Amstrad CPC
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The Amstrad CPC (short for ''Colour Personal Computer'') is a series of
8-bit In computer architecture, 8-bit Integer (computer science), integers or other Data (computing), data units are those that are 8 bits wide (1 octet (computing), octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) arc ...
home computers produced by
Amstrad Amstrad was a British electronics company, founded in 1968 by Alan Sugar at the age of 21. The name is a contraction of Alan Michael Sugar Trading. It was first listed on the London Stock Exchange in April 1980. During the late 1980s, Amstrad ...
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 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 the Guinness ...
and the Sinclair
ZX Spectrum The ZX Spectrum () is an 8-bit computing, 8-bit home computer that was developed by Sinclair Research. It was released in the United Kingdom on 23 April 1982, and became Britain's best-selling microcomputer. Referred to during development as t ...
, where it successfully established itself primarily in the United Kingdom, France, Spain, and the German-speaking parts of Europe. The series spawned a total of six distinct models: The ''CPC464'', ''CPC664'', and ''CPC6128'' were highly successful competitors in the European home computer market. The later ''464plus'' and ''6128plus'', intended to prolong the system's lifecycle with hardware updates, were considerably less successful, as was the attempt to repackage the ''plus'' hardware into a game console as the ''GX4000''. The CPC models' hardware is based on the Zilog Z80A CPU, complemented with either 64 or 128 KB of
RAM Ram, ram, or RAM may refer to: Animals * A male sheep * Ram cichlid, a freshwater tropical fish People * Ram (given name) * Ram (surname) * Ram (director) (Ramsubramaniam), an Indian Tamil film director * RAM (musician) (born 1974), Dutch * ...
. 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/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...
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 original range

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 that was developed by Sinclair Research. It was released in the United Kingdom on 23 April 1982, and became Britain's best-selling microcomputer. Referred to during development as t ...
series,
Commodore 64 The Commodore 64, also known as the C64, is an 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 the Guinness ...
, and
BBC Micro The British Broadcasting Corporation Microcomputer System, or BBC Micro, is a series of microcomputers and associated peripherals designed and built by Acorn Computers in the 1980s for the BBC Computer Literacy Project. Designed with an emphas ...
relied on the use of the domestic
television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
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 Disk storage (also sometimes called drive storage) is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is ...
. 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, an ...
, but in the home computer space, it predated the
Macintosh The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc., Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and ...
by almost a year. 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. In 1968, he started what would later become his largest business venture, consumer electronics com ...
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
Sinclair 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-co ...
and
ZX Spectrum The ZX Spectrum () is an 8-bit computing, 8-bit home computer that was developed by Sinclair Research. It was released in the United Kingdom on 23 April 1982, and became Britain's best-selling microcomputer. Referred to during development as t ...
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. It can be a part of an automotive entertainment system, a part of a ...
. It was introduced in June 1984 in the UK. Initial suggested retail prices for the CPC464 were GBP£249.00/DM899.00 with a green screen and GBP£359.00/DM1398.00 with a colour monitor. Following the introduction of the CPC6128 in late 1985, suggested retail prices for the CPC464 were cut by GBP£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.


CPC664

The CPC664 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 CPC664 were GBP£339.00/DM1198.00 with a green screen and GBP£449.00/DM1998.00 with a colour monitor. After the successful release of the CPC464, 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 CPC664, 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 CPC664 complemented the CPC464 which was neither discontinued nor reduced in price. Compared to the CPC464, the CPC664'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 CPC464's multicoloured keyboard, the CPC664's keys are kept in a much quieter grey and pale blue colour scheme. The back of the CPC664 main unit features the same connectors as the CPC464, with the exception of an additional 12V power lead. Unlike the CPC464's cassette tape drive that could be powered off the main unit's 5V voltage, the CPC664'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 CPC664 was only produced for approximately six months. In late 1985, when the CPC6128 was introduced in Europe, Amstrad decided not to keep three models in the line-up, and production of the CPC664 was discontinued.


CPC6128

The CPC6128 features 128 KB RAM and an internal 3-inch floppy disk drive. Aside from various hardware and firmware improvements, one of the CPC6128's most prominent features is the compatibility with the CP/M+ operating system that rendered it attractive for business uses. The CPC6128 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 CPC664 in the CPC model line-up. Initial suggested retail prices for the CPC6128 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 CPC6128 in the model line-up, and production of the CPC6128 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 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 cartridges up to 4
Mbit The megabit is a multiple of the unit bit for digital information. The prefix mega (symbol M) is defined in the International System of Units (SI) as a multiplier of 106 (1 million), and therefore :1 megabit = = = 1000 kilobits. The megabit h ...
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. 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 Commodore Amiga and Sega Mega Drive 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.


464plus, 6128plus

The ''464plus'' and ''6128plus'' models were intended as "more sophisticated and stylish" replacements of the CPC464 and CPC6128. Based on the redesigned plus hardware platform, they share the same base characteristics as their predecessors: The 464plus is equipped with 64 KB RAM and a cassette tape drive, the 6128plus features 128 KB RAM and a 3" floppy disk drive. Both models share a common case layout with a keyboard taken over from the CPC6128 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 CPC6128. As a result, a wide range of extensions for the original CPC range are connector-incompatible with the 464plus and 6128plus. 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 464plus and the 6128plus do not contain a firmware. Instead, Amstrad provided the firmware for both models via the ROM extension facility, contained on the included ''Burnin' Rubber and Locomotive BASIC'' cartridge. This resulted in reduced hardware localization cost (only some select key caps and case labels had to be localized) with the added benefit of a rudimentary copy protection mechanism (without a firmware present, the machine itself could not copy a game cartridge's content). 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 CPC6128's ''V3'' firmware. Both the 464plus and the 6128plus were introduced to the public in September 1990. Initial suggested retail prices were / with a monochrome monitor and / with a colour monitor for the 464plus, 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 controllers and the racing game ''Burnin' Rubber''.


Special models and clones


CPC472

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 ''CPC472'', a modified version of the CPC464. Its main differences are a small additional daughter board containing a CPC664 ROM chip and an 8 KB memory chip, and a keyboard with a ñ key (although some of them were temporarily manufactured without the ñ key). The sole purpose of the 8 KB memory chip (which is not electrically connected to the machine, so consequently rendered unusable) is to increase the machine's total memory specs to 72 KB in order to circumvent the import tax. Some months later, Spain joined the European Communities by the
Treaty of Accession 1985 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 o ...
and the import tax was suppressed, so Amstrad added the ñ key for the 464 and production of the CPC472 was discontinued.


KC compact

The ' ("" - which means "small computer" - being a rather literal German translation of the English "microcomputer") is an unofficial clone of the Amstrad CPC built by
East Germany East Germany, officially the German Democratic Republic (GDR; german: Deutsche Demokratische Republik, , DDR, ), was a country that existed from its creation on 7 October 1949 until its dissolution on 3 October 1990. In these years the state ...
's ' 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 memory and a CPC6128's firmware customized to the modified hardware, including an unmodified copy of Locomotive BASIC 1.1. The KC compact is the last 8-bit computer produced in East Germany. Due to the
German reunification German reunification (german: link=no, Deutsche Wiedervereinigung) was the process of re-establishing Germany as a united and fully sovereign state, which took place between 2 May 1989 and 15 March 1991. The day of 3 October 1990 when the Ge ...
happening at the time of the release only a very small number of systems were sold.


Aleste 520EX

In 1993, Omsk, Russia based company Patisonic released the Aleste 520EX, a computer highly compatible with the Amstrad CPC6128. It could also be switched into an MSX mode. An expansion board named ''Magic Sound'' allowed to play Scream Tracker files.


Reception

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 unit ...
'' 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 Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples wer ...
A processor, clocked at 4 
MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...
.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 boundaries. This effectively pads every machine cycle to four clock cycles, causing a minor loss of processing power and resulting in what Amstrad estimated to be an "effective clock rate" of "approximately 3.3 MHz".CPC464/664/6128 Firmware (Soft 968), Section 1


Memory

Amstrad CPCs are equipped with either 64 (CPC464, CPC664, 464plus, GX4000) or 128 (CPC6128, 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 instructions. It can be used to configure a system differently at different times; for example ...
.


Video

Underlying a CPC's video output is the unusual pairing of a
CRTC The Canadian Radio-television and Telecommunications Commission (CRTC; french: Conseil de la radiodiffusion et des télécommunications canadiennes, links=) is a public organization in Canada with mandate as a regulatory agency for broadcasti ...
( Motorola 6845 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 prefabricated chip with components that are later interconnected into logic devices (e.g. NAND gates, flip-flops, etc.) according ...
to generate a pixel display output. CPC6128s later in production as well as the models from the plus range integrate both the CRTC and the gate array's functions with the system's ASIC. Three built-in display resolutions are available: 160×200 pixels with 16 colours ("Mode 0", 20 text columns), 320×200 pixels with 4 colours ("Mode 1", 40 text columns), and 640×200 pixels with 2 colours ("Mode 2", 80 text columns). 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 addi ...
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 is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels) a ...
output and instead shipped with a 6-pin RGB
DIN connector The DIN connector is an electrical connector that was standardized by the ' (DIN), the German Institute for Standards, in the early 1970s. The male DIN connectors (plugs) feature a 13.2 mm diameter metal shield with a notch that limits the ...
, 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 in Asia, Euroconector in Spain, EuroAV or EXT, or EIA Multiport in the United States, as an EIA interface) is a French-originated standard and associated 21- ...
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 ...
, 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 may increase the power significantly, or its main effect may be to boost the v ...
.
Stereo Stereophonic sound, or more commonly 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 configuration ...
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 au ...
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. is a vehicular combat racing game, originally released as an arcade video game by Taito in 1988. It is sometimes seen as a spiritual successor to Taito's earlier '' Full Throttle''. The player assumes the role of a police officer named Tony Gib ...
'', ''
Meltdown Meltdown may refer to: Science and technology * Nuclear meltdown, a severe nuclear reactor accident * Meltdown (security vulnerability), affecting computer processors * Mutational meltdown, in population genetics Arts and entertainment Music * Me ...
'', and '' RoboCop''. 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'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 AMSDOS is a disk operating system for the 8-bit Amstrad CPC Computer (and various clones). The name is a contraction of Amstrad Disk Operating System. AMSDOS first appeared in 1984 on the CPC 464, with added 3 inch disk drive, and then on the ...
format, comprising 2 KB directory and 178 KB storage) for a total of 360 KB per disk. The interface with the drives is a 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 simila ...
,
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 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 include ...
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 include ...
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 that was co-developed by Philips and Sony to store and play digital audio recordings. In August 1982, the first compact disc was manufactured. It was then rele ...
"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), the few other computer systems to use them included the Sega SF-7000 and CP/M systems such as the Tatung Einstein and
Osborne Osborne may refer to: * Osborne (name) Places Australia * Osborne, South Australia (disambiguation), places associated with the suburb in the Adelaide metropolitan area * Osborne, New South Wales, a rural community in the Riverina region Can ...
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 The Atari joystick port is a computer port used to connect various gaming controllers to game console and home computer systems in the 1970s to the 1990s. It was originally introduced on the Atari 2600 in 1977 and then used on the Atari 400 an ...
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 CPC464 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), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technolog ...
in the device's own ROM, as well as
terminal Terminal may refer to: Computing Hardware * Terminal (electronics), a device for joining electrical circuits together * Terminal (telecommunication), a device communicating over a line * Computer terminal, a set of primary input and output dev ...
software to connect to British Telecom's
Prestel Prestel (abbrev. from press telephone), the brand name for the UK Post Office Telecommunications's Viewdata technology, was an interactive videotex system developed during the late 1970s and commercially launched in 1979. It achieved a maxim ...
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 Pace or paces may refer to: Business *Pace (transit), a bus operator in the suburbs of Chicago, US * Pace Airlines, an American charter airline *Pace Foods, a maker of a popular brand of salsa sold in North America, owned by Campbell Soup Compan ...
. 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 BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
interpreter 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 Locomotive Basic is a proprietary dialect of the BASIC programming language written by Locomotive Software on the Amstrad CPC (where it was built-in on ROM) and the later Locomotive BASIC-2 as a GEM application on the Amstrad PC1512 and 1640. ...
- an improved version of Locomotive Software's Z80 BASIC for the
BBC Microcomputer The British Broadcasting Corporation Microcomputer System, or BBC Micro, is a series of microcomputers and associated peripherals designed and built by Acorn Computers in the 1980s for the BBC Computer Literacy Project. Designed with an emphasi ...
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''), a fictional character * Poke (game), a two-player card game * Poke, a fictional bar owner in the television series '' Treme'' * The Poke, a British satirical website Fo ...
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 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 DOS, DOS Plus, DR DOS and ...
'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/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...
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 A creative work is a manifestation of creative effort including fine artwork (sculpture, paintings, drawing, sketching, performance art), dance, writing (literature), filmmaking, ...
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. 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 it represents as in a wordma ...
, 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 (; frk, *Hrōþiland; lat-med, Hruodlandus or ''Rotholandus''; it, Orlando 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 ...
'' 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'', 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 CPC464 and CPC664 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. 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 CPC6128 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 traces leading to the edge of the board that are intended to plug into a matching socket. The edge connector is a money-saving device because it only requires a sing ...
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 CPC464 and CPC6128, 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 The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
(GUI) operating systems such as SymbOS. Internet sites devoted to the CPC have appeared from around the world featuring forums, news, hardware, software, programming and games. CPC
Magazines A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combination ...
appeared during the 1980s including publications in countries such as Britain, France, Spain, Germany,
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
, Australia, and Greece. Titles included the official Amstrad Computer User publication, as well as independent titles like ''Amstrad Action'', ''Amtix!'', ''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 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 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). 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." which included the
ZX Spectrum The ZX Spectrum () is an 8-bit computing, 8-bit home computer that was developed by Sinclair Research. It was released in the United Kingdom on 23 April 1982, and became Britain's best-selling microcomputer. Referred to during development as t ...
, for £5 million. This included Sinclair's unsold stock of Sinclair QLs and Spectrums. Amstrad made more than £5 million on selling these surplus machines alone. Amstrad launched two new variants of the Spectrum: the ZX Spectrum +2, based on the ZX Spectrum 128, with a built-in 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

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_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: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: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 computer system emulators#Amstrad CPC, List of Amstrad CPC emulators * List of Amstrad CPC games * GX4000 * FutureOS http://www.FutureOS.de * SymbOS (multitasking operating system)


Notes and references


External links


CPC-Wiki
(CPC specific Wiki containing further information)
Unofficial Amstrad WWW Resource
*
New OS for the CPC
{{DEFAULTSORT:Amstrad Cpc Amstrad CPC, Computer-related introductions in 1984 Amstrad, CPC Z80-based home computers Computers designed in the United Kingdom