Amstrad CPC

• 1. Introduction

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  The Amstrad CPC arrived in June 1984 with a retail price of £249 and a bold claim: that a home computer should look like a real computer. Alan Sugar, the founder of Amstrad, wanted a machine that resembled something you might see at an airport check-in desk, not what he dismissively called a "pregnant calculator" - a dig at the rubber-keyed ZX Spectrum that had dominated British living rooms. The CPC stood for Colour Personal Computer, and Amstrad sold it bundled with its own dedicated monitor, which also doubled as the machine's power supply. That was not a gimmick. It was a philosophy. Over the six years the series ran, the Amstrad CPC sold approximately three million units across the United Kingdom, France, Spain, the German-speaking parts of Europe, and Canada. Six distinct models carried the CPC name. Some sold spectacularly. Others barely lasted months. One was built in East Germany just weeks before the Berlin Wall fell. What made this 8-bit machine outlast so many of its competitors, and why did its final push collapse so completely?

• 2. The All-in-One Idea

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  Most home computers of the early 1980s required the buyer to assemble a patchwork of separate devices. The ZX Spectrum, the Commodore 64, the BBC Micro - all of them plugged into a domestic television set and connected to a separate tape recorder or disk drive. Amstrad's answer was to bundle everything into a single unit sold with its own screen. The idea was not entirely original; business machines and the Commodore PET had done it before. But no machine had brought the concept to the mid-range home computer market at the price points Amstrad was targeting. The CPC 464, the machine that launched the series, packed 64 KB of RAM and a cassette deck inside its keyboard chassis. A green-screen monitor came in at £249, while a colour monitor pushed the price to £359. When the CPC 6128 arrived in late 1985, Amstrad cut the 464's price by £50 to keep it competitive. The magazine Your Computer concluded that the machine offered "superior graphics and sound, an excellent Basic coupled with a flexible operating system" and that Amstrad's target of selling 200,000 units by the end of 1984 was realistic. A BYTE columnist writing in January 1985 called the 464 "the closest yet to filling" his criteria for a genuinely useful home computer, citing its good keyboard, 80-column text capability, inexpensive disk drive, and support for the CP/M operating system. The CPC 464 went on to sell more than two million units.

• 3. Models That Clicked and One That Didn't

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  On the 25th of April 1985, Amstrad introduced the CPC 664, a machine with 64 KB of RAM and an internal 3-inch floppy disk drive. Consumers had been asking for exactly that upgrade since the 464 launched. The 664 launched with a redesigned keyboard tilted toward the user and positioned deliberately as the lowest-cost CP/M 2.2 machine on the market. Its keys were rendered in a quiet grey and pale blue, a sharp contrast to the 464's multicoloured layout. The 664 lasted approximately six months. When the CPC 6128 arrived in Europe on the 15th of August 1985, Amstrad dropped the 664 from the line-up rather than carry three models simultaneously. The 6128 had already launched in the United States two months earlier, distributed by Indescomp, Inc. of Chicago - making it the first Amstrad product ever sold in the American market. With 128 KB of RAM and compatibility with the CP/M Plus operating system, the 6128 appealed to business users in a way neither of its predecessors quite managed. Its initial US price was $699 with a green-screen monitor. The short life of the 664 illustrates how quickly Amstrad moved: when a better machine was ready, the previous model was cut without sentiment. The 6128 stayed in production until 1990, when the plus range replaced it.

• 4. Under the Hood

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  Every model in the CPC series ran on the Zilog Z80A processor, clocked at 4 MHz. To prevent the CPU and the video logic from fighting over the same memory at the same moment - a conflict that would cause what engineers called "snowing" on screen - Amstrad constrained CPU memory access to occur on microsecond boundaries. The practical result was an effective clock rate that Amstrad itself estimated at approximately 3.3 MHz. The video hardware paired a Motorola 6845 chip with a custom gate array to produce three display modes: 160 by 200 pixels with 16 colours, 320 by 200 with 4 colours, or 640 by 200 with just 2 colours. Sound came from the General Instrument AY-3-8912 chip, delivering three channels through a 4-centimetre built-in speaker, with stereo output available through a 3.5 mm headphones jack. The 3-inch floppy drives used in the 664 and 6128 were Matsushita units, compatible with Hitachi's existing 3-inch format. Each side of a disk held 180 KB in AMSDOS format, giving a total of 360 KB per physical disk. The disks came in paper sleeves or hard plastic cases resembling compact disc jewel cases, and were more expensive than both 5.25-inch and 3.5-inch alternatives - a cost that contributed to the format being discontinued not long after the CPC itself.

• 5. Software and Language

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  Locomotive BASIC came built into the CPC's ROM and distinguished itself from competing implementations in practical ways. Where generic Microsoft BASIC required programmers to use POKE commands to access a machine's video and audio hardware, Locomotive BASIC gave direct, readable access to those resources. It also offered timed event handling through AFTER and EVERY commands, and built-in text windowing. For users who needed more, Digital Research's CP/M operating system shipped with the 664 and 6128, and was available for the 464 via the DDI-1 disk unit. The 64 KB machines received CP/M 2.2; the 128 KB machines added CP/M 3.1. Most CPC software was written in native Z80 assembly language. Popular assemblers included Hisoft's Devpac, Arnor's Maxam, and DAMS, which was widely used in France. Disk-based CPC machines also shipped with an interpreter for LOGO, the educational language. A C compiler was made available for the European market through Tandy Europe. The ROM expansion system let users access software from external 16 KB ROM chips via plug-in boxes attached to the rear expansion port. Applications sold on ROM included the Protext word processor and the MAXAM assembler. Software on ROM loaded faster than from disk or tape, but the feature was never documented in the user manual and went unmentioned in Amstrad's own marketing.

• 6. Clones, Variants, and Workarounds

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  During the August holidays of 1985, Spain introduced an import tax of 15,000 pesetas on any computer containing 64 KB of RAM or less, under Royal Decree 1215/1985 and 1558/1985. A separate law, Royal Decree 1250/1985, required all computers sold in Spain to have a Spanish keyboard. Amstrad's Spanish distributor Indescomp responded by creating the CPC 472: a modified CPC 464 fitted with a small daughter board containing a CPC 664 ROM chip and an 8 KB memory chip. That extra 8 KB chip was not electrically connected to the rest of the machine and was therefore completely unusable. Its sole purpose was to push the machine's stated memory total to 72 KB, clearing the tax threshold. A few months later Spain joined the European Communities under the Treaty of Accession 1985, the import tax was scrapped, and the 472 was quietly discontinued. In East Germany, VEB Mikroelektronik Mühlhausen built its own CPC clone called the KC compact in October 1989. The name derived from Kleincomputer - the German for small computer. It was largely compatible with CPC software and ran a customised version of the CPC 6128's firmware, including a copy of Locomotive BASIC 1.1 modified only in its startup banner. The KC compact was the last 8-bit computer introduced in East Germany. German reunification was already underway at the time of its release, and only a very small number of units were sold. In 1993, Patisonic of Omsk, Russia, released the Aleste 520EX, a machine highly compatible with the CPC 6128 that could also switch into an MSX mode.

• 7. The Schneider Partnership

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  In 1984, Amstrad lacked any distribution infrastructure in Germany, Austria, and Switzerland. Its solution was a partnership with Schneider Rundfunkwerke AG, a German company whose background in value-priced audio products mirrored Amstrad's own origins. Schneider created a dedicated division called Schneider Computer Division and sold the entire CPC range under the Schneider CPC brand. The hardware was identical, but Schneider's models carried several visible differences. The CPC 464 and 664 in Schneider trim used grey keys instead of the original coloured ones, though the keyboard layout remained British QWERTY. To add German QWERTZ input, Schneider sold a small software program to reassign keys alongside sticker labels. German EMC regulations were stricter than British ones, so all Schneider CPC models were fitted with internal metal shielding. The Schneider CPC 6128 also used micro-ribbon connectors rather than edge connectors, again to meet EMC requirements. Both of those design choices - the grey keyboard and the micro-ribbon connectors - eventually fed back into later Amstrad CPC hardware designs. The partnership ended in 1988 after Schneider declined to market Amstrad's AT-compatible PC range. Schneider sold off its remaining CPC stock and used the brand recognition it had built to launch its own PC products. Amstrad subsequently set up its own German subsidiary, Amstrad GmbH, to sell the CPC 464 and CPC 6128 directly in the German-speaking market, but never succeeded in establishing the Amstrad name there.

• 8. The Plus Range and a Hard Stop

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  In 1990, Amstrad launched the plus range under the conviction that the CPC platform could be salvaged with enough hardware upgrades. The redesigned video system gained 16 hardware sprites and soft scrolling. The colour palette jumped from a maximum of 16 simultaneous colours chosen from 27 to a maximum of 31 chosen from 4096. The sound chip gained an automatic DMA engine that handled complex audio effects without tying up the processor. The range included the 464 plus, the 6128 plus, and the GX4000 - a game console that stripped out the keyboard and mass storage to produce the barest possible version of the plus hardware. The GX4000 came bundled with two paddle controllers and the racing game Burnin' Rubber. The plus models replaced firmware ROM with a cartridge: the Burnin' Rubber and Locomotive BASIC cartridge that shipped with each machine contained the firmware for both models. This meant only select key caps and case labels needed localising for different markets, and it provided a rudimentary copy-protection mechanism - without firmware present, the machine could not copy a cartridge. Amstrad even sold a separate cartridge containing the original CPC 6128's V3 firmware for software that depended on it. None of it was enough. The plus range was built on an 8-bit CPU at a moment when buyers were gravitating toward the Amiga and the Mega Drive, the latter having launched only a few months before the plus range itself. The plus range failed commercially and was discontinued shortly after its 1990 introduction. Amstrad had given the CPC its best effort; the community it left behind kept programming for the platform for decades, eventually producing graphical user interface operating systems such as SymbOS, while dedicated magazines served readers in Britain, France, Spain, Germany, Denmark, Australia, and Greece throughout the 1980s.