Amstrad CPC

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Amstrad CPC 464


The Amstrad CPC was a series of 8-bit home computers produced by Amstrad during the 1980s and early 1990s. CPC stood for 'Colour Personal Computer', although it was possible to purchase a CPC with a green screen (GT65/66) as well as with the standard colour screen (CTM640).


The Schneider CPC664

The first machine, the CPC 464 was introduced in 1984. It was designed to be a direct competitor to the Commodore 64 and Sinclair ZX Spectrum systems. The CPC range was very successful, and over 3 million were sold during the machine's lifespan.

Outwardly, the most distinguishing features of Amstrad's offering were the matt black console case with sharp corners and narrowly rectangular form factor (the latter due to the built-in cassette tape deck (CPC 464) or floppy disk drive (CPC 664 and CPC 6128), the keyboard's distinctly coloured special keys (all the non-typewriter-standard keys on the 464 and 664), and the unique power supply hookup with one lead going from the monitor to the computer (or RF modulator) and, on disc-based machines, one lead going the other way. A television could be used with an optional adapter, and an optional tuner was available to turn the monitor into a TV.

The CPC family

The original CPC was sold in the following configurations:

* CPC 464 – Tape deck, 64 KB RAM, square-edged keyboard
* CPC 472 – Tape deck, 72 KB RAM (although the extra 8 KB of RAM could not be used because the chip was not connected, only soldered to a dummy PCB); produced in small numbers for the Spanish market to avoid a legal ruling requiring that all computers with 64 KB or less RAM must be localized to the Spanish language, including the keyboard and screen messages. The law was subsequently changed to include machines with more than 64 KB RAM so a localised version of the 472 also exists.
* CPC 664 – 3" Floppy disk drive, 64 KB RAM, bowed keyboard; short-lived model, quickly replaced by the better-specified 6128
* CPC 6128 – 3" Floppy disk drive, 128 KB RAM (accessed using bank switching), more PC-like keyboard

An external disk drive (DDI-1) was available for the 464, incorporating the DOS in an interface unit. A second drive (FD-1) could be added to both this and 664/6128 machines. Cassette recorders could also be connected to the 664 and 6128. By and large, the later versions were compatible with earlier machines, though there were some incompatibilities in undocumented features. Third-party hardware add-ons such as Romantic Robot's popular Multiface allowed DIY backup of most tape software to disk.

Most games, especially in the early years, targeted the 64 KB RAM 464 and 664 models. However, an increasing number of applications and demos made use of the extra memory of the 6128 as time went on, to the extent that much CPC software from the 1990s will not run on an unexpanded 464/664. RAM expansions were available, the most popular being produced by dk'Tronics.

The memory layout of the system allowed the CPCs to run CP/M 2.2 and CP/M software adapted especially for the machines' terminal emulation was not uncommon. An Amstrad-specific variant of CP/M 3.1 (aka CP/M Plus) was shipped with the 6128.