Amstrad PCW 8256
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| PCW8256 monitor unit and keyboard at the Royal Museum, Edinburgh | |
| Specifications | |
|---|---|
| Manufacturer | Amstrad Consumer Electronics plc |
| Type | Word processor and CP/M personal computer |
| Released | September 1985 |
| Intro price | £399 plus VAT (UK launch) |
| CPU | Zilog Z80A (Z8400AP) at 4 MHz |
| Memory | 256 KB (eight 256K × 1 DRAMs), about 112 KB of it used as RAM disc |
| Storage | One 3-inch drive, 180 KB per side; space for a second drive |
| Display | Built-in green monochrome monitor, 90 × 32 characters, 720 × 256 pixels |
| Sound | Piezo buzzer |
| Ports / interface | Printer data and power, keyboard (4-pin DIN), expansion edge connector |
| Power | 220–240 V 50 Hz mains; supply in the monitor unit |
| OS / Firmware | LocoScript, CP/M Plus |
| Successor | Amstrad PCW 9512 |
| Model no. | PCW8256; sold in Germany as the Schneider Joyce |
The Amstrad PCW 8256 is a Z80-based word processor and CP/M computer launched by Amstrad in September 1985. It came as three units: a monitor unit holding the 12-inch green screen, the computer board, the power supply and a 3-inch disc drive; a separate keyboard; and a 9-pin dot matrix printer powered and driven from the monitor unit. It shipped with Locomotive Software's LocoScript word processor, CP/M Plus, Mallard BASIC and Dr. Logo.[1][2] Its larger sibling, the Amstrad PCW 8512, uses the same boards with 512 KB of RAM and a second, double-sided drive.[1]
History
[edit | edit source]Amstrad launched the PCW 8256 in the UK in September 1985 at £399 plus VAT, a price that included the printer and software, and sold it at first only through Dixons. The project was code-named "Joyce" during development, and Schneider sold the machine in Germany under that name. In the US it was offered at $799.[2] The PCW 8512 followed a few months later, and the Amstrad PCW 9512 arrived in 1987 with a new case, a paper-white screen and a daisywheel printer.[2][3]
Amstrad's service manual says the keyboard, the computer unit and the green monitor were designed in the UK and made in Korea.[1]
Specification
[edit | edit source]| Item | PCW8256 |
|---|---|
| Processor | Z80A |
| RAM | 256K, about 112K of it organised as RAM disc |
| Screen | Green monitor, 90 columns by 32 lines |
| Disc | One 3-inch "flip over" drive, 180K formatted per side; a second drive can be fitted |
| Keyboard | 82 keys, with its own custom microprocessor and a coiled cable to the monitor unit |
| Printer | About 20 cps letter quality, 90 cps draft (elite pitch); tractor feed and single-sheet loading |
| Options | CPS 8256 RS232C serial and Centronics parallel interface |
| Software | Word processing software, CP/M Plus with GSX, Mallard BASIC, Dr LOGO |
The screen is 720 × 256 pixels, each pixel twice as high as it is wide.[4] The user guide gives the mains supply as 220–240 V 50 Hz and asks for a 5 A fuse in a 13 A plug.[5]
Hardware
[edit | edit source]
The computer board (CPU PCB MC0015Q) sits in the monitor unit with the monitor board, which carries the switch-mode power supply.[1] The service manual's electrical parts list names these main parts:[1]
| Ref | Part | Amstrad part no. | Notes |
|---|---|---|---|
| IC101 | Amstrad 40028 | 171031 | Custom device on the CPU board |
| IC102 | Z8400AP | 40080 | Z80A processor |
| IC104–111 | TMM41257P-15 | 171032 | Eight 256K × 1 DRAMs (256K fitted) |
| IC201 | SED9420CAC | 171034 | |
| IC203 | µPD765AC-2 | 40018 | Floppy disc controller |
| IC701 | Amstrad 40026 | 171038 | Printer controller |
| IC801 | Amstrad 40027 | 171043 | Keyboard controller, in the keyboard |
| IC5001 | STK7308 | 170445 | Monitor board, power supply |
| IC5004 | AN78N24 | 171042 | Monitor board, power supply |
| X101 | 32.0 MHz crystal | 171063 |
The printer control section around the 40026 is on the CPU board; the printer itself holds only the mechanism and its driver board.[1][2] John Elliott's notes describe the PCW as having no boot ROM: at reset the hardware feeds the Z80 a fixed stream of bytes that builds a 256-byte boot program in RAM, and that program loads the first sector of the disc. Dot matrix and daisywheel PCWs use slightly different boot programs.[4] Without a disc the machine shows a blank screen and beeps; with a start-of-day disc a series of lines moves down the screen as the disc loads.[6][5]
Memory
[edit | edit source]The CPU board has positions for sixteen DRAMs, IC104–IC119. The PCW8256 fills IC104–IC111 with eight 256K chips; the PCW8512 fills all sixteen. Four links, A to D, tell the board which arrangement is fitted:[1]
| Memory (K) | DRAM size (K) | Link A | Link B | Link C | Link D | ICs fitted |
|---|---|---|---|---|---|---|
| 512 | 256 | off | on | off | on | IC104–119 |
| 256 | 256 | on | off | off | on | IC104–111 |
| 128 | 64 | off | on | on | off | IC104–119 |
| 128 | 256 | on | off | on | off | IC104–107 |
Community guidance for turning an 8256 into an 8512 is to fit the eight extra chips in the empty sockets and change the memory setting on the board, which varies with the board's date of manufacture, and to fit a double-sided CF2DD drive as drive B. The cables for the second drive are already present, but its cage and screws are not.[6] The RAM is handled in 16K blocks; Elliott gives a fully expanded PCW as 2 MB.[4]
Disc drive
[edit | edit source]The cabinet parts list gives the drive as a Compact Floppy Disc Drive EME-155 (part 190005). It takes 3-inch CF2 discs, which are turned over to use the second side.[1] The drive is belt-driven: Amstrad's spindle motor replacement procedure removes the drive belt, and the replacement is followed by setting the index period to 200 ±2 ms with VR201 on the drive's control board.[1] Amstrad told service agents not to repair drive mechanisms or their boards during the warranty period and supplied exchange mechanisms instead.[1]
Monitor and power supply
[edit | edit source]The monitor board (MM0010B) holds the switch-mode supply built round the STK7308 hybrid (IC5001), the deflection circuits and the mains input. The mains fuse F5001 is a 2 A time-lag, 250 V part (1400253). The CRT is a 340AXB31 (171020) with deflection yoke DY0271011401 and flyback transformer 2014001.[1] The supply's 12 V and 5 V outputs are set with VR5002 and VR5001; the Amstrad PCW 8256 Maintenance Guide gives the procedure.[1] The supply also feeds the printer, through a separate power cable that plugs into the Power Out socket on the back of the monitor unit.[5][6]
Printer and keyboard
[edit | edit source]The printer connects to the monitor unit by a 34-way ribbon cable and a separate power lead.[5] Amstrad lists the printer mechanism as one exchange assembly (171127) and gives a full mechanical parts list, including the print head assembly (171186), timing belt (171204), paper feed motor and head drive motor.[1] The ribbon is a cassette, Amstrad Printer Ribbon PR-1.[5]
The 82-key keyboard has its own controller, the Amstrad 40027, and plugs into a 4-pin DIN socket on the right-hand side of the monitor unit.[1][5] The keyboard board has three option links; fitting LK1 puts the keyboard into a self-test mode in which it sends test patterns continuously and the Shift Lock LED stays lit.[4] The 8256 and 8512 keyboards are marked 256K and 512K but are interchangeable.[6]
Expansion
[edit | edit source]The back of the monitor unit has an edge connector carrying the Z80 bus, used for the CPS 8256 serial and parallel interface, memory expansions, mice and other add-ons.[1][2] The connector looks like the CPC's but its pins are assigned differently, so CPC expansions cannot be used.[6]
Service documentation
[edit | edit source]- Amstrad PCW 8256 / PCW 8512 Service Manual: specification, drive flow charts and alignment, monitor and supply alignment, all board layouts and schematics, and the parts lists. Amstrad's notes say that full diagnostics need the R.P.3 diagnostic tool and that boards, drive mechanisms and printer mechanisms were normally exchanged.[1]
- Amstrad PCW 8256 / PCW 8512 User Guide: setting up, user troubleshooting, printer loading and ribbon changing, and two-drive operation.[5]
- Amstrad PCW Hardware Reference (John Elliott): ports, memory paging, the boot process and the keyboard protocol.[4]
Known faults
[edit | edit source]- A drive whose motor runs but whose disc does not turn, leaving a blank screen at start-up, usually has a perished belt. Community advice calls this the most common PCW fault.[6] See the Amstrad PCW 8256 Troubleshooting Guide and Floppy Drive Repair.
- Keyboards are no longer made, and printer ribbons are hard to find.[6]
- The power supply and the CRT share the monitor unit, so any work inside it means working near mains voltage and the tube's stored charge. See CRT Discharge Procedure.[1]
Gallery
[edit | edit source]-
Schneider Joyce, the PCW 8256 as sold in Germany -
Monitor board layout, with the mains area outlined -
CPU board Mk II
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Related pages
[edit | edit source]- Amstrad PCW 8256 Maintenance Guide · Amstrad PCW 8256 Troubleshooting Guide · Amstrad PCW 8256 Capacitor Replacement Guide
- Amstrad PCW 8512 · Amstrad PCW 9512 · Amstrad PCW 9256 · Amstrad PCW 10
- Floppy Drive Repair · CRT Discharge Procedure
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 Amstrad, PCW 8256/8512 Personal Computer Word Processor Service Manual. Hosted as File:Amstrad PCW 8000 Series Service Manual.pdf, described at Amstrad PCW 8256 / PCW 8512 Service Manual. Specification p. 2; notes to service engineers p. 3; monitor alignment chart p. 17; cabinet parts list p. 23 (PDF p. 24); electrical parts lists pp. 33–34 (PDF pp. 34–35); memory options table on the first chassis schematic sheet (PDF p. 36).
- ↑ 2.0 2.1 2.2 2.3 2.4 Wikipedia, "Amstrad PCW" (revision 1361595210). Retrieved 2026-10-02. UK launch in September 1985 at £399 plus VAT, sold at first through Dixons; the "Joyce" project name; the Schneider Joyce; the PCW 8512 a few months later; the 4 MHz Z80A; the US price of $799.
- ↑ John Donaldson, "Benchtest: Amstrad PCW9512", Personal Computer World, October 1987, pp. 98–102. Scan at archive.org. Retrieved 2026-10-02. The 9512 as a revamp of the 8256 and 8512, its new casing, paper-white screen, keyboard and daisywheel printer.
- ↑ 4.0 4.1 4.2 4.3 4.4 John Elliott, PCW Hardware. Hosted as File:PCW Hardware Reference (John Elliott).pdf, described at Amstrad PCW Hardware Reference (John Elliott). Section 2 (boot process), section 3 (RAM in 16K blocks), section 4 (720 × 256 screen), section 8.2–8.3 (drive support and the controller probe), section 10.2 (keyboard links LK1–LK3).
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Amstrad, The PCW8256 and PCW8512 User Guide and Guide to Locomotive Software's LocoScript (AMSOFT, 1985). Hosted as File:Amstrad PCW8256 PCW8512 User Guide (1985).pdf, described at Amstrad PCW 8256 / PCW 8512 User Guide. Chapter 1, pp. 1–8 (mains plug and 5 A fuse, connecting the keyboard and printer, switching on, brightness thumbwheel, cleaning); Appendix I, pp. 141–143 (troubleshooting); Appendix II, pp. 145–148 (printer loading and maintenance).
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Richard Lloyd, PCW article ("Fifty two years and counting"), Amstrad CPC User Club Magazine (ACUC) issue 1, June 2022. Scan at archive.org. Retrieved 2026-10-02. Community advice: boot behaviour without a disc, the rear connectors, the perished drive belt as the most common fault and its symptoms, cleaning old rubber off the pulley, drive removal from its cage, interchangeable 8256 and 8512 keyboards, converting an 8256 to an 8512, the non-standard drive power cable when fitting a Gotek, acclimatising a machine stored in a loft.