Editing Amstrad ALT-386SX

{{Infobox computer
| name         = Amstrad ALT-386SX
| image        = [[File:Amstrad ALT-386SX.png|260px|frameless]]
| caption      = ALT-386SX running (photo: MrCauldron, CC BY 3.0)
| manufacturer = Amstrad plc
| type         = Laptop
| release date = 1990
| price        = £2,299
| cpu          = Intel 80386SX at 16&nbsp;MHz, switchable to 8&nbsp;MHz
| memory       = 1 MB, upgradable to 2 MB or 4 MB
| storage      = 40 MB hard disk; 1.44 MB 3.5-inch floppy drive
| display      = Backlit 640 × 480 LCD, 32 grey levels
| graphics     = Cirrus Logic CL-GD610 / CL-GD620 VGA
| input        = 85-key keyboard
| power        = Internal 110–240&nbsp;V AC supply; 12&nbsp;V 2400&nbsp;mAh NiCd battery pack
| dimensions   = 318 × 380 × 95&nbsp;mm
| weight       = 7.0&nbsp;kg with battery
| os           = MS-DOS 3.30
| model        = ALT386SX
}}
<templatestyles src="Template:StyledTable/styles.css" />
The '''Amstrad ALT-386SX''' is a mains and battery portable PC that Amstrad sold from 1990, with an Intel 80386SX at 16&nbsp;MHz, a backlit 640 × 480 VGA LCD, a hard disk and a removable NiCd battery pack. It shares its case, power supply, display, VGA board, keyboard and battery with the [[Amstrad ALT-286]], which has an 80286 on a different main board; one Amstrad service manual covers both.<ref name="smalt">Amstrad plc, ''ALT286 / ALT386SX Laptop Computer V.FTZ Service Manual''. Described at [[Amstrad ALT-286 / ALT-386SX Service Manual]]. Technical specification and safety tests p. 2; electrical parts lists pp. 10–11; cabinet parts list p. 12; ALT386SX main PCB pp. 16–17; ALT386SX schematics pp. 24–26.</ref> ''New Computer Express'' reviewed it in 1990 at £2,299, describing it as Amstrad's second attempt at a portable PC after the PPC range.<ref name="nce92">Keith Pomfret, "Heavy weight lightweight", ''New Computer Express'' no. 92 (1990). Transcribed at [https://cpcrulez.fr/hardware-pc-AMSTRAD_PC-alt-386sx.htm CPCrulez]. Retrieved 2026-10-01. Price, the Conner 40 MB disk, the Epson screen, battery life and charging, weight, expansion card size and the VLSI chips.</ref>

== Specifications ==

{| class="wikitable styled-table" style="width:70%; text-align:left;"
|+'''ALT386SX (service manual, p. 2)'''
! Item !! Value
|-
| Processor || 80386SX, 16&nbsp;MHz switchable to 8&nbsp;MHz; maths co-processor socket
|-
| Wait states || 0.6 (0 with 60&nbsp;ns DRAM)
|-
| RAM || 1 MB (2 MB and 4 MB upgrades)
|-
| Expansion || One 16-bit half-length slot
|-
| Hard disk || 40 MB voice-coil, 25&nbsp;ms access
|-
| Floppy || 3.5-inch 1.44 MB; connector for an external 3.5-inch or 5.25-inch drive
|-
| Display || Backlit LCD, 223 × 169&nbsp;mm, 640 × 480, 32 grey scales in 256-colour VGA mode
|-
| Ports || 25-pin parallel, two 9-pin serial, VGA monitor, AT keyboard
|-
| Power || Internal 110/220/240&nbsp;V AC self-switching supply; removable NiCd pack, two hours' use, two-hour quick charge
|-
| Size, weight || 318 × 380 × 95&nbsp;mm; 7.00&nbsp;kg with the battery, 6.00&nbsp;kg without
|}

The review measured 165 minutes from the battery with little disk access, and found the expansion slot takes a card of up to 155 × 156&nbsp;mm.<ref name="nce92" />

== Hardware ==

The main board (PCB1, part 270673FTZ) carries the NG80386SX-16 CPU (U101) and a VLSI chip set: VL82C201, VL82C202 (memory controller), VL82C203, VL82C204, VL82C205A and VL82C100, with two PAL16R8 PALs (U107, U108), the MC146818AF real-time clock (U126), a DP8473V floppy controller (U125), an M5L8042 single-chip microcontroller (U124) and the BIOS in two TMS27C256 EPROMs (U302, U303).<ref name="smalt" /> The memory and co-processor board is PCB2 (270650FTZ). The VGA board (PCB4, 270563) is common to both models and uses Cirrus Logic CL-GD620 and CL-GD610 controllers with an IMSG176 colour palette and an M5M27C512 EPROM (U508).<ref name="smalt" />

A restoration write-up on oldcrap.org records the parts in one machine: a Rubycon RPS-07 power supply, a Sony SRD3080C-50 80 MB hard disk (BIOS type 24), a TEAC FD-235HF floppy drive and an Epson EG9005-F-LS-2 LCD, with a Phoenix BIOS whose setup is entered with F2 during boot or Ctrl-Alt-S at the DOS prompt.<ref name="oldcrap">Pawel Pieczul, [https://oldcrap.org/2020/08/24/amstrad-alt-386sx/ "Amstrad ALT-386SX"], oldcrap.org, 24 August 2020, with readers' comments to 2024. Retrieved 2026-10-01. Restoration of one machine: parts fitted, configuration switches, PSU recap, SIMM wiring, battery-leak repair; owners' reports of further faults in the comments.</ref> The review's machine had a 40 MB Conner disk and an Epson screen.<ref name="nce92" />

== Power and battery ==

The supply is inside the case and runs from 110 to 240&nbsp;V AC; Amstrad lists it only as a complete power supply unit (UN-1, part 270492).<ref name="smalt" /> The battery pack is type BAT-1, rated 12&nbsp;V 2400&nbsp;mAh NiCd and labelled for both the ALT386SX and ALT286.<ref name="bnfbat">Bibliothèque nationale de France, Collection Charles Cros no. 1008, ALT-286 photographs 15 and 19 of 26, [https://commons.wikimedia.org/wiki/File:Collection_Charles_Cros._Micro-ordinateurs_(m%C3%A9dia_-_multim%C3%A9dias)._Micro-ordinateurs_Amstrad_-_ALT-286._Micro-ordinateur_Amstrad_ALT-286,_n%C2%B0_de_s%C3%A9rie_N_42016595_-_btv1b550130236_(19_of_26).jpg Wikimedia Commons]. Retrieved 2026-10-01. The BAT-1 battery label and the ALT-286 rating label.</ref> ''New Computer Express'' reported that the pack recharges slowly while the machine runs from the mains and can be "blast" charged in two hours with the machine switched off.<ref name="nce92" /> See the [[Amstrad ALT-386SX Maintenance Guide]] for the pack and the backup battery on the board.

== Known faults ==

The oldcrap.org write-up and its readers' comments describe three recurring problems: leaking electrolytic capacitors in the power supply, which pull the output voltages down; leakage from the backup battery and a surface-mount capacitor on the main board, which corrodes tracks around the memory; and failed original hard disks.<ref name="oldcrap" /> The guides cover each:

* [[Amstrad ALT-386SX Maintenance Guide]] – battery packs, configuration switches, memory, drives, display and fan
* [[Amstrad ALT-386SX Troubleshooting Guide]] – power, display, memory and disk faults
* [[Amstrad ALT-386SX Capacitor Replacement Guide]] – the power supply and main board capacitors

== Documentation ==

* [[Amstrad ALT-286 / ALT-386SX Service Manual]] – specification, board views, parts lists and schematics
* Drivers and utilities recovered from an ALT-386SX, including the display switching tools, are on [https://archive.org/details/alt-386 archive.org]

== Related pages ==

* [[Amstrad ALT-286]]
* [[Amstrad PPC 512 / PPC 640 Service Manual]] – Amstrad's earlier portables
* [[Battery Explosion, Capacitor or Corrosion Damage]] · [[Battery Refurbishment]] · [[Hard Drive Maintenance and Repair]]

== References ==
<references />

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[[Category:Amstrad]]