After I assembled and tested the first revision Pi1541io board, I sent the remainder of the prototype batch on to interested members of Forum64 for further testing.
While I’m still hoping for feedback from their side, I’m already working on the next revision of the PCB that will fix a couple of minor issues. As hinted earlier, my intention was to also add optional support for a TXS0108 based level converter. So I acquired one of those modules, tried it on my Pi1541, and couldn’t get it to work at all. It turns out that the TXS0108 is too slow for this job as it seems.
Meanwhile, Steve White has updated his site again, providing an additional wiring diagram. This alternative circuit features an additional 7406 inverter IC that is used for driving the output signals from the Raspberry Pi to the serial bus. Using this solution, multiple devices on the bus should no longer be a problem.
Preview of the current design for revision 2.
So, I ditched the TXS0108 and I am working to support Steve’s 7406 based solution in revision 2 of the Pi1541io. This support will be optional, i.e. you will still be able to use the board with just the level shifter. Speaking of the level shifter: also in revision 2, you may now chose between using a ready made module like in revision 1 or using discrete components instead.
Also, I am still preparing the project repository for upload to Github. Should happen soon now, stay tuned.
Update 2018-05-25: Now that revision 1 is confirmed to be working despite a couple of minor issues, here’s the rev.1 Gerber files for download. Bear in mind though that the improved 2nd revision is under development and will be available soon!
Two weeks ago, there were exciting retro-news on the Lemon64 board: Gorack – aka. Steve White – released the first version of his Pi1541 that he had been working on for quite some time. “Pi1541 is a real-time, cycle exact, Commodore 1541 disk drive emulator that can run on a Raspberry Pi 3B (or 3B+).”
I was curious and wanted to give this a try, but I also wanted proper wiring. So I created my own version of an extension board for the Raspberry Pi. (Not a proper “HAT”, that would require an eeprom and other things.) I then ordered a small prototype batch because others were eager to try our new retro toy, too.
I received the PCBs on Friday after some unfortunate delay at the German customs and by now the first board is assembled and seems to be working fine!
There are two minor issues in revision 1 that I will address in revision 2: Continue reading