Usagi’s New Computer is a Gas!
[Dave] over at Usagi Electric has a mystery on his hands in the form of a computer. He picked up a Motorola 68000 based machine at a local swap meet. A few boards, a backplane, and a power supply. The only information provided is the machines original purpose: gas station pump control.
The computer in question is an embedded system. It uses a VME backplane, and all the cards are of the 3u variaety. The 68k and associated support chips are on one card. Memory is on another. A third card contains four serial ports. The software lives across three different EPROM chips. Time for a bit of reverse engineering!
[Dave] quickly dumped the ROMs and looked for strings. Since the 68k is a big endian machine, some byte swapping was required to get things human readable. Once byte swapped, huge tables of human readable strings revealed themselves, including an OS version. The computer runs pSOS, an older 68k based real time operating system – exactly what one would expect a machine from the 80’s to run.
The next step was to give it some power and see if the gas station computer would pump once again. The LEDs lit up, and a repeating signal showed up from one of the serial ports. The serial connections on this machine are RS-485. Not common for home computers, but used quite a bit in industrial embedded systems. Unfortunately, the machine wouldn’t respond to commands sent from a terminal. The communication protocol remained a mystery.
Since this video has gone up though, several people have provided a wealth of information at the vintage-micros channel over on [Dave’s] Usagi Electric Discord.
Gas pumps are a bit of a departure from [Dave’s] usual minicomputer work. We’re no strangers to embedded systems here though.
youtube.com/embed/i0Qw8GrOcp0?…
hackaday.com/2026/02/02/usagis…
