An FPGA-based disk controller card for the Apple II family.
I’ve returned to the question of how best to limit the current from Yellowstone’s -12V supply. I discussed this earlier in Yellowstone and Macintosh Floppy Drives and Transistor Puzzles, and had more-or-less settled on the idea of using a current…
I’ve written several times about Yellowstone’s need for in-system FPGA reprogramming. Once the Yellowstone card is in the user’s hands, the user needs a way to update the FPGA firmware when new versions are released, without requiring a JTAG programmer…
The Yellowstone disk controller’s whole reason for existence is its ability to control any type of Apple II disk drive, but for a few Apple II programs, this universality causes problems. Yellowstone handles standard 5.25 inch drives just fine, but…
Testing continues for my Yellowstone disk controller card for Apple II computers. One of the design goals for Yellowstone was to support Macintosh floppy drives, and today I got a Mac drive working for the first time! I transplanted a…
Good news! I’ve completed the stress test involving seven filled peripheral slots to increase the data bus capacitance to its maximum, and Yellowstone is still performing OK. I tried this stress test on both the Apple IIgs and Apple IIe,…
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…
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