IBM 5160 oddball fault
jws at jwsss.com
Thu Apr 23 11:48:14 CDT 2015
On 4/23/2015 9:20 AM, tony duell wrote:
> Yes, the cursor is generated by the 6845 on the CGA card.
Since the messages start out skewed to the right, I'd consider that
there is a stuck bit in the data written to whatever 6845 location
controls that. If you can probe the bus and the data is okay most
places, it may be noisy or corrupted to the slots. Obviously a lot of
the memory has to work for the bios to pass and run, so that is
suggesting some problems getting data to the interface slots, though
most of that is working or the display card would have failed as well.
Fault may be on the card data path as well, since so much other I/O is
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