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.
Is the power lamp at the keyboard lit up ?
In many cases the Apple III refuses normal boot up, if that lamp beneath the keyboard is dead.
If that lamp is dead replace and try if boot sequence then is performed.
If yes - check system with confidence test disk.
The power lamp does light.
Kind of hard to use the Confidence disk since the drive doesn't work I can move that image across using ADT, I guess.
The proposal to use the confidence disk was made assuming that the source of trouble would be the powerlamp
and that the disk would be the next step after solving the boot problem.....
the priority is of course first to get access to the diskdrive....
Did you only try to boot SOS or did you also try for example startup with the AppleII emulation disk ?