the crash occurred in an Apple IIe and an Apple IIgs.

the crash occurred even when no disk drives were attached вЂ“ so itвЂ™s unrelated to the drive or the disk contents.

it didnвЂ™t matter what slots the cards were in.

it didnвЂ™t matter what the other cards were.

With more investigation, I gathered these clues:

With another card present, the computer would crash into the system monitor during power-up about 90% of the time. Success! But the excitement was short-lived: it only worked when Yellowstone was the only card installed in the Apple IIe. With Yellowstone configured to clone a Liron disk controller, I was able to boot from a Unidisk 3.5 drive as well as from a Floppy Emu in Smartport emulation mode. This story begins 12 days ago, the first time I successfully booted my Apple II using the Yellowstone card. Those nice clean zeroes and ones are gone, and instead IвЂ™m struggling with voltages, logic thresholds, capacitance, and power in an attempt to explain whatвЂ™s going wrong. ThatвЂ™s the story of my Yellowstone FPGA-based disk controller for Apple II, and itвЂ™s slowly driving me crazy. The digital abstraction of zeroes and ones is lovely, but electronics debugging often requires a deeper look into the realm of analog signals.

Bryce on The Demon Razor that WouldnвЂ™t Turn Off.Jane on 3D Printed Floppy Emu Case Experiment.Eric on Floppy Emu Update: Smartport Daisy-Chain Support.ianpolpo on First Look at the RP2040 вЂ“ Raspberry Pi Microcontroller.

Yellowstone Universal Disk Controller for Apple II Floppy Emu Disk Emulator for vintage Apple II, Macintosh, and Lisa

Macspice probe