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Amstrad PC3086

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Amstrad PC3086
Amstrad PC3086 (1990 leaflet)
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

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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

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Amstrad PC3086 option links (user manual p. 11-5)
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

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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

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  • 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

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References

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  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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