The role of Steve will now be played by a small red-faced boy Oops. I’ve verified that the spikes I’m seeing on data signals are largely due to the embarrassingly poor ground connections on my oscilloscope probes, rather than issues…
This glitching investigation has taken a turn down a strange path. Although the Yellowstone board seems to be working, I wanted to further reduce the nasty-looking signal spikes seen on the oscilloscope. Series resistors on the data bus seem like…
All these Yellowstone glitching mysteries may finally be headed for a conclusion. It looks like there are at least two separate problems with different causes: one causing glitching during a bus cycle and the other causing glitching at the end…
Did anybody else see this week’s news about problems with Hubble’s 80s-vintage onboard computer and think: *gasp* My moment in life has arrived! Hold my beer. “Hello, NASA? Did you guys try PR#6? Sometimes the boot disk gets dust on…
Driving 11111111 from RAM through the ‘245 onto the data bus is causing trouble. I can see this clearly – other chips begin to glitch the moment the ‘245 is enabled. But driving 11111111 from the FPGA through the ‘245…
All the clues surrounding Yellowstone’s glitching problems seem to point towards a power supply problem with the ‘245 bus driver and/or the SRAM. The good news is that I now have a “solution” that seems to fix the glitches, and…
I’ve discovered something very useful about the signal glitching problem with Yellowstone: I can reproduce the problem (or a form of it) without booting a disk, and even without any disk drive attached. After many hours, I think I’ve narrowed…
This Yellowstone glitching problem has gone from puzzling to frustrating to potentially project-ending. I’m still not exactly sure what’s going wrong, let alone how to fix it, and I’ve nearly exhausted all my troubleshooting ideas. In the hopes that maybe…
I’m still chasing the cause of a rare Q3 clock glitch on the Yellowstone board. I’ve collected some more data that may help point to the underlying cause. It’s quite a puzzle, but I like a good mystery. I began…
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