Amstrad CPC 464
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| CPC 464 with the CTM640 colour monitor | |
| Specifications | |
|---|---|
| Developer | Amstrad |
| Manufacturer | Amstrad Consumer Electronics plc |
| Type | Home computer |
| Released | June 1984 |
| Discontinued | 1990 |
| Intro price | £249 with green monitor, £359 with colour monitor |
| CPU | Zilog Z80A at 4 MHz |
| Memory | 64 KB RAM |
| Storage | Built-in cassette deck, 1000 or 2000 baud |
| Display | 160 × 200 (16 colours), 320 × 200 (4) or 640 × 200 (2) from 27 |
| Sound | General Instrument AY-3-8912, three voices |
| ROM | 32 KB (operating system and Locomotive BASIC 1.0) |
| Power | 5 V DC from the monitor |
| OS / Firmware | Amstrad firmware with Locomotive BASIC 1.0 |
| Successor | Amstrad 464 Plus |
| Model no. | CPC 464 |
The Amstrad CPC 464 is an 8-bit home computer that Amstrad launched in the UK in June 1984. It has a Z80A processor, 64 KB of RAM and a cassette deck built into the keyboard unit, and it was sold as a complete system with either the GT64 green monitor (£249) or the CTM640 colour monitor (£359).[1] The monitor also supplies the computer's power. The CPC 464 was the first model of the CPC range and stayed in production until the 464 Plus replaced it in 1990.[1]
Power
[edit | edit source]The CPC 464 has no mains connection and no power supply of its own. Amstrad's specification gives the power supply as "Screen System: 240V AC 50Hz (keyboard and datacorder power supplied by screen system)", and the computer's 5 mm power socket is "supplied exclusively from screen".[2] Mains enters the monitor. The keyboard unit carries only low voltage; the CTM640 and GT64 contain the mains supply and a CRT, and need the precautions in CRT Discharge Procedure. Amstrad's own fault chart for a dead machine begins at the monitor and its mains fuse, then the DC lead, before it reaches the computer board.[3]
Hardware
[edit | edit source]Amstrad's specification lists a Z80A at 4 MHz, 64 KB of RAM with over 42 KB available to the user, 32 KB of ROM holding BASIC and the operating system, a 6845 CRT controller, a General Instrument AY-3-8912 sound chip (three voices, seven octaves) and an 8255 parallel interface.[2] The video memory shares the 64 KB of RAM. Because the CPU and the video logic share that memory, CPU memory accesses are held to microsecond boundaries, which pads each machine cycle to four clock cycles; Amstrad's firmware guide puts the effective clock rate at about 3.3 MHz.[1]
On the original main board the parts list names the Z8400APS CPU (IC111), the TMM-23256P-1950 ROM (IC103), the HK6845SP CRTC (IC108), the M5L8255AP-5 PIO (IC107), the 20RA043 gate array (IC116, Amstrad part 40007), eight HM4864U-2 DRAMs (IC117–124) and a 16 MHz crystal (X101).[4] Amstrad's later amendment manual lists a board with the AMS40010 gate array and KM4164B-15 DRAMs.[5]
Display
[edit | edit source]All three modes are 200 lines high and draw their colours from a palette of 27.[2]
| BASIC mode | Resolution | Colours | Text columns |
|---|---|---|---|
| 0 | 160 × 200 | 16 | 20 |
| 1 | 320 × 200 | 4 | 40 |
| 2 | 640 × 200 | 2 | 80 |
Main board versions
[edit | edit source]CPCWiki's catalogue of observed boards identifies four production versions of the CPC 464 main board by their silkscreened part number.[7]
| Version | Silkscreen | Size | Notes |
|---|---|---|---|
| 1 (©1983) | Z70100; 270100 MC0001A; Z70100 MC0001A | 405 × 155 mm | Old gate array under a cooling plate; its VCC2 is fed through two 12 Ω resistors, R138 and R139 |
| 2 (©1984) | Z70200 with MC0001A, MC0002A–D, MC0003A, MC0008B–D | 405 × 152 mm | Pads for both the old and the new gate array; connector for the 6128-style 2 × 10-pin membrane keyboard |
| 3 | Z70374 MC0044A/B, Z70375 MC0044D, Z70378 MC0046A | 240 × 150 or 238 × 145 mm | Same parts packed more tightly; joystick and stereo sockets moved to the left |
| 4, cost-down (©1988) | Z80329 MC0099A | 237 × 108 mm | 100-pin surface-mount gate array combining the old gate array, the CRTC and some floppy, DRAM and reset logic |
The Amstrad CPC 664 board is Z70205, and the 6128 boards are Z70210, Z70270, Z70290 and Z80330.[7]
Storage
[edit | edit source]The built-in cassette deck writes at 1K or 2K baud, chosen in software; the read speed is detected automatically and the motor is switched by software.[2] The deck has its own board, the cassette PCB, which also carries the audio amplifier and the motor relay; Amstrad's manual gives the mechanism parts list and alignment instructions.[4]
Amstrad's DDI-1 added a 3-inch disc drive with a plug-on interface, its own mains supply and AMSDOS and CP/M in an expansion ROM; the FD-1 is the second drive.[8]
Capacitors
[edit | edit source]The CPC 464 has fourteen electrolytic capacitors. Only C101 and C102 are on the main board; the other twelve are on the cassette PCB.[4] Values and locations are in the Amstrad CPC 464 Capacitor Replacement Guide.
Documentation
[edit | edit source]- Amstrad CPC 464 Service Manual – Amstrad's service manual for the CPC 464, CTM640 and GT64
- Amstrad CPC 464 / CPC 6128 / GT65 / CTM644 / MP3 / CT1 Service Manual Amendment – later board, with the 40010 gate array
- Amstrad DDI-1 / FD-1 Service Manual – the disc interface and drives
- Amstrad 464 Plus / 6128 Plus / GX4000 Service Manual – the 1990 successor
Related pages
[edit | edit source]- Amstrad CPC 464 Maintenance Guide
- Amstrad CPC 464 Troubleshooting Guide
- Amstrad CPC 464 Capacitor Replacement Guide
- Amstrad CPC 664 · Amstrad 6128
- CRT Discharge Procedure
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Wikipedia, "Amstrad CPC", sections "CPC 464" and "Processor". Retrieved 2026-10-01. Gives the June 1984 UK introduction, the launch prices, the 1990 replacement by the 464 plus, and the CPU memory-access timing.
- ↑ 2.0 2.1 2.2 2.3 Amstrad Consumer Electronics plc, CPC464 Micro Computer / CTM640 Colour Monitor / GT64 Green Monitor Service Manual, p. 2 "Technical Specification". Described at Amstrad CPC 464 Service Manual.
- ↑ Amstrad Consumer Electronics plc, CPC464 Micro Computer / CTM640 Colour Monitor / GT64 Green Monitor Service Manual, p. 9 "CPC464 Basic Hardware Analysis". Described at Amstrad CPC 464 Service Manual.
- ↑ 4.0 4.1 4.2 Amstrad Consumer Electronics plc, CPC464 Micro Computer / CTM640 Colour Monitor / GT64 Green Monitor Service Manual, p. 17 "CPC464 Electrical Parts List". Described at Amstrad CPC 464 Service Manual.
- ↑ Amstrad plc, CPC464 / CPC6128 / GT65 / CTM644 / MP3 / CT1 Amendment Service Manual, p. 3 "CPC464 Electrical Parts List". Described at Amstrad CPC 464 / CPC 6128 / GT65 / CTM644 / MP3 / CT1 Service Manual Amendment.
- ↑ Wikipedia, "Amstrad CPC 464". Retrieved 2026-10-01. Gives the screen modes by BASIC mode number.
- ↑ 7.0 7.1 CPCWiki, "Mainboard Versions". Retrieved 2026-10-01. Community catalogue of board markings, sizes and per-version changes, compiled from photographed boards.
- ↑ Amstrad Consumer Electronics plc, DDI1 / FD1 Service Manual, p. 2 "Specifications". Described at Amstrad DDI-1 / FD-1 Service Manual.