Josh: New page from Amstrad's Plus range service manual and user instructions

2026-10-01T23:15:03Z

New page from Amstrad's Plus range service manual and user instructions

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{{Infobox computer
| name = Amstrad 464 Plus
| image = [[File:Amstrad 464 Plus (service manual cover).png|260px|frameless]]
| caption = 464 Plus with the CM14 colour monitor and paddle controller (service manual cover)
| manufacturer = Amstrad plc
| type = Home computer
| release date = 1990
| price = £229 with MM12 monochrome monitor, £329 with CM14 colour monitor
| cpu = Zilog Z80A at 4 MHz
| memory = 64 KB RAM
| rom = None on the board; firmware and BASIC on a 128 KB cartridge
| storage = Built-in cassette deck
| graphics = Amstrad ASIC (AMS40489) emulating the 6845 and 8255
| display = 160 × 200 (16 colours), 320 × 200 (4) or 640 × 200 (2) from 4,096
| sound = General Instrument AY-3-8912, three voices
| input = 74-key keyboard
| power = 5 V DC from the MM12 or CM14 monitor
| dimensions = 398 × 46 × 297 mm
| os = Locomotive BASIC 1.1 and firmware v4 (cartridge)
| predecessor = [[Amstrad CPC 464]]
| model = 464 Plus
}}
<templatestyles src="Template:StyledTable/styles.css" />
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.<ref name="nce93">Stuart Anderton, "Console and CPC Pluses take 8-bits into the '90s", ''New Computer Express'' no. 93 (August 1990). Transcribed at [https://cpcrulez.fr/people-cpc-console_and_CPC_pluses_take_8-bits_into_the_90s.htm 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''.</ref><ref name="wpcpc">Wikipedia, [https://en.wikipedia.org/wiki/Amstrad_CPC "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.</ref> 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.<ref name="smplus">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.</ref>

== History ==

''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''.<ref name="nce93" /> Wikipedia gives the public introduction as September 1990 and records that the range sold poorly and was soon discontinued.<ref name="wpcpc" />

== Hardware ==

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.<ref name="smplus" /> 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.<ref name="smplus" />

{| class="wikitable styled-table" style="width:70%; text-align:left;"
|+'''464 Plus integrated circuits (parts list, p. 14)'''
! 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.<ref name="smplus" />

[[File:Amstrad 464 Plus main PCB layout.png|thumb|360px|The MC0122 main board, top view (service manual p. 5)]]

== Connectors ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''464 Plus external sockets (specification, p. 3)'''
! 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.<ref name="nce93" /><ref name="wpcpc" /> Amstrad's user instructions say the expansion, printer and second-drive connectors keep their functions but may use a different connector.<ref name="uiplus">Amstrad plc, ''464 Plus & 6128 Plus User Instructions'' (1990), "Installation Notes", "Compatibility" and chapter 1 pp. 2–3. Scan at [https://archive.org/details/amstrad-464-plus-6128-plus-user-instructions archive.org]. Retrieved 2026-10-01.</ref>

== Power ==

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).<ref name="smplus" /> The monitor's front lead has an 8-pin DIN plug for video and sound and a smaller plug for the 5 V supply.<ref name="uiplus" /> The parts list gives the DC jack as J104, HEC0470-01-640.<ref name="smplus" /> 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.<ref name="uiplus" /> With the BASIC cartridge fitted, a working machine starts with "Amstrad Microcomputer (v4)" and the 1985 Amstrad and Locomotive Software copyright line.<ref name="uiplus" />

== Cassette deck ==

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.<ref name="smplus" /> The procedures are in the [[Amstrad 464 Plus Maintenance Guide]].

== Repair guides ==

* [[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 ==

* [[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 [https://archive.org/details/amstrad-464-plus-6128-plus-user-instructions archive.org] (456 pages)

== Related pages ==

* [[Amstrad 6128 Plus]] · [[Amstrad CPC 464]] · [[Amstrad 6128]]
* [[CRT Discharge Procedure]] · [[Capacitor Failure Symptoms]]

== References ==
<references />

{{Navbox-Amstrad|state=collapsed}}

[[Category:Amstrad]]

Amstrad 464 Plus - Revision history

Josh: New page from Amstrad's Plus range service manual and user instructions