What You See Is What You Get: My Autobiography. Pan Macmillan. ISBN 978-0-230-74933-7.
  6. ^ "OLD-COMPUTERS.COM : The Museum". www.old-computers.com. Archived from the original on 25 March 2019. Retrieved 27 June 2016.
  7. ^ a b c "Special Feature: Happy Birthday!". Popular Computing Weekly. 1 May 1987. pp. 14–18 (18).
  8. ^ The CPC664, Amstrad Computer User May 1985, P. 42-46.
  9. ^ "Interview de M. Roland Perry" (in French). Amstrad Forever. Archived from the original on 20 July 2011. Retrieved 2 April 2010.
  10. ^ Amstrad Computer User, "User News...", August 1985, p. 7.
  11. ^ "Original Arnold V Specs". CPCWiki. Retrieved 8 January 2025.
  12. ^ a b c d Lawson, Cliff. "Arnold "V" Specification 1.4". Amstrad. Archived from the original on 18 November 2000.
  13. ^ Retro Gamer issue 83, From the Archives: Radical Software
  14. ^ "Amstrad System Cartridges". grimware.org. Archived from the original on 1 February 2010. Retrieved 22 March 2010.
  15. ^ Paris in the Spring, Amstrad Action Issue 60, September 1990, P. 34-36
  16. ^ "BOE.es - BOE-A-1985-15514 Real Decreto 1215/1985, de 17 de julio, por el que se modifican determinadas subpartidas del arancel de Aduanas". www.boe.es (in Spanish).
  17. ^ "BOE.es - BOE-A-1985-18847 Real Decreto 1558/1985, de 28 de agosto, por el que se aclara el alcance del mínimo específico introducido en la subpartida 84.53.B.II del Arancel de Aduanas, por el Real Decreto 1215/1985". www.boe.es (in Spanish).
  18. ^ "BOE.es - BOE-A-1985-15611 Real Decreto 1250/1985, de 19 de junio, por el que se establece la sujeción a especificaciones técnicas de los terminales de pantalla con teclado, periféricos para entrada y representación de información en equipo de proceso de datos". www.boe.es (in Spanish).
  19. ^ "CPC472". CPCWiki. Retrieved 17 August 2011.
  20. ^ "KC Compact Documentation". Archived from the original on 20 February 2022. Retrieved 11 February 2023.
  21. ^ "JKCEMU - Kleincomputer-Emulator (in German)". www.jens-mueller.org. Retrieved 6 March 2023.
  22. ^ "Aleste 520EX - CPCWiki". www.cpcwiki.eu.
  23. ^ "Aleste 520EX". aleste520.narod.ru.
  24. ^ "Spanish page". Archived from the original on 13 March 2016. Retrieved 10 January 2015.
  25. ^ Beeesley, Simon (June 1986). "Review: Amstrad". Your Computer. Vol. 4, no. 6. Sutton, Surrey: Business Press International Ltd. pp. 70–72. Retrieved 8 January 2025.
  26. ^ a b Pountain, Dick (January 1985). "The Amstrad CPC 464". BYTE. Vol. 10, no. 1. pp. 401–407. Retrieved 9 January 2015.
  27. ^ a b c d e f g Technical Specification, CPC464 Service Manual, p. 2., Amstrad Consumer Electronics Plc.
  28. ^ CPC464/664/6128 Firmware (Soft 968), Section 1
  29. ^ a b c Technical Specification, CPC6128 Service Manual, p. 31., Amstrad Consumer Electronics Plc.
  30. ^ "ROM :: Amstrad CPC -- 8bit Projects For Everyone". 8bit.yarek.pl. Archived from the original on 8 August 2009. Retrieved 1 November 2009.
  31. ^ CPC Schneider International 6/85, P. 7
  32. ^ CeBIT '88, Schneider Magazin 5/88, P. 6-8
  33. ^ "Defunct Audio Manufacturers". Retrieved 20 September 2009.
  34. ^ a b c d e "CPC UK Magazines". Nicholas Campbell. Archived from the original on 31 October 2001. Retrieved 6 May 2008.
  35. ^ Lawson, Cliff. "Lawson emulation". Cliff Lawson. Archived from the original on 10 May 2008. Retrieved 6 May 2008.
  36. ^ Smith, Tony (12 February 2014). "You're NOT fired: The story of Amstrad's amazing CPC 464". www.theregister.co.uk. Retrieved 20 December 2018.
  37. ^ "The CPC that never was". Retro Gamer. 28 December 2017.
  38. ^ "CRASH 28 - News". www.crashonline.org.uk.
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