Amstrad 6128 Plus
The Amstrad 6128 Plus is the disc-based model of Amstrad's 1990 Plus range and the successor to the CPC 6128. It has 128 KB of RAM, a built-in 3-inch disc drive and CP/M Plus, on the same main board as the Amstrad 464 Plus, with the Plus range's ASIC, cartridge slot and new connectors. Amstrad launched it in 1990 at £329 with the MM12 monochrome monitor and £429 with the CM14 colour monitor; it has no cassette port.[1][2]
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| 6128 Plus with a paddle controller (photo: Thomas Vogt, CC BY 4.0) | |
| Specifications | |
|---|---|
| Manufacturer | Amstrad plc |
| Type | Home computer |
| Released | 1990 |
| Intro price | £329 with MM12 monochrome monitor, £429 with CM14 colour monitor |
| CPU | Zilog Z80A at 4 MHz |
| Memory | 128 KB RAM in two 64 KB banks |
| Storage | Built-in 3-inch disc drive (EME-157) |
| 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); CP/M Plus on disc |
| Predecessor | Amstrad CPC 6128 |
| Model no. | 6128 Plus |
Hardware
editAmstrad's specification lists a Z80A at 4 MHz; 128K of RAM in two 64K banks, with over 41K free in BASIC and 61K available to CP/M Plus; a 128K ROM cartridge with the BASIC firmware and Burnin' Rubber; the AY-3-8912; the 18,000-gate ASIC that emulates the 6845 and 8255 and holds the sprite data; a µPD765A disc controller; a built-in 3-inch 170K drive compatible with the CPC models; and a 36-way Amphenol connector for a second drive. The supplied disc holds CP/M Plus.[3]
| Ref | Part | Amstrad part no. |
|---|---|---|
| IC101 | AMS40489 ASIC | 40489 |
| IC102 | Z80A, printed "Z840GAB1N" | 40080 |
| IC103 | SED9420CAC | 171034 |
| IC104 | Z765APS disc controller | 40018 |
| IC105, IC106 | SN74LS38N | 190056 |
| IC107 | MC74HC14AN | 193024 |
| IC108 | MC74HC4051N | 270752 |
| IC109 | LA6393D | 270997 |
| IC110–IC113 | KM41464AP-12 DRAM | 40239 |
| IC114 | AY-3-8912 | 40001 |
| IC115 | AMS40464 | 40464 |
| IC116 | PC74HCT02P | (printed 170112) |
| FDD201 | Compact floppy disc drive EME-157 | 271611 |
The main board is PCB ASSY MC0122, as on the 464 Plus, with a 40 MHz crystal at X102.[3] The 6128 Plus fits four KM41464 DRAMs where the 464 Plus has two, and adds the disc controller and its support chips (IC103–IC107). The part number printed against IC116 is the one given for the 464 Plus's LA6324; the 464 Plus list gives PC74HCT02P as 270999.
Power
editThe specification lists only a 5 mm socket for a 5 V supply from the monitor, and the parts list gives the same DC jack (J104, HEC0470-01-640) as the 464 Plus.[3] The CPC 6128 needed a second 12 V lead for its drive; the 6128 Plus has none, and its specification lists no supply other than the 5 V. The monitors are the MM12 (240 V AC UK, 220 V Europe) and the CM14 (220–240 V AC).[3] They contain the mains supply and a CRT; see CRT Discharge Procedure.
Disc system
editThe drive is an EME-157 3-inch mechanism (FDD201), which Amstrad's specification describes as a 170K drive compatible with the CPC models.[3] Amstrad's user instructions tell owners never to switch the 6128 Plus on or off with a disc in the drive, not to eject a disc while it is being read or written, and to keep the drive section to the right of the monitor and not directly in front of it.[4] The service manual gives no mechanism procedures for the EME-157.
Connectors
editThe external sockets are those of the 464 Plus (stereo jack, two digital joystick ports, a 15-pin analogue joystick port, an RJ11 light-gun socket, a 25-way printer port, the 50-way expansion connector and the 8-pin DIN monitor socket), plus the 36-way second-drive connector. There is no cassette socket.[3][1] The details are on the 464 Plus page.
Repair guides
edit- Amstrad 6128 Plus Maintenance Guide – the disc drive, the luminance adjustment and the parts shared with the 464 Plus
- Amstrad 6128 Plus Troubleshooting Guide – start-up, disc and video faults
- Amstrad 6128 Plus Capacitor Replacement Guide – the ten electrolytic capacitors from the parts list
Documentation
edit- Amstrad 464 Plus / 6128 Plus / GX4000 Service Manual – specification, adjustment, board views, schematics and parts lists
- The 464 Plus & 6128 Plus User Instructions are on archive.org (456 pages)
Related pages
editReferences
edit- ↑ 1.0 1.1 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 removal of the cassette port from the 6128 Plus, and the cartridge with BASIC and Burnin' Rubber.
- ↑ Wikipedia, "Amstrad CPC", sections "The plus range" and "464 plus, 6128 plus". Retrieved 2026-10-01. Introduction in September 1990, the missing tape socket on the 6128 Plus, the absence of an on-board ROM and the v4 firmware on cartridge.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 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. 6128 Plus specification and electrical adjustment p. 15; PCB views pp. 16–17; mechanical exploded view and cabinet parts list p. 21; electrical parts list p. 22.
- ↑ Amstrad plc, 464 Plus & 6128 Plus User Instructions (1990), "Installation Notes", "Special Disc Operation Notes (6128)" and chapter 1 pp. 2–3. Scan at archive.org. Retrieved 2026-10-01.