Amstrad 464 Plus
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| 464 Plus with the CM14 colour monitor and paddle controller (service manual cover) | |
| Specifications | |
|---|---|
| Manufacturer | Amstrad plc |
| Type | Home computer |
| Released | 1990 |
| Intro price | £229 with MM12 monochrome monitor, £329 with CM14 colour monitor |
| CPU | Zilog Z80A at 4 MHz |
| Memory | 64 KB RAM |
| Storage | Built-in cassette deck |
| Display | 160 × 200 (16 colours), 320 × 200 (4) or 640 × 200 (2) from 4,096 |
| Sound | General Instrument AY-3-8912, three voices |
| Graphics | Amstrad ASIC (AMS40489) emulating the 6845 and 8255 |
| ROM | None on the board; firmware and BASIC on a 128 KB cartridge |
| Input | 74-key keyboard |
| Power | 5 V DC from the MM12 or CM14 monitor |
| Dimensions | 398 × 46 × 297 mm |
| OS / Firmware | Locomotive BASIC 1.1 and firmware v4 (cartridge) |
| Predecessor | Amstrad CPC 464 |
| Model no. | 464 Plus |
The Amstrad 464 Plus is the cassette-based model of Amstrad's 1990 Plus range, which replaced the Amstrad CPC 464. It keeps the CPC's Z80A, 64 KB of RAM and built-in cassette deck, and adds a custom ASIC with hardware sprites, a 4,096-colour palette, DMA-driven sound and a cartridge slot. The computer has no firmware ROM on its board: the operating system and BASIC come on the cartridge supplied with it. Amstrad launched the range at a Paris press conference in 1990 at £229 with the MM12 monochrome monitor and £329 with the CM14 colour monitor.[1][2] The 6128 Plus is its disc-drive sibling, and the GX4000 console uses the same chip set without a keyboard; all three are covered by one Amstrad service manual.[3]
History
[edit | edit source]New Computer Express reported the range in August 1990 after a launch in Paris. Amstrad restyled the case, changed the expansion connector so that older peripherals need an adapter, and supplied a cartridge holding BASIC and the racing game Burnin' Rubber.[1] Wikipedia gives the public introduction as September 1990 and records that the range sold poorly and was soon discontinued.[2]
Hardware
[edit | edit source]Amstrad's specification lists a Z80A at 4 MHz, 64K of RAM with over 41K free in BASIC, a 128K ROM cartridge with the BASIC firmware and Burnin' Rubber, the AY-3-8912 sound chip and an ASIC of 18,000 gates that emulates the 6845 video controller and the 8255 parallel interface and holds 16,000 bits of sprite data.[3] In BASIC the display modes are those of the CPC 464, with 27 colours. Cartridge games can use 16 hardware sprites and a palette of 4,096 colours, with soft scrolling, split screen, raster interrupts and DMA sound.[3]
| Ref | Part | Amstrad part no. |
|---|---|---|
| IC101 | AMS40489 ASIC | 40489 |
| IC102 | Z8400AB1N (Z80A) | 40080 |
| IC108 | MC74HC4051N | 270752 |
| IC109 | LA6393D | 270997 |
| IC110, IC111 | KM41464AP-12 DRAM | 40239 |
| IC114 | AY-3-8912 | 40001 |
| IC115 | AMS40464 | 40464 |
| IC116 | PC74HCT02P | 270999 |
| IC301 | LA6324 | 170112 |
The parts list gives the crystal X102 as a 40 MHz CXO-824C and the main board as PCB ASSY MC0122, the same assembly listed for the 6128 Plus.[3]
Connectors
[edit | edit source]| Socket | Use |
|---|---|
| 3.5 mm stereo jack | External amplifier |
| Two 9-pin D-type | Digital paddles or joysticks |
| 15-pin D-type | IBM-standard analogue joystick |
| RJ11 | Light gun |
| 25-way D-type | 8-bit Centronics printer |
| 50-way Amphenol-style | Full Z80 bus for expansion |
| 8-pin DIN | RGB, sync, luminance and stereo sound to the monitor |
| 5 mm socket | 5 V supply from the monitor |
The edge connectors of the older CPCs were replaced by these connectors, so CPC 464 peripherals need an adapter.[1][2] Amstrad's user instructions say the expansion, printer and second-drive connectors keep their functions but may use a different connector.[4]
Power
[edit | edit source]The 464 Plus has no mains input of its own. It takes 5 V through a 5 mm socket from the monitor, the MM12 (240 V AC in the UK, 220 V in Europe) or the CM14 (220–240 V AC).[3] The monitor's front lead has an 8-pin DIN plug for video and sound and a smaller plug for the 5 V supply.[4] The parts list gives the DC jack as J104, HEC0470-01-640.[3] The monitors hold mains voltage and a CRT; see CRT Discharge Procedure.
Amstrad's user instructions say the cartridge must be fitted or removed only with the computer's slide switch off, and that the computer must not be run without a cartridge.[4] With the BASIC cartridge fitted, a working machine starts with "Amstrad Microcomputer (v4)" and the 1985 Amstrad and Locomotive Software copyright line.[4]
Cassette deck
[edit | edit source]The deck is a TN-21ZH-754 (part 270775). The parts list also gives the main belt (270807), an "RF belt" (270805) and the motor (270858), and the cassette relay RY301 (G4S-1112P-1-B-19). Azimuth is set against Amstrad's MTT-113 test tape.[3] The procedures are in the Amstrad 464 Plus Maintenance Guide.
Repair guides
[edit | edit source]- Amstrad 464 Plus Maintenance Guide – opening the case, the cassette deck, the luminance adjustment and the cartridge slot
- Amstrad 464 Plus Troubleshooting Guide – power, video, cartridge and tape faults
- Amstrad 464 Plus Capacitor Replacement Guide – the fourteen electrolytic capacitors from the parts list
The 6128 Plus shares the main board; its own pages cover the disc drive.
Documentation
[edit | edit source]- Amstrad 464 Plus / 6128 Plus / GX4000 Service Manual – Amstrad's service manual for the Plus range and the MM12 and CM14 monitors
- The 464 Plus & 6128 Plus User Instructions are on archive.org (456 pages)
Related pages
[edit | edit source]- Amstrad 6128 Plus · Amstrad CPC 464 · Amstrad 6128
- CRT Discharge Procedure · Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Stuart Anderton, "Console and CPC Pluses take 8-bits into the '90s", New Computer Express no. 93 (August 1990). Transcribed at CPCrulez. Retrieved 2026-10-01. Launch prices, the changed expansion connector, the 6128 Plus's missing cassette port, the cartridge with BASIC and Burnin' Rubber.
- ↑ 2.0 2.1 2.2 Wikipedia, "Amstrad CPC", sections "The plus range" and "464 plus, 6128 plus". Retrieved 2026-10-01. Public introduction in September 1990, the absence of an on-board ROM, the firmware on cartridge, and the micro-ribbon connectors.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Amstrad plc, 464 PLUS Home Computer / 6128 PLUS Home Computer / GX4000 Games Console / MM 12 Monochrome Monitor / CM 14 Colour Monitor Service Manual. Described at Amstrad 464 Plus / 6128 Plus / GX4000 Service Manual. 464 Plus technical specification p. 3; electrical adjustments p. 4; PCB views pp. 5–6; electrical parts list p. 14.
- ↑ 4.0 4.1 4.2 4.3 Amstrad plc, 464 Plus & 6128 Plus User Instructions (1990), "Installation Notes", "Compatibility" and chapter 1 pp. 2–3. Scan at archive.org. Retrieved 2026-10-01.