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…
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…
Hi! This is Alice. I’ll be helping out with some of the engineering work at BMOW. Version 0.3.6 for the ADB-USB Wombat is now available. The Wombat is a bidirectional ADB-to-USB and USB-to-ADB converter for keyboards and mice. Connect modern…
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…
This glitching investigation has taken a turn down a strange path. Although the Yellowstone board seems to be working, I wanted to further reduce the nasty-looking signal spikes seen on the oscilloscope. Series resistors on the data bus seem like…
All these Yellowstone glitching mysteries may finally be headed for a conclusion. It looks like there are at least two separate problems with different causes: one causing glitching during a bus cycle and the other causing glitching at the end…
Page 15 of 87
