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…
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…
I’ve fallen into a deep hole involving current-limiting circuits and current sources, in an attempt to solve a minor problem with the Yellowstone disk controller. In the big scheme of things, this isn’t a very important problem, but it has…
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