Paul Flo Williams
It’s taken three weeks of effort to write emulators for the 8051 microcontroller, ER5911 SEEPROM, SCC2681 DUART and get frustrated over the timings required to make the firmware happy, but my #VT320 emulator now runs the original ROM far enough to pass POST. At this rate, I’ll have understood and annotated the rest of the code by its 40th birthday, and not a minute before. 😓 #retrocomputing
Mar 4 at 11:12pmWeb
Show threadPaul Flo WilliamsMar 10
Now I can send key presses into the #VT320 emulation, I can explore set-up mode and save configurations to the nvram. This morning the terminal kept saying ‘NVR Error’ when I did that. Hmm, close examination revealed that I’d typo'd my implementation of the ER5911 SEEPROM and I’d swapped the opcodes for ‘Program Disable’ and ‘Erase All’ so I was not only erasing everything that’d just been saved, it took 20 ms to do that, when the nvram should’ve been ready immediately. Hurrah. #retrocomputing