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Amstrad PC3086

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Amstrad PC3086
PC3086 with monitor and keyboard, from Amstrad's 1990 leaflet
Specifications
ManufacturerAmstrad plc
TypeDesktop personal computer (IBM PC/XT compatible)
Released1990
CPUIntel 8086 at 8 MHz
Memory640 KB, parity checked
Storage3.5-inch 720 KB and/or 5.25-inch 360 KB floppy drives; optional 30 MB XT-IDE hard disk
Display—
Sound—
GraphicsBuilt-in Paradise VGA, compatible with EGA, CGA, MDA and Hercules
Ports / interfaceParallel (25-way), RS232 serial (25-way), Amstrad mouse, VGA, monitor power outlet
ExpansionThree full-length and one half-length 8-bit ISA slots
Dimensions425 × 135 × 390 mm (W × H × D)
OS / FirmwareMS-DOS 3.30A
PredecessorAmstrad PC2086

The Amstrad PC3086 is the entry model of Amstrad's "Generation 3" range of IBM-compatible desktop PCs, launched in 1990 alongside the 80286-based Amstrad PC3286 and the 80386SX-based Amstrad PC3386SX. It is an XT-class machine with an 8 MHz 8086, 640 KB of memory, built-in VGA and an XT-type IDE hard disk interface, in a flat metal case shared with the other two models.[1][2][3] Amstrad PC International reported the range as the replacement for the 2000 series, to be shown at OrgaTech '90.[4]

Specifications

PC3086 (Amstrad leaflet and user manual)
Item Value
Processor 8086 at 8 MHz; 8087 co-processor socket
Memory 640 KB, parity checked; further memory only through an 8-bit expanded memory (EMS) card
Floppy drives One or two 3.5-inch 720 KB, or one or two 5.25-inch 360 KB
Hard disk Optional 30 MB IDE, 39 ms, on the built-in XT-type IDE adaptor
Drive bays Two 3.5-inch third-height and two 5.25-inch half-height
Expansion Three full-length and one half-length 8-bit ISA slots; expansion bus at 4 MHz
Video Extended VGA, also supporting MDA, CGA, Hercules, EGA and MCGA
Ports Bi-directional parallel (25-way D), RS232C serial (25-way D), mouse, VGA, monitor power socket
Keyboard 102-key, AT style
Real-time clock Battery-backed NVR, quoted as a 10-year battery
Size 425 × 135 × 390 mm
Software MS-DOS 3.30A

Sources: the leaflet's specification page and the user manual.[2][1][5] Amstrad offered 12-inch paper-white VGA mono, 14-inch medium-resolution VGA colour (0.42 mm dot pitch) and 14-inch high-resolution VGA colour (0.29 mm) monitors.[2]

Hardware

Option links on the PC3086 main board (user manual p. 11-5)

John Elliott describes the PC3086 as a much more conventional PC than Amstrad's earlier XTs: the expansion cards run front to back as on standard XT and AT boards, the three full-length slots are on a riser board, the case is metal, drives sit on rails, and there is no lid over the slots, so the whole cover comes off to fit a card.[6] The graphics are a Paradise VGA chipset on the main board, configured by four DIP switches on the back panel.[6][7][8]

The clock and setup memory are in a CMOS RAM chip with a built-in lithium battery. Amstrad says the whole chip must be replaced when the battery is exhausted; Elliott identifies it as a Dallas DS1287 and has replaced it with a DS12C887.[9][10] The 8086 is soldered to the board, so the NEC V30 swap that Elliott suggests for running Windows 3.0's colour drivers means desoldering it.[11]

The keyboard uses Amstrad's own interface and an 8049 microcontroller, part 40178, which also supports the keylock; it is electrically compatible with the PC2086 keyboard.[12][13] The mouse port is not interrupt-driven and has no IRQ.[14] The hard disk interface is XT-type IDE, so a replacement drive must support XT mode; Elliott notes that a PC3086 drive will not work in a modern PC.[15][13][16]

Amstrad's main board drawing and the option link table are on pp. 11-5 and 11-6 of the user manual; the links disable the built-in COM1, VGA and hard disk adaptor, set changeline for each floppy drive and turn off the power-on self test.[5][17] See the Amstrad PC3086 Maintenance Guide for the full table.

Configuration

The PC3086 has no SETUP program. Display and floppy drive settings are held in the clock chip and changed with the DEVICE command on the system disk; at start-up the BIOS (version 1.2 in the manual's example) reports "AMSTRAD PC3086 640K".[18][19][11] Amstrad GmbH's interrupt table gives IRQ 2 to the real-time clock, IRQ 4 to the serial port, IRQ 5 to the hard disk, IRQ 6 to the floppy controller and IRQ 7 to the printer port, with IRQ 3 free.[14]

Known faults

  • The CMOS RAM battery runs down with age and the BIOS reports "WARNING: CMOS battery failed"; the fix is a new clock chip.[20][10]
  • A replacement hard disk must be an XT-mode IDE drive; otherwise disable the built-in adaptor and fit a separate XT controller.[16][15]

The procedures are in the Amstrad PC3086 Maintenance Guide and the fault tables in the Amstrad PC3086 Troubleshooting Guide. No capacitor list has been published for the PC3086: Amstrad's 53-page service manual for the three Generation 3 models (reference SM-PC3000) survives in the Centre for Computing History's collection but has not been scanned, and the acpc.me archive lists it as missing.[21][22]

Documentation

References

  1. ↑ 1.0 1.1 Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 1-2 to 1-4. Specifications of the three models and memory configuration.
  2. ↑ 2.0 2.1 2.2 Amstrad plc, PC3086 leaflet, © August 1990, p. 2 (specification). Hosted as File:Amstrad PC3086 leaflet (1990).pdf.
  3. ↑ Thomas Kallay, "Big Brother: AMSTRADs Flaggschiff der Generation 3: der PC3386 SX", Amstrad PC International, February/March 1991, pp. 41–42. Internet Archive. Retrieved 2026-10-02. Specification table and test of a PC3386SX with a 100 MB Conner disk.
  4. ↑ "Neue PC-Reihe von Amstrad", Amstrad PC International, October/November 1990, pp. 50–51. Internet Archive. Retrieved 2026-10-02. Announcement at OrgaTech '90 of the PC3086, PC3286 and PC3386 as replacements for the 2000 series, with a specification table.
  5. ↑ 6.0 6.1 John Elliott, "Amstrad XTs: Models", seasip.info, 19 April 2013. Retrieved 2026-10-02. Construction and specification notes on the PC3086 and PC5086.
  6. ↑ John Elliott, "PC3086 DIP switches", seasip.info, 1 November 2003. Retrieved 2026-10-02.
  7. ↑ Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 6-5 to 6-15. PS/2 and AT video modes, disabling the built-in VGA, links 901 and 902, and the video DIP switches.
  8. ↑ Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 13-2 to 13-4. Transporting a hard disk PC, PARK.COM, and replacing the CMOS RAM.
  9. ↑ 10.0 10.1 John Elliott, "PC3086 clock chip replacement", seasip.info, 15 June 2004. Retrieved 2026-10-02. The CMOS battery warning, the DS1287 and its DS12C887 substitute, case removal and chip location.
  10. ↑ 11.0 11.1 John Elliott, "Amstrad XTs: Questions and Answers", seasip.info, 26 June 2019. Retrieved 2026-10-02. Setup utilities (DEVICE.COM on the PC2086 and PC3086, Ctrl-Alt-S on the PC5086) and Windows 3.0 on these machines.
  11. ↑ John Elliott, "102-Key Keyboard", seasip.info, 28 August 2010. Retrieved 2026-10-02. The 8049 keyboard microcontroller, part 40178 in the PC2086 and PC3086.
  12. ↑ 13.0 13.1 John Elliott, "Using Amstrad XT peripherals on other machines", seasip.info. Retrieved 2026-10-02. Monitors, floppy and hard drives, keyboards and mice of the PC3086 and PC5086.
  13. ↑ 14.0 14.1 "AMS-Line: Der Informationsdienst der Firma AMSTRAD", Amstrad PC International (page header CPC), August/September 1991, p. 7. Internet Archive. Retrieved 2026-10-02. Amstrad GmbH's column: the meaning of the start-up dots, the PC4386SX BIOS indicator, and the interrupt and I/O address tables of the PC3086, PC3286 and PC3386SX.
  14. ↑ 15.0 15.1 Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 9-1 to 9-3. Built-in IDE adaptors (XT type on the PC3086, AT type on the PC3286 and PC3386SX) and the hard disk type table.
  15. ↑ 16.0 16.1 John Elliott, "Using normal peripherals on Amstrad XTs", seasip.info. Retrieved 2026-10-02. Floppy cables and drives, hard drives and keyboards for the PC3086 and PC5086.
  16. ↑ John Elliott, "PC3086 option links", seasip.info, 23 January 2004. Retrieved 2026-10-02. Link functions from the user manual and the service manual schematic.
  17. ↑ Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 4-2 to 4-18. The DEVICE command: display, floppy drive, cache, memory map and processor speed settings.
  18. ↑ Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 3-7 to 3-15. Voltage selector, power switch, the "Please wait." self-test dots, start-up messages and BIOS versions, and the SETUP program for the PC3286 and PC3386SX.
  19. ↑ Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 14-1 to 14-3. Non-fatal and fatal hardware error messages.
  20. ↑ Centre for Computing History, "Amstrad PC3086 PC3286 PC3386SX Colour Personal Computers Service Manual" (CH27476): 53-page service manual with schematics and wiring diagrams, reference SM-PC3000. Retrieved 2026-10-02.
  21. ↑ acpc.me (ACME) archive, Amstrad PC section, directory DOCUMENTS_TECHNIQUES/SERVICE_MANUALS. Retrieved 2026-10-02. The PC3086/PC3286/PC3386SX, PC4386SX and PC5086/PC5286 service manuals are listed with placeholder images only, marked missing.


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