klehr@sun.soe.clarkson.edu (Tom Klehr) (08/28/89)
I've got a problem with a used C-128D. If anyone can help me, it will be
appreciated.
The problem lies within the internal drive or with its connection to the
computer part of the machine. As best as I can see it, the computer-
drive connection fails when there is substantial communication going on
between the two. It will format a disk correctly (I can read it in another
drive). If I hook up an external 1541 to the machine, the 1541 works
correctly.
However, if I try to directory the internal drive, the drive light comes on,
but I get the cursor back. It stays this way for as long as I can stand it.
It I hit return, the drive light goes out and I get the ready prompt back.
Saving files will return the cursor, and the error message OK, but the files
are left unclosed. If I try to load from the drive, I usually never get the
cursor back, unless I warm-boot it.
I did try the burst-read routine found in the 1571 user's manual on a good
disk in the internal drive. It read the sectors fine, but it gave an
I/O error (I forget which one) before it did read them in.
One more problem it has is that the drive never stops running. I'm used to
the plain 1571 drive, but I'm not sure where I am in this drive (different
chips and signals).
I assume that it's a problem in the 6522 chip (computer-communications one),
or in the inverters connecting it to the serial bus lines, but before I go
pulling out soldered chips, I want to know if anyone else has had such a
problem, and can point me in the right direction.
Thanks in advance.
Tom