An FPGA-based disk controller card for the Apple II family.
Recently I bought an external 800K Macintosh floppy drive, model M0131, so I could confirm its compatibility with my Yellowstone disk controller card for Apple II computers. The testing didn’t go as planned, and now the drive is dead, but…
While I await the new Yellowstone v2.1 PCBs, I’ve been spending more time on testing. With my hacked-up v2.0 PCB, most things are working pretty well, especially with DOS3.3, ProDOS, or game disks. I can connect any odd combination of…
Throughout Yellowstone’s development, I’ve struggled on and off with mysterious problems related to the JTAG programmer. When the programmer is connected to the Yellowstone card, and I turn the computer off and on again, strange things sometimes happen. The Apple…
July 21, 2017 – I began the first work on what would become Yellowstone, with some attempts at designing a Verilog model of Apple’s IWM chip. Four years have passed since then, and I’m still working on this project! Today…
I’m working on what I hope will be the final hardware changes for the Yellowstone 2.1 PCB. Among these are changes to my capacitor usage and placement strategy. In my previous posts I discussed intermittent problems that looked to be…
I’ve been searching for a simple and reliable way to prevent a short-circuit on Yellowstone’s -12V supply when a particular type of Macintosh disk drive is connected. Connecting this drive results in a +5V to -12V short circuit, but if…
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