Category Yellowstone

An FPGA-based disk controller card for the Apple II family.

Apple II Instant Pascal book

Apple II Pascal Booting Problems

Thanks to beta tester Bryan V., I’ve discovered that Apple II Pascal disks don’t boot normally with the prototype Yellowstone disk controller card. This includes the Pascal master disk as well as other disks built on Pascal, including Fortran, “Apple…

Yellowstone tester wiring

Yellowstone Tester Update

For the past couple of weeks I’ve been developing an automated tester for Yellowstone. My goal is to streamline the program and test process for Yellowstone beta cards, and eventually for the first production run. The ugly tangle of wires…

Short circuit current test on a breadboard

Short Circuit Current Experiments

A couple of weeks ago I shared some thoughts about an automated tester for Yellowstone boards, including how to test for short circuits. One of the questions that grew out of the resulting discussion was whether short circuits could only…

stack of disk drives

Yellowstone: Ready for Takeoff

After several days of extensive testing with the latest Yellowstone prototype, and several years of development work on this universal Apple II disk controller concept, I’m here to say that Yellowstone v2.2 is looking good. Looking very good. It’s the…

Yellowstone front view

Yellowstone 2.2 First Look

Yellowstone version 2.2 is up and running! If you don’t remember what’s changed in v2.2, well… that makes two of us. Luckily we can both go read this August 20 post for a reminder. Hand assembly took about two hours,…

Testing For Short Circuits

I’m still working on the design for an automated Yellowstone tester. The general idea is to use an STM32 microcontroller that’s connected to all the Yellowstone board’s I/O signals, then drive the inputs in various combinations and verify the outputs.…

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