Hallo Bo,
> I received the 720-D "disassembled".
You mean there exists a CBM 720 with built in drives like the CBM 8296D?
> The symptom is this: I enter a drive command, the error
> light comes on. No drive movement. If I THEN read the error
> channel (?ds$) I get nothing. If I read it directly
> (input#1,a,a$,b,c) I get 0, blank, 0,0.
Maybe a stupid question: what happens if you do (input#1,a,a$,b,c) without a
drive attached? Your "0, blank, 0,0" looks like showing un-initialised
variables ie. the showed data has not been read at all.
My guess is that something on the I/O part is brooken, either the computer-
or driveside. You can test wether part it is the drive or computer by
connecting another drive or computer to the 720 and its drive. This
crosstest should reveal which part is actually to blame.
The fact that the error LED flashes means IMHO that it doesn't understand
the command ie. the handshaking is alright so the trouble is in the
databits.
___
/ __|__
/ / |_/ Groetjes, Ruud
\ \__|_\
\___| http://Ruud.C64.org
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