A Lisa Inside An FPGA

[AlexTheCat123]

Okay, things are updated to fix the Twiggy MT/PWM bug, so anyone with Twiggy drives should be able to update their boards and have both the upper and lower drives work (or at least attempt to work).

It looks like reading is working, but not writing. As writing could be a problem with my drive, someone else should confirm.

That's really strange. Can someone else test and confirm with their Twiggy drives so we can confirm that this isn't just an isolated issue with @sigma7's Twiggies?

However, using a real Sony SS 400k drive OA-D34V (actually original to my Lisa 2), there are numerous misbehaviours, ranging from often not recognizing a disk is in place, not making any progress formatting when it finally does, not being able to read, thinking it has ejected when it hasn't. I tested the drive In a Real Lisa (IRL) and it is fine, failing with the LisaFPGA before and after the successful test IRL.

I just tested with one of my 400K drives (also pulled straight out of a Lisa) and things work just fine. I can read, write, and format without issue. I do recall having some issues similar to yours when using a particular cable. When I use the cable that came with my Floppy Emu (I use it a lot because it's really long), things work fine, but I believe that when I used the cable that went between an 800K drive and the Lite Adapter on one of my Lisas, I had symptoms that were really similar to yours. I'm not exactly sure what the difference is between the two cables, but there's a note on top of that 800K drive that says "this drive MUST be used with the cable that was included with the drive", so clearly there is some kind of difference. Perhaps try a different cable?

IIRC the old 400k OA-D34V required a PWM signal on pin 20 to set the motor speed. The later slimline drives ignored pin 20 and derived the motor speed internally from the head position.

I'm already generating the PWM signal, and things work with my real 400K drive, so this shouldn't be a problem.