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The Amstrad CPC (short for "Colour Personal Computer") is a series of
8-bit In computer architecture, 8-bit integers or other data units are those that are 8 bits wide (1 octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data bu ...
home computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a s ...
s produced by
Amstrad Amstrad plc was a British consumer electronics company, founded in 1968 by Alan Sugar. During the 1980s, the company was known for its Home computer, home computers beginning with the Amstrad CPC and later also the ZX Spectrum range after the ...
between 1984 and 1990. It was designed to compete in the mid-1980s home computer market dominated by the
Commodore 64 The Commodore 64, also known as the C64, is an 8-bit computing, 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in ...
and the
ZX Spectrum The ZX Spectrum () is an 8-bit computing, 8-bit home computer developed and marketed by Sinclair Research. One of the most influential computers ever made and one of the all-time bestselling British computers, over five million units were sold. ...
; 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 '' 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 A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, log ...
, complemented with either 64 or 128 KB of
RAM Ram, ram, or RAM most commonly refers to: * A male sheep * Random-access memory, computer memory * Ram Trucks, US, since 2009 ** List of vehicles named Dodge Ram, trucks and vans ** Ram Pickup, produced by Ram Trucks Ram, ram, or RAM may also ref ...
. 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.CPC464 User Manual, p. 11, Amstrad Consumer Electronics Plc. 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 CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/Intel 8085, 85-based microcomputers by Gary Kildall of Digital Research, Dig ...
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.


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 The ZX Spectrum () is an 8-bit computing, 8-bit home computer developed and marketed by Sinclair Research. One of the most influential computers ever made and one of the all-time bestselling British computers, over five million units were sold. ...
series,
Commodore 64 The Commodore 64, also known as the C64, is an 8-bit computing, 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in ...
, and
BBC Micro The BBC Microcomputer System, or BBC Micro, is a family of microcomputers developed and manufactured by Acorn Computers in the early 1980s as part of the BBC's Computer Literacy Project. Launched in December 1981, it was showcased across severa ...
relied on the use of the domestic
television Television (TV) is a telecommunication medium for transmitting moving images and sound. Additionally, the term can refer to a physical television set rather than the medium of transmission. Television is a mass medium for advertising, ...
set and a separately connected
tape recorder An audio tape recorder, also known as a tape deck, tape player or tape machine or simply a tape recorder, is a sound recording and reproduction device that records and plays back sounds usually using magnetic tape for storage. In its present ...
or
disk drive Disc or disk may refer to: * Disk (mathematics), a two dimensional shape, the interior of a circle * Disk storage * Optical disc * Floppy disk Music * Disc (band), an American experimental music band * ''Disk'' (album), a 1995 EP by Moby Other ...
. In itself, the all-in-one concept was not new, having been seen before on business-oriented machines and the
Commodore PET The Commodore PET is a line of personal computers produced starting in 1977 by Commodore International. A single all-in-one case combines a MOS Technology 6502 microprocessor, Commodore BASIC in read-only memory, keyboard, monochrome monitor ...
. Secondly, Amstrad founder
Alan Sugar Alan Michael Sugar, Baron Sugar (born 24 March 1947) is a British business magnate, media personality, author, politician, and political adviser. Sugar began what would later become his largest business venture, consumer electronics company A ...
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", and for the machine to not look like "a pregnant calculator" – in reference presumably to the
ZX81 The ZX81 is a home computer that was produced by Sinclair Research and manufactured in Dundee, Scotland, by Timex Corporation. It was launched in the United Kingdom in March 1981 as the successor to Sinclair's ZX80 and designed to be a low-c ...
and
ZX Spectrum The ZX Spectrum () is an 8-bit computing, 8-bit home computer developed and marketed by Sinclair Research. One of the most influential computers ever made and one of the all-time bestselling British computers, over five million units were sold. ...
with their low cost, membrane-type keyboards.


CPC 464

The CPC 464 was one of the most successful computers in Europe and sold more than two million units. The CPC 464 featured 64 KB RAM and an internal
cassette deck A cassette deck is a type of tape machine for playing and recording audio cassettes that does not have a built-in power amplifier or speakers, and serves primarily as a Transport (recording), transport. It can be a part of an automotive entertai ...
. 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

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. 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. 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 MSX is a standardized home computer architecture, announced by ASCII Corporation on June 16, 1983. It was initially conceived by Microsoft as a product for the Eastern sector, and jointly marketed by Kazuhiko Nishi, the director at ASCII Corpo ...
-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.


CPC 6128

The CPC 6128 features 128 KB RAM and an internal 3-inch floppy disk drive. Aside from various hardware and
firmware In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, h ...
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. 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. Two months later, on 15 August 1985, it arrived in Europe 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 hardware sprites 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 A ROM cartridge, usually referred to in context simply as a cartridge, cart, cassette, or card, is a replaceable part designed to be connected to a consumer electronics device such as a home computer, video game console or, to a lesser extent, ...
s up to 4 Mbits. The new range of models was intended to be completely
backwards compatible In telecommunications and computing, backward compatibility (or backwards compatibility) is a property of an operating system, software, real-world product, or technology that allows for interoperability with an older legacy system, or with inpu ...
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. 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 Amiga is a family of personal computers produced by Commodore International, Commodore from 1985 until the company's bankruptcy in 1994, with production by others afterward. The original model is one of a number of mid-1980s computers with 16-b ...
and
Mega Drive The Sega Genesis, known as the outside North America, is a 16-bit Fourth generation of video game consoles, fourth generation home video game console developed and sold by Sega. It was Sega's third console and the successor to the Master Sys ...
which was launched a few short months after the plus range. The plus range was a commercial failure, and production was discontinued shortly after its introduction in 1990.


464 plus, 6128 plus

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 Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * ...
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 Copy protection, also known as content protection, copy prevention and copy restriction, is any measure to enforce copyright by preventing the reproduction of software, films, music, and other media. Copy protection is most commonly found on vid ...
mechanism (without a firmware present, the machine itself could not copy a game cartridge's content). 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. Both the 464 plus and the 6128 plus were introduced to the public in September 1990. Initial suggested retail prices were / with a monochrome monitor and / with a colour monitor for the 464 plus, and / with a monochrome monitor and / with a colour monitor for the 6128plus.


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. It came bundled with 2
paddle controller A paddle is a game controller with a round ''wheel'' and one or more ''fire buttons'', where the wheel is typically used to control movement of the player object along one axis of the video screen. A paddle controller rotates through a fixed arc ...
s and the racing game ''Burnin' Rubber''.


Special models and clones


CPC 472

During the August holidays of 1985, Spain briefly introduced an import tax of 15 000 pesetas () on computers containing 64 KB or less of RAM (Royal Decree 1215/1985 and 1558/1985), and a new law (Royal Decree 1250/1985) 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 The European Communities (EC) were three international organizations that were governed by the same set of Institutions of the European Union, institutions. These were the European Coal and Steel Community (ECSC), the European Atomic Energy Co ...
by the
Treaty of Accession 1985 The Treaty of Accession 1985 was the agreement between the member states of the European Communities, Spain and Portugal, concerning these countries' accession into the EC. It entered into force on 1 January 1986. The Treaty arranged accession ...
and the import tax was suppressed, so Amstrad added the ñ key for the 464 and production of the CPC 472 was discontinued.


KC compact

The ' ("" - 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 East Germany, officially known as the German Democratic Republic (GDR), was a country in Central Europe from Foundation of East Germany, its formation on 7 October 1949 until German reunification, its reunification with West Germany (FRG) on ...
's ', part of ', 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. Due to the
German reunification German reunification () was the process of re-establishing Germany as a single sovereign state, which began on 9 November 1989 and culminated on 3 October 1990 with the dissolution of the East Germany, German Democratic Republic and the int ...
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''.


Aleste 520EX

In 1993, Omsk, Russia based company Patisonic released the Aleste 520EX, a computer highly compatible with the Amstrad CPC 6128. It could also be switched into an
MSX MSX is a standardized home computer architecture, announced by ASCII Corporation on June 16, 1983. It was initially conceived by Microsoft as a product for the Eastern sector, and jointly marketed by Kazuhiko Nishi, the director at ASCII Corpo ...
mode. An expansion board named ''Magic Sound'' allowed to play
Scream Tracker ''Scream Tracker'' is a tracker (an integrated multi-track step sequencer and sampler as a software application). It was created by Psi (Sami Tammilehto), one of the founders of the Finnish demogroup Future Crew. It was written in C and assem ...
files.


Reception

'' 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. A ''
BYTE The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable un ...
'' 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.


Hardware


Processor

The entire CPC series is based on the
Zilog Z80 The Zilog Z80 is an 8-bit computing, 8-bit microprocessor designed by Zilog that played an important role in the evolution of early personal computing. Launched in 1976, it was designed to be Backward compatibility, software-compatible with the ...
; a processor, clocked at 4 
MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base u ...
.Technical Specification, CPC464 Service Manual, p. 2., Amstrad Consumer Electronics Plc. 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 A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available. A microsecond is to one second, ...
boundaries. This effectively pads every machine cycle to four
clock cycle In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') is an electronic logic signal (voltage or current) which oscillates between a high and a low state at a constant frequency and ...
s, causing a minor loss of processing power and resulting in what Amstrad estimated to be an "effective clock rate" of "approximately 3.3 MHz".CPC464/664/6128 Firmware (Soft 968), Section 1


Memory

Amstrad CPCs are equipped with either 64 (CPC 464, CPC 664, 464plus, GX4000) or 128 (CPC 6128, 6128plus) KB of RAM.Technical Specification, CPC6128 Service Manual, p. 31., Amstrad Consumer Electronics Plc. 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 Bank switching is a technique used in computer design to increase the amount of usable memory beyond the amount directly addressable by the Processor (computing), processor instructions. It can be used to configure a system differently at diffe ...
.


Video

Underlying a CPC's video output is the unusual pairing of a
CRTC The Canadian Radio-television and Telecommunications Commission (CRTC; ) is a public organization in Canada tasked with the mandate as a regulatory agency tribunal for various electronic communications, covering broadcasting and telecommunic ...
(
Motorola 6845 The Motorola 6845, or MC6845, is a display controller that was widely used in 8-bit computers during the 1980s. Originally intended for designs based on the Motorola 6800 CPU and given a related part number, it was more widely used alongside v ...
or compatible) with a custom-designed
gate array A gate array is an approach to the design and manufacture of application-specific integrated circuits (ASICs) using a semiconductor device fabrication, prefabricated chip with components that are later interconnected into logic devices (e.g. NAN ...
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 An application-specific integrated circuit (ASIC ) is an integrated circuit (IC) chip customized for a particular use, rather than intended for general-purpose use, such as a chip designed to run in a digital voice recorder or a high-efficien ...
. 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). Increased screen size can be achieved by reprogramming the CRTC. The original CPC video hardware supports a colour palette of 27 colours, generated from
RGB The RGB color model is an additive color model in which the red, green, and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three ...
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). With the exception of the GX4000, all CPC models lack an RF television or
composite video Composite video, also known as CVBS (composite video baseband signal or color, video, blanking and sync), is an analog video format that combines image information—such as brightness (luminance), color (chrominance), and synchronization, int ...
output and instead shipped with a 6-pin RGB
DIN connector The DIN connector is an electrical signal connector that was standardized by the (DIN), the German Institute for Standards, in the mid 1950s, initially with three pins for mono, but when stereo connections and gear appeared in the late 1950s, v ...
, also used by Acorn computers, to connect the supplied Amstrad monitor. 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 SCART (also known as or , especially in France, 21-pin EuroSCART in marketing by Sharp Corporation, Sharp in Asia, Euroconector in Spain, EuroAV or EXT, or EIA Multiport in the United States, as an EIA interface) is a French-originated standard ...
television. External adapters for RF television were available as a first-party hardware accessory.


Audio

The CPC uses the General Instrument AY-3-8912
sound chip A sound chip is an integrated circuit (chip) designed to produce audio signals through digital, analog or mixed-mode electronics. Sound chips are typically fabricated on metal–oxide–semiconductor (MOS) mixed-signal chips that process a ...
, 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 An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power su ...
.
Stereo Stereophonic sound, commonly shortened to stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configurat ...
output is provided through a
headphones Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an ...
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 ''RoboCop'' is a 1987 American Science fiction film, science fiction action film directed by Paul Verhoeven and written by Edward Neumeier and Michael Miner. The film stars Peter Weller, Nancy Allen (actress), Nancy Allen, Dan O'Herlihy, Dani ...
''. The later Plus models incorporated a DMA engine in order to offload this processing.


Floppy disk drive

Amstrad uses Matsushita's 3" floppy disk drive ef: CPCWiki which was compatible with
Hitachi () is a Japanese Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1910 and headquartered in Chiyoda, Tokyo. The company is active in various industries, including digital systems, power and renewable ener ...
's existing 3" floppy disk format. 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. Each side has its own independent write-protect switch. 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 The IBM Personal Computer XT (model 5160, often shortened to PC/XT) is the second computer in the IBM Personal Computer line, released on March 8, 1983. Except for the addition of a built-in hard drive and extra expansion slots, it is very simi ...
,
PC/AT The IBM Personal Computer AT (model 5170, abbreviated as IBM AT or PC/AT) was released in 1984 as the fourth model in the IBM Personal Computer line, following the IBM PC/XT and its IBM Portable PC variant. It was designed around the Intel 802 ...
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 Disk density is a capacity designation on magnetic storage, usually floppy disks. Each designation describes a set of characteristics that can affect the areal density of a disk or the efficiency of the encoded data. Such characteristics includ ...
using modified frequency modulation. Discs were shipped in a paper sleeve or a hard plastic case resembling a
compact disc The compact disc (CD) is a Digital media, digital optical disc data storage format co-developed by Philips and Sony to store and play digital audio recordings. It employs the Compact Disc Digital Audio (CD-DA) standard and was capable of hol ...
"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. 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 ZX may refer to: Arts and entertainment * Kamen Rider ZX (pronounced "Zed-Cross"), the tenth fictional superhero in the "Kamen Rider" franchise * ''Mega Man ZX'', a video game for the Nintendo DS * ''ZX Tunes'', remastered soundtracks of the "Meg ...
), the few other computer systems to use them included the
Sega is a Japanese video game company and subsidiary of Sega Sammy Holdings headquartered in Tokyo. It produces several List of best-selling video game franchises, multi-million-selling game franchises for arcade game, arcades and video game cons ...
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

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. 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.


Peripherals


RS232 serial adapters

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 Protocol may refer to: Sociology and politics * Protocol (politics) Protocol originally (in Late Middle English, c. 15th century) meant the minutes or logbook taken at a meeting, upon which an agreement was based. The term now commonly refers to ...
in the device's own ROM, as well as terminal software to connect to British Telecom's
Prestel Prestel was the Brand#Brand names and trademark, brand name of a videotex service launched in the UK in 1979 by BT Group#Post Office Telecommunications, Post Office Telecommunications, a division of the British Post Office Limited#History, Po ...
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


BASIC and operating system

Like most home computers at the time, the CPC has its OS and a
BASIC interpreter A BASIC interpreter is an Interpreter (computing), interpreter that enables users to enter and run programs in the BASIC programming language, language and was, for the first part of the microcomputer era, the default Application software, applica ...
built in as
ROM Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * ...
. It uses Locomotive BASIC - an improved version of Locomotive Software's Z80 BASIC for the
BBC Micro The BBC Microcomputer System, or BBC Micro, is a family of microcomputers developed and manufactured by Acorn Computers in the early 1980s as part of the BBC's Computer Literacy Project. Launched in December 1981, it was showcased across severa ...
co-processor board. It is particularly notable for providing easy access to the machine's video and audio resources in contrast to the
POKE Poke may refer to: Arts, entertainment, and media * Poke (Ender's Game), Poke (''Ender's Game''), a fictional character * Poke (game), a two-player card game * Poke, a fictional bar owner in the television series ''Treme (season 2), Treme'' * The ...
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 Digital Research, Inc. (DR or DRI) was a privately held American software company created by Gary Kildall to market and develop his CP/M operating system and related 8-bit, 16-bit and 32-bit systems like MP/M, Concurrent DOS, FlexOS, Multiuser ...
's
CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/Intel 8085, 85-based microcomputers by Gary Kildall of Digital Research, Dig ...
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 The public domain (PD) consists of all the creative work to which no Exclusive exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly Waiver, waived, or may be inapplicable. Because no one holds ...
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 and Pascal, the majority of the CPC's software was written in native Z80
assembly language In computing, assembly language (alternatively assembler language or symbolic machine code), often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence bet ...
. 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 A logo (abbreviation of logotype; ) is a graphic mark, emblem, or symbol used to aid and promote public identification and recognition. It may be of an abstract or figurative design or include the text of the name that it represents, as in ...
, 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''

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 Roland (; ; or ''Rotholandus''; or ''Rolando''; died 15 August 778) was a Frankish military leader under Charlemagne who became one of the principal figures in the literary cycle known as the Matter of France. The historical Roland was mil ...
'' 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

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 Schneider Rundfunkwerke AG was a German manufacturer of mass market audio equipment. History The origins of the company trace to 1889 in Türkheim, Bavaria, Germany, when Felix Schneider founded a company manufacturing industrial woodworking tools ...
'', 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 The QWERTZ ( ) QWERTZU ( ), or QWERTZUIOP keyboard is a typewriter and keyboard layout widely used in Central and Southeast Europe. The name comes from the first six letters at the top left of the keyboard: ( ). Overview The main differ ...
" keyboard layout, Schneider marketed a small software program to reassign the keys as well as sticker labels for the keys. 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 The micro ribbon or miniature ribbon connector is a common type of electrical connector for a variety of applications, such as in computer and telecommunications equipment having many contacts. The connector contains two parallel rows of ...
type connectors instead of
edge connector An edge connector is the portion of a printed circuit board (PCB) consisting of signal trace, traces leading to the edge of the board that are intended to plug into a matching jack (connector), socket. The edge connector is a money-saving devic ...
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.


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 A graphical user interface, or GUI, is a form of user interface that allows user (computing), users to human–computer interaction, interact with electronic devices through Graphics, graphical icon (computing), icons and visual indicators such ...
(GUI) operating systems such as
SymbOS SYmbiosis Multitasking Based Operating System (SymbOS) is a Computer multitasking, multitasking operating system for Zilog Z80-based 8-bit computer systems. Unlike early 8-bit operating systems, SymbOS is based on a microkernel, which provides ...
. Internet sites devoted to the CPC have appeared from around the world featuring forums, news, hardware, software, programming and games. CPC
Magazines A magazine is a periodical literature, periodical publication, print or digital, produced on a regular schedule, that contains any of a variety of subject-oriented textual and visual content (media), content forms. Magazines are generally fin ...
appeared during the 1980s including publications in countries such as Britain, France, Spain, Germany,
Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...
, Australia, and
Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...
. Titles included the official Amstrad Computer User publication, as well as independent titles like ''
Amstrad Action ''Amstrad Action'' is a discontinued monthly magazine, which was published in the United Kingdom. It is about home computers from the Amstrad CPC range and later the GX4000 console. It is the first magazine published by Chris Anderson (TED), Chri ...
'', ''
Amtix! ''Amtix'' (stylized as ''AMTIX!'') is a magazine that originally reviewed Amstrad CPC computer software in the mid-1980s, published monthly by Newsfield Publications Ltd. Unlike ''Zzap!64'' and '' CRASH'' (its more successful sister publication ...
'', ''Computing with the Amstrad CPC'', '' CPC Attack'', 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 In computing, an emulator is Computer hardware, hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest''). An emulator typically enables the host system to run sof ...
authors the possibility to ship the CPC firmware with their programs.


Influence on other Amstrad machines

Amstrad followed their success with the CPC 464 by launching the
Amstrad PCW The Amstrad PCW series is a range of personal computers produced by United Kingdom, British company Amstrad from 1985 to 1998, and also sold under licence in Europe as the "Joyce" by the German electronics company Schneider Computer Division, Schn ...
word-processor range, another Z80-based machine with a 3" disk drive and software by
Locomotive Software Locomotive Software was a small British software house that did most of its development for Amstrad's home and small business computers of the 1980s. It was founded by Richard Clayton and Chris Hall on 14 February 1983. It wrote or contributed sign ...
. 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). 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 Sinclair Research Ltd is a British consumer electronics company founded by Clive Sinclair in Cambridge in the 1970s. In 1980, the company entered the home computer market with the ZX80 at £99.95, at that time the cheapest personal computer ...
"...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." which included the
ZX Spectrum The ZX Spectrum () is an 8-bit computing, 8-bit home computer developed and marketed by Sinclair Research. One of the most influential computers ever made and one of the all-time bestselling British computers, over five million units were sold. ...
, for £5 million. This included Sinclair's unsold stock of
Sinclair QL The Sinclair QL (for ''Quantum Leap'') is a personal computer launched by Sinclair Research in 1984, as an upper-end counterpart to the ZX Spectrum. The QL was the last desktop microcomputer from Sinclair Research aimed at the serious home use ...
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 tape drive (like the CPC 464) and, the following year, the
ZX Spectrum +3 ZX may refer to: Arts and entertainment * Kamen Rider ZX (pronounced "Zed-Cross"), the tenth fictional superhero in the "Kamen Rider" franchise * ''Mega Man ZX'', a video game for the Nintendo DS * ''ZX Tunes'', remastered soundtracks of the "Meg ...
, with a built-in
floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...
drive (similar to the CPC 664 and 6128), taking the 3" discs that Amstrad CPC machines used.


Production 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)


See also

* Amstrad CPC character set * Amstrad CP/M Plus character set * List of Amstrad CPC emulators * List of Amstrad CPC games * GX4000 *
SymbOS SYmbiosis Multitasking Based Operating System (SymbOS) is a Computer multitasking, multitasking operating system for Zilog Z80-based 8-bit computer systems. Unlike early 8-bit operating systems, SymbOS is based on a microkernel, which provides ...
(multitasking operating system)


Notes and references


External links


CPC-Wiki
(CPC specific Wiki containing further information)
CPC-Power

Unofficial Amstrad WWW Resource

New OS for the CPC
{{DEFAULTSORT:Amstrad Cpc Computer-related introductions in 1984 CPC Z80-based home computers Computers designed in the United Kingdom