Off to the Fab!

The Yellowstone 2.0 disk controller PCB has been sent to the fab. Now we wait. It took longer than I planned to finish it, first because I wasted a couple of days trying to shrink the board by 7 mm,…

Yellowstone 2.0 PCB layout

Yellowstone 2.0 Layout and Route

It took longer than expected, but the PCB layout is finished for version 2.0 of the Yellowstone disk controller. Phew! There’s still a bit of cleanup work to be done before I send the board for manufacturing. Hopefully I can…

Yellowstone Reprogramming and Testing

I’m working on the hardware design for version 2.0 of Yellowstone, my FPGA-based universal Apple II disk controller. Most of it is going well, but I’m facing two major challenges I’m unsure how to solve: how to support user reprogramming,…

Laser 128 Series Universal Disk Controller box

Fixing Laser’s Bugs

Last week I wrote about some test results from Yellowstone, my FPGA-based universal Apple II disk controller based on the Laser UDC design. I described two especially worrisome problems: one with 5.25 inch disks on an Apple IIGS at “fast”…

JTAG signal routing on the Yellowstone PCB

Testing Yellowstone

Work continues on Yellowstone, my FPGA-based universal Apple II disk controller based on the UDC design. I’ve finished some initial testing, and while the results were mostly positive, a few problems may spell trouble. First the good news: I’ve tested…

Yellowstone 3.5 Inch Drive Support!

Success! My Yellowstone disk controller card for the Apple II now works with 3.5 inch floppy drives! Along with the previously-implemented 5.25 inch floppy and Smartport HD support, this completes the triumvirate of Apple II disk drives. While it’s still…

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