ISA 16 Bit Card - Front

ISA 16 bit RAM expansion card

PC Boards – RAM expansion board for AT 286 with piggyback chips

ISA 16 Bit Card - Front
ISA 16 Bit Card – Front
Piggyback RAM
Piggyback RAM
ISA 16 Bit Card - Dip Switches
ISA 16 Bit Card – Dip Switches
ISA 16 Bit Card - Code
Code

This is a RAM expansion board with parity check for IBM AT 286 computers and will be mounted in an ISA 16 bit bus. It has two rows of 18 chip slots, each row contains dynamic RAM chips in a 8+1 setup (8 chips for storing data plus 1 chip for parity check). The memory capacity of the board is doubled by mounting the memory chips in couples, the two chips are soldered one on the other’s top (piggyback).

Two dip switch selectors are used to set the extension RAM configuration.

The memory chips onboard aren’t the common 4164 (64K x 1bit) or 41256 (256K x 1bit) series but an uncommon Texas Instrument chip (RTI 8531 / 1501843).

I couldn’t find any information about these memory chips, boards from IBM with a very similar layout make me think this is a fully-loaded 512KB board. Possibly each memory chip is a 64K x 1 (64Kbit).

Productor: IBM or compatible
Year: mid ’80s
PCB text: PARITY MEM. CARD, W03019142, 1501518 1463 7777, 3585