On Sat, 6 Jun 2015, Steven Hirsch wrote:
My Advantage decided to stop booting from floppy disks (the only media it is
capable of booting). At first it threw random disk errors, then progressed
to the point where I get an immediate "Hardware Failure" diagnostic on screen
at power up. If I reset and hit 'Enter' it starts the disk drive comes right
back with a "?" prompt and LOAD SYSTEM.
Spent some further time with the unit. I had a hunch that the "Hardware
Failure" diagnostic might be a memory parity error (the Advantage is one
of the few machines I've seen of this vintage that has a parity chip on
each bank). Starting swapping in some extra 4116s and finally brought it
to the point where CP/M signs on, the drive steps to the directory track
and dies with a an error code:
T 1 D 1 S 0010
According to the documentation:
T1 = Sync byte not found
D1 = Drive A
S 0010 = Sector 10 (decimal)
It's almost certainly not bad media. I tried several different (and
previously working) bootable diskettes with exactly the same results.
When I try to boot the GDOS demo diskette, it clears the screen, starts
making a repetitive "buzz" from the speaker and hangs.
Is anyone familiar enough with the circuit to suggest a starting point for
further troubleshooting?
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