Veteran Microsoft engineer makes his own RAM from scratch using AI
Expensive memory forces former Microsoft engineer to make his own — Dave Plummer makes PDP-11 RAM from scratch
Dave Plummer, a former Microsoft engineer known for his work on Task Manager and Windows Pinball, has embarked on an intriguing project. He aimed to create a new RAM board for his vintage PDP-11 computer, which was released in 1970 and could accommodate up to four megabytes of memory. Plummer turned to ChatGPT and the EasyEDA online circuit simulator for assistance.
After designing the RAM as a standalone card and testing it alongside another board containing the system's M8190 CPU, he added a Lattice MachXO2 FPGA memory controller, four ISSI 1 MB memory chips, a U2S I/O chip, and a bank of DIP switches. However, the project was not without challenges. Plummer had to grapple with the PDP-11's memory bus design, which could only access entire words (two bytes) at once, and the unique memory address bit that acted as a lane selector.
After some trial and error, including never having flashed a FPGA chip before, Plummer managed to overcome these obstacles. Although there are no more updates, it seems he implemented a simple fix in his FPGA code. Some suggested an alternative approach of implementing the memory in software via a Raspberry Pi connected directly to the PDP bus, but Plummer had already explored this option with a modern QBone DEC interface board.
Written by urgent.news from Tom's Hardware's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
