Sinclair Amstrad APC 386SX

Resources

• Wiki

There are very few online resources about this PC. It is a rebranded Amstrad 3386. It is famous for a proprietary design of the keyboard, which can’t be replaced with anything commonly available. Without a keyboard, the PC will not boot

Documents

Internals

Motherboard

The CMOS battery is integrated into Dallas DS1287 real time clock controller chip. The integrated battery can be replaced with an external one, following these instructions.

Option	Jumper
Mouse IRQ on 5,4,9,3	LK9-LK12
RAM size	LK19-LK22 (see memory section below)
RAM speed	LK23-LK24 (see memory section below)
Enable onboard HD controlled	LK27
Enable onboard VGA	LK28
Enable onboard mouse interface	LK30
Enable onboard parallel printer port (LPT1)	LK31
Enable onboard floppy disk controller	LK32
Enable onboard serial interface (COM1)	LK33
Enable Power On Self Test (POST)	LK34
Enable expansion bus cache	LK36

CPU Card

Memory

Memory can be expanded by installing different size SIMM modules.

RAM size	SIMMs	LK22	LK21	LK20	LK19
1MB	4 x 256kB	IN	IN	OUT	OUT
2MB	2 x 1MB + 2 x empty	IN	OUT	OUT	IN
2.5MB	2 x 256kB + 2 x 1MB	OUT	IN	IN	IN
4MB	4 x 1MB	OUT	IN	IN	OUT
8MB	2 x 4MB + 2 x empty	OUT	IN	OUT	OUT
16MB	4 x 4MB	OUT	OUT	OUT	OUT

RAM Speed	LK23	LK24
80nS	OUT	OUT
100nS	IN	OUT
120nS	OUT	IN
150nS	IN	IN

ISA Interposer Card

Power Supply

Amstrad SMP-145CB

Keyboard

This is not the keyboard that originally came with this PC. It is an Amstrad PC2386 keyboard, which is compatible with 3386 systems. Please check out the Amstrad 2386 Keyboard page where the keyboard is described in details, including the communication protocol it uses.

Hard Disk Drive

45 MB Seagate ST-157A-1. The correct parameters for this drive are provided on this page.

Floppy Disk Drive

Accessory

Reassembly