I have an 800k Sony drive that has stopped booting on a 512k or a Plus, but still reads\writes OK when attached to my IIsi. The IIsi has SWIM chip, the Compacts have the IWM chip. But I understand that the SWIM is just a combination of the IWM with another set of logic to drive the 1.4mb diskettes, known as the Sander logic, and it selects which path to use according to the diskette ID information. So the SWIM chip is controlling the drive using exactly the same logic as the IWMs should do. Both Compact logic board are using the Plus 128k ROMs, and both have booted with this drive in the past.
I can't work out what signal the IWM is not getting. The drive's onboard logic seems to be OK, because it works in the IIsi. There are a couple of small caps on the drive's logic board. I suppose it is possible some signal is just weaker than the IWM is calibrated for? The data read signal would seem to be the main candidate. Is there any known issue like this?
Rick
I can't work out what signal the IWM is not getting. The drive's onboard logic seems to be OK, because it works in the IIsi. There are a couple of small caps on the drive's logic board. I suppose it is possible some signal is just weaker than the IWM is calibrated for? The data read signal would seem to be the main candidate. Is there any known issue like this?
Rick