View source for Amstrad CPC

{{short description|Home computers produced by Amstrad}}
{{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      = Amstrad CPC 464 with colour monitor
| 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&nbsp;[[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    = {{GBP|359|1984|round=-1}} with colour monitor
| sound        = [[AY-3-8912]], 3-voices, 8-octaves
}}

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, and also Canada.

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 ''[[Amstrad GX4000|GX4000]]''.

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 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.<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>
[[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 -->

==Models==
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.

[[File:Cpc464.computer.750pix.jpg|thumb|Children playing ''[[Paperboy (video game)|Paperboy]]'' on the CPC 464 in 1988]]

=== CPC 464 ===
{{Main|Amstrad CPC 464}}
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.

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

=== CPC 664 ===
[[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.

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>

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.<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>

=== CPC 6128 ===
[[File:Amstrad CPC6128, keyboard removed.jpg|thumb|CPC 6128 main circuit board.]]
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.

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

===The ''plus range''===
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 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>

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.

====464 plus, 6128 plus====
[[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 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>

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>

====GX4000====
[[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''.

===Special models and clones===

====CPC 472====
[[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 |pages=23677 |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 |pages=27743–27744 |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 |pages=23840–23841 |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====
<!-- 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====
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}}

==Reception==

''[[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>

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>

==Hardware==

===Processor===
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 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>

===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]].

===Video===
[[File:Schneider CPC6128 with green monitor GT65, Wikipedia logo.jpg|thumb|Mode 1 image on a GT65 green monitor]]
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.

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"/>

[[File:Amstrad MP-1.jpg|thumb|Amstrad MP1 external television adapter]]
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===
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.

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 [[Direct memory access|DMA]] engine in order to offload this processing.

===Floppy disk drive===
[[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]].

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.

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 [[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.

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===
[[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.

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"/>

==Peripherals==

===RS232 serial adapters===
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.

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.

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.

==Software==

===BASIC and operating system===
[[File:Amstrad CPC screen closeup.jpg|thumb|right|Locomotive BASIC on the Amstrad CPC 464]]
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===
[[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 instruction set|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==
* [[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]]
* [[GX4000]]
* [[SymbOS]] (multitasking operating system)

==Notes and references==
{{Reflist}}

==External links==
{{Commons}}
* [http://www.cpcwiki.eu/ CPC-Wiki] (CPC specific Wiki containing further information)
* [http://CPC-Power.com CPC-Power]
* [http://www.cpctech.org.uk/ Unofficial Amstrad WWW Resource]
* [http://www.futureos.de/ New OS for the CPC]

{{Amstrad}}

{{DEFAULTSORT:Amstrad Cpc}}
[[Category:Amstrad CPC| ]]
[[Category:Computer-related introductions in 1984]]
[[Category:Amstrad computers|CPC]]
[[Category:Z80-based home computers]]
[[Category:Computers designed in the United Kingdom]]