PC104 bus 80386SX CPU

I bought this because it is in a convenient Eurocard format, and is fully documented with a manual and a circuit diagram.

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  • 25 MHz 80836SX or 50 MHz TI 486SXLC2 processor
  • TI486SXLC2 contains 8 Kbyte of internal cache
  • PC-AT architecture
  • 2 or 4 Mbytes of DRAM
  • 1 or 2 Mbytes of FlashFile™ memory
  • Includes Arcom Flash Filing System
  • Includes ROM-DOS 6.22
  • Optional 128 Kbyte of battery backed SRAM
  • Battery backed Real Time Clock
  • FDD interface via vertical 34-way header
  • HDD IDE interface via vertical 40-way header
  • LPT parallel port via vertical 26-way header
  • COM1 and COM2 RS232 serial ports via individual 9-way D-type plugs
  • Link selectable half- duplex RS-485 available on COM2
  • AT keyboard interface via a 6-way ‘Mini’ DIN socket
  • Mini Buzzer for audible alarm
  • Watchdog timer generating an NMI or optional reset (3 second time-out)
  • PC/104 Interface, 16-bit, single Master only
  • 11 mAHr NiMH battery: Full charge time = 70 hours
  • Hold-up time = 550 hours
  • Battery life = 6 years @ 25°C
  • Operating temperature range :
    +5°C to 65°C (with battery fitted)
    -20°C to +70°C (without battery fitted)
    486 SXLC
    +5°C to 50°C (with battery fitted)
    -20°C to +50°C (without battery fitted)
  • Power Consumption: @ +5V 700 mA
  • MTBF (using generic figures from MIL-HDBK-217F at ground benign): 152,240 hours
  • Single Eurocard form factor
  • EMC Chassis connection point
  • Status LEDs for Flash drive access and Processor running
  • Single User Link

The board was still sealed in the original manufactures anti-static bag. The battery might no longer work although on the board the vendor used there was no sign of corrosion or leakage.

The user guide which includes full schematics.

The board can be used stand alone, the embedded DOS I/O is redirected to one of the UARTS (see screenshots) hence you can upload new programs and execute them without a video/hard disk/floppy connected.

The board can be used on an ISA bus system using a PC104 to ISA adaptor board (this was not included in the sale, alas).

The vendor had 4 of these boards left, 3 new and 1 used (which he will keep).

The board has no video output, so it would need a video card to run Windows. I have not found any on the web yet. It is essentially a headless MSDOS machine, which is quite good enough for many control systems.


Adobe Portable Document Format - 836.38 kB - 05/07/2024 at 21:39



Adobe Portable Document Format - 41.63 kB - 05/07/2024 at 21:39


  • 1 × 80386SX processor
  • 1 × F82C836B-25 Single-Chip 386sx AT logic

  • Components

    Keith05/10/2024 at 21:19 0 comments

    IC 2 M27C1001 labelled AR8000-00135-008-104

    This is an 128K x 8-bit EPROM.

    The data appears very sparse, to say the least.

    00000 to 01fff: all FF
    02000 66 23 80 3f 66 3c 41 3f
    02008 to 1ffff: all zero

    which disassembles to this

    0:  66 23 80 3f 66 3c 41    and    ax,WORD PTR [eax+0x413c663f]
    7:  3f                      aas

     which does not look like useful code.

    I think it is two little-endian 32-bit vectors:


    Underneath the board are two Intel E28F008S5 surface-mounted flash ROM chips. That is 2 Mbytes total enough to store the ROM-based DOS. I will have to read them when I have the board up and running. 

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