The Universal Chip Analyzer was not called the Universal CPU Analyzer for a reason: from the very beginning of the project back in 2017, I have in mind a tester for various ICs and not just CPUs. The 8087 was the first non-CPU that could be tested on the UCA, but a FPU is technically close to CPU. Another component that often fail on early 70s & 80s computers is the memory (“RAM”) chips. Back in these days, DRAM didn’t come in SIMM or DIMM modules like in the 90s and later, but simply as individual ICs asse
There is a LOT of different DRAM chips from that era, so I had to build an almost universal DRAM shield, able to supply all the common voltages (+5V, -5V and +12V). I choose a universal DIP20 ZIF socket that should cover almost all the 1-bit and 4-bit wide DRAM used in these computers. Unfortunately, an almost infinite variety of pinout existed back then. The easiest solution to route the correct signals to their appropriate pins was to add dedicated “Setup cards”, one for each different pinout. PCBs are ch
The test routine run by the FPGA includes checking for stuck 0s, stuck 1s and adjacent bits flipping correctly from 0 to 1 and from 1 to 0. I have also added more advanced tests (thanks to the years spent on Memtest86+) like memory retention between refreshes, which can degrade over time. The firmware can detect any errors and report the memory address that failed. It can also detect if the DRAM chip supports advanced features like paging (subsequent column access without toggling RAS) and the obscure nibbl