Hi there,
I'm a bit lost troubleshooting this quirky machine, and I figured that this would be the best place to discuss with tech wizards.
I got my hands onto a regular Apple III, 128k. Nothing particular with this one.
I had to change a 74S257N for it to boot, and I raised the 128K 5V card to 256k.
However I cannot boot on anything at all, either using the internal drive or an external Disk III plugged in the internal port.
I've cleaned heads, but I keep getting the dreaded "RETRY" prompt.
I'm testing a Confidence disk written from an Apple II (using a Floppy Emu & Copy II Plus 9.1, Auto Bit Copy in Try Standard mode), having none of the original software.
I've noticed that on the internal drive, the belt falls pretty easily from the bottom, although it does not feel stretched nor desintegrating.I have never attempted surgery on a Disk II/III before.
What is the best course of action?
Help is much appreciated.
Disk III is basically Disk II with drive daisy chain support added.
If you have a II and working Disk II lying around, just swap the analog board and test the drive on the II.
That's what I wanted to try in the last recourse, but it did not help. I believe the Disk II is fine though, so I'd be enclined to blame the floppy.
What's the best way to write an Apple III floppy from an Apple II, without ADTPro?
Update : turns out the Confidence floppy I had was invalid for some reason. Tried with System Utilities and it worked.
Although the original Disk III still suffers from something (which I presume is the belt being a bit too loose and the 50/60 disk going AWOL), and the external Disk III requires tampering with the clamp for disks to properly read. Time to investigate...
Assuming the belt on the internal drive is tight enough to actually spin a disk, most of the drives I've seen have a strobe wheel on the bottom side. You can check the disk rotational speed without a running program using a "video tachometer" app on your phone.
My notes are kind of cryptic, but I think this procedure will force the floppies on or off:
Enter the ROM monitor with open-apple, control, reset
For the internal drive (.d1) type in:
C0EA (press enter after each of these)C0D4C0D2C0D0C0E9 (Internal drive is on)C0E8 (drive is off)The first external drive (.d2) commands are similar:
C0EBC0D2C0D1C0E9 (on)C0E8 (off)Thanks for the clue.
I have no idea how to use such a tachometer, but after comparing speeds visually with my known "good" external drive, I see no issue.
Belts seems fine; exchanged them, no issue.
The main difference that I can identify is that the disk with the speed 50/60 label keeps falling out when the internal Disk III is put in the right direction.
I have no idea why that happens, nor what is supposed to keep it tight.