OSI C3A (finally) Booting from Floppy
Posted: Mon Nov 30, 2015 2:42 pm
My C3A system has finally booted from the floppy disk!!
I used my homebrewed 6502 logic analyser to find it was stuck trying to move the head to track zero.
Then used my saleae logic analyser on the 470 disk controller find the "step" signal was toggling
on/off at the PIA but not on the 50 pin disk interface. That lead me right to the burned out 7417 hex buffer that
drives the step signal.
I just happened to have a 7407 in the junk bin and it's a pin compatible alternative for the 7417.
With that installed the system booted from floppy. Then I realized how little I remember about how
OS65D works. I'm going to have to get out the manual.
I can now go thru my pile of diskettes and find out what I have. I know a few folks were waiting for a copy of my
FORTH diskette. As soon as I figure out how OS65D works and can copy it I will share.
john
I used my homebrewed 6502 logic analyser to find it was stuck trying to move the head to track zero.
Then used my saleae logic analyser on the 470 disk controller find the "step" signal was toggling
on/off at the PIA but not on the 50 pin disk interface. That lead me right to the burned out 7417 hex buffer that
drives the step signal.
I just happened to have a 7407 in the junk bin and it's a pin compatible alternative for the 7417.
With that installed the system booted from floppy. Then I realized how little I remember about how
OS65D works. I'm going to have to get out the manual.
I can now go thru my pile of diskettes and find out what I have. I know a few folks were waiting for a copy of my
FORTH diskette. As soon as I figure out how OS65D works and can copy it I will share.
- booting_2015_11_30_web.jpg (53.91 KiB) Viewed 2612 times