Roland D-20 (apple format) #990
Description
I have been looking at previous responses to the Roland D-20 format, and seeing as I have one in the shop for repair, I have hooked up a GOTEK with flashfloppy (apple format firmware installed).
My initial observations are that apart from some minor issues with disk insertion etc, one of the stepper motor lines has an issue. I scoped out the connections, and with an Artery processor based board, the signal for phase on pin 20 of the gotek seems to have a software pull up enabled somewhere.
When the D20 is trying to step the inputs, they are all correct apart from the input to pin 20 (PA1). The input to pin 20 cycles between +5v and +3.3v rather than +5v and 0v as the other phase pins do.
The D20 sends an active +5v or 0v signal, but the only pin that misbehaves is pin 20 (PA1). If we could find out what is happening here, I stand a chance of scoping out the interface, and making some progress on connecting Roland equipment from the late 80's.
I have not had chance to progress any further as the D-20 rejects the GOTEK after a couple of minutes, presumably as the stepper motor signals are not going below the threshold for a low state to be accepted on the one pin.
Any help or assistance would be welcome, as I know there are people out there with this era equipment with broken disk drives.
BTW I have repaired the original drive and can scope the signals if required. It is all working with an original disk.