RetroTechCollection

Amstrad PC7386SX

The Amstrad PC7386SX is a desktop IBM-compatible PC built around a 25 MHz Intel 80386SX, sold by Amstrad from 1992 as the 386 model of its PC7000 range. It came with a 40 MB or 80 MB hard disc, a 3.5-inch 1.44 MB floppy drive, Super VGA graphics on the main board, two ISA slots and a PS/2-style keyboard and mouse, with MS-DOS 5.0, the Amstrad Desktop menu and Lotus Works 3.0 pre-loaded.[1] The same main board, power supply and case form the PC side of the Amstrad Mega PC.[2]

Amstrad PC7386SX
PC7386SX with monitor, keyboard and mouse, from the cover of Amstrad's service manual
Specifications
ManufacturerAmstrad plc
TypeDesktop personal computer
Released1992
CPUIntel 80386SX at 25 MHz
Memory1 MB (40 MB model) or 2 MB (80 MB model), up to 16 MB in 30-pin SIMMs
Storage40 MB or 80 MB IDE hard disc; 3.5-inch 1.44 MB floppy drive
Display—
SoundInternal speaker with volume control
GraphicsWestern Digital WD90C11 VGA, 256 KB (512 KB option), up to 1024 × 768
Ports / interfaceBidirectional parallel, two RS-232C serial, PS/2 keyboard and mouse, VGA, monitor power socket
ExpansionTwo 16-bit ISA slots (2/3 length) on a riser
Power50 W, 110/220–240 V auto-switching
Dimensions325 × 78 × 281 mm (W × H × D)
OS / FirmwareMS-DOS 5.0 with Amstrad Desktop

History

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Amstrad advertised the PC7000 series in PC Review in November 1992 as "the advanced PC for beginners". The advert gives the PC7286 a 16 MHz 286, 1 MB of RAM, a 40 MB hard disc and VGA graphics, and the PC7386SX a 25 MHz 386SX, 1 MB or 2 MB of RAM, a 40 MB or 80 MB hard disc and Super VGA at up to 1024 × 768. Both models had a 1.44 MB floppy drive, a keyboard and mouse, MS-DOS 5.0, the Amstrad Desktop graphical front end with an on-screen tutorial, and Lotus Works 3.0, all pre-loaded, with a 12-month call-out warranty. The advert states that its prices were correct at 1 September 1992.[3] Amstrad's service manual for the machine is dated October 1992.[1] By mid-1993 dealers were selling a PC7386SX Family Pack with 2 MB of RAM.[4] Wikipedia lists the PC7286, PC7386SX and PC7486SLC as the PC7000 series.[5]

Hardware

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The main board is silkscreened Amstrad VSC386SXD V.2.01. Amstrad sold it as main PCB assembly 273894, supplied without SIMMs or CPU.[1] The chipset is Western Digital's: a WD76C10 system controller, a WD76C20 floppy, IDE and real-time clock controller, and a WD76C30 serial, parallel and interrupt controller.[1]

Main board ICs (electrical parts list, p. 19)
Ref Part Amstrad part no.
U13 80386SX-25 CPU, flat pack 273932
U15 WD76C10 ver. F 273883
U33 WD76C20 ver. E 273884
U17 WD76C30 ver. D 273885
U50 90C11 VGA controller (printed "ED90C11") 273886
U51, U52 44256-8 video DRAM 273937
U57 ADV471-66 RAMDAC 273939
U55 ICS1394M-030 clock synthesiser 273938
U32 8042 keyboard and mouse controller 273935
U18, U19 27C512-150 BIOS ROM, low and high 273933
U38, U39 / U40–U42 MC1488A / MC1489A serial line drivers and receivers 272286 / 272287

The parts list describes U32 as an "8042 Quad Op Amp"; the top view labels it as the keyboard and mouse controller. The top view and schematic 3/13 also show a coprocessor position for an 80387SX at U14, which the parts list does not include.[1]

The crystals are a 50.00 MHz oscillator (OSC1), 48.00 MHz (OSC2), 42.00 MHz (OSC3), a 32.768 kHz clock crystal (X1) and 14.318 MHz (X2).[1]

Memory

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Main board VSC386SXD V.2.01, from the service manual's top view. The SIMM banks are the long sockets at lower left.

Amstrad specifies 1 MB on the 40 MB model and 2 MB on the 80 MB model, expandable to 16 MB "via 4 SIMM sockets". The top view and schematic 2/13 show eight 30-pin SIMM positions (U2–U9), arranged as four banks (0 to 3) of two sockets marked H and L.[1] In 1993 a memory dealer sold the same 2 MB and 4 MB upgrade kits for the PC7286 and the PC7386SX.[4]

Video

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The VGA controller supports VGA, EGA, CGA, MDA and Hercules modes, with 256 KB of video memory as standard and a maximum resolution of 1024 × 768 in up to 256 colours.[1] Schematic 12/13 draws two 44256 video RAMs at U51 and U52 and two more at U53 and U54 inside a box marked "512K option".[1] The top-view drawing labels the four video RAM positions "4464-80" and marks the area "VGA memory expansion"; the parts list gives 44256-8 for U51 and U52, so read the part on your own board before buying chips for the upgrade.[1]

Drives

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The drive bracket holds a 3.5-inch third-height floppy drive and a 3.5-inch half-height hard disc.[1] The parts list gives a Sony MP-F17W-10 floppy drive, a Seagate ST351 (AX) for the 40 MB model and a Sony 80 MB drive for the 80 MB model; the specification quotes access times of 28 ms and 19 ms.[1] The floppy and IDE interfaces are on the main board, from the WD76C20.[1]

Case, power and front panel

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The supply is a 50 W auto-switching module (273888) at the rear right of the case, connected to the main board through a 12-pin header, CON1.[1] The rear panel carries a volume control (knob A-4 on a 500 Ω potentiometer, DE-9) for the internal speaker (DE-10), which is the machine's only sound output.[1] The front panel connector carries reset, the hard disc lamp, the speaker, the turbo lamp and switch, the power lamp and the keylock; Amstrad's schematic gives the power lamp as green, the hard disc lamp as red and the turbo lamp as yellow.[1]

Monitors

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Amstrad's specification offers three 14-inch monitors with the PC7386SX: the PC14FMD flat-screen paper-white monochrome VGA monitor, the PC14M39 colour monitor with a 0.39 mm dot pitch and the PC14M28 colour monitor with a 0.28 mm dot pitch.[1] The system unit has a power socket for the monitor.[1] The PC7386SX service manual does not cover any of these monitors.

Relation to the Mega PC

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The Amstrad Mega PC adds a Sega Mega Drive card in one of the two ISA slots and a dual-sync monitor, the PC14DSM. Amstrad's Mega PC service manual refers engineers to the PC7386SX manual for the main unit, and the Mega PC parts list uses the same part numbers for the main PCB (273894) and the power supply (273888).[6] Repair notes for the main board apply to both machines.

Repair guides

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Documentation

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References

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  1. ↑ 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 1.17 Amstrad plc, PC7386SX Personal Colour Computer Service Manual, first published October 1992. Hosted as File:Amstrad PC7386SX Service Manual.pdf, described at Amstrad PC7386SX Service Manual. Technical specification p. 2; main PCB top view p. 3; schematic diagrams 1/13–13/13 pp. 5–17; cabinet exploded view p. 18; cabinet and electrical parts lists p. 19.
  2. ↑ Amstrad plc, MegaPC user instructions (multilingual), 1992, English introduction: "This PC is based on the Amstrad PC7386SX computer". Scan at archive.org/details/amstrad-megapc. Retrieved 2026-10-02.
  3. ↑ Amstrad plc, advertisement "The advanced PC for beginners", PC Review issue 13, November 1992, p. 22. Scan at archive.org/details/pc-review-13. Retrieved 2026-10-02. PC 7286 and PC 7386SX specifications, pre-loaded software, warranty, RRPs correct at 1/9/92.
  4. ↑ 4.0 4.1 Practical PC vol. 2 issue 6, June 1993, dealer advertisements: "PC7386SX Family Pack" with a 25 MHz 386SX and 2 MB RAM; memory upgrade kits for the "PC7286, 7386" in 2 MB and 4 MB sizes. Scan at archive.org. Retrieved 2026-10-02.
  5. ↑ Wikipedia, "Amstrad", section "PC compatibles". Retrieved 2026-10-02. List of PC7000 series models.
  6. ↑ Amstrad plc, MEGAPC3H40 with Games Card / PC14DSM 14" Dual Synch Colour Monitor Service Manual. Hosted as File:Amstrad Mega PC Service Manual.pdf, described at Amstrad Mega PC Service Manual. Note to engineers (PDF p. 3); parts lists (p. 4).


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