I'm working on an Apple III.
When I boot the machine with a disk in the drive, it spins and clacks, and then comes up with the "RETRY" message.
I'm using disks that boot my other Apple III, so I believe the media is OK.
Since the clacking seemed louder than normal, I took another drive mechanism (from an external disk III) and set it in the case, and tried to boot from it, and got the same result - though the disk-in-use light didn't light.
What's new to me - or at least I don't remember seeing it before - is the cursor under the RETRY message has a letter in it. I've seen "B", "F", and "V". This happens with both drives.
I've looked through the III service and diagnostic manuals I can find on-line and don't see any mention of these letters as a diagnostic tool. Does anyone know if these letters are significant, or could they just be artifacts of whatever the real problem might be?
Since both drives act the same way, I'm guessing the issue lies somewhere else, like on the MB, bad cable, etc. I need to do further troubleshooting, but thought I'd lay this out there in case it jogged any memories from someone.