Reading old EPROM with Arduino

Hand made Arduino reader for a 1980’s EPROM chip. Chip not shown in photo. Ribbon cables were not readily available, but some electrical tape made the wires manageable. Push button at top right initiates a full chip read with a hex dump to serial output.

My rather interesting new job involves maintaining some 1980’s full-motion flight simulator technology. The Digital Control Loading system for this simulator — the part which controls movement and force feedback of the flight controls — is made up of large TTL circuit cards (a Fokker system).

The mathematical procedures which calculate the feedback, etc., are not done in the main simulator computer, but are done by Channel CPU cards, which each contain an original intel 8086-2 microcontroller. Those microcontrollers run firmware which is burned onto old 32k and 64k EPROM memory chips.

1980’s era Channel CPU card. Performs mathematical functions to calculate positioning and force-feedback for flight simulator controls. Original Intel 8086-2 microcontroller at top left. 32KB and 64KB EPROM chips are the bottom four chips with labels on them.

We don’t have the source code for the math on the EPROMs, so we needed to make backups of the data on them. I was able without too much difficulty to put together a reader for the 32KB chips with an Arduino Mega and a few spare parts. I haven’t done the 64KB reader yet, but I do not think it will be difficult.

Reading these old EPROMs is straightforward: basically just setting address pins to the byte address you want, toggling the OUTPUT ENABLE pin, and then reading the byte from the 8 output pins. I have a button inserted onto the Mega which causes it to begin reading all the bytes on by one and dumping them to the serial output, in an ASCII format (0xHH).

Creating an Arduino programmer (burner) for the EPROM chips will be more challenging, I expect, since programming them requires higher voltage pulses (21V for the 32KB chip). But I should be able to manage that with a relay, I’m thinking.

In summary, it was an interesting and fun project illustrating how Arduino / AVR skills can be used in the work-a-day world.

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