[sebhc] Good news, bad news -- Robin succeeds; Message too long (>20000 chars)
ddl-cctech at danlan.com
Mon Mar 27 14:36:46 CST 2006
|The cause of the lack of serial comms was actually that the 8250 itself
|was faulty. Talk about bad luck; I had originally discounted the serial
|card having a hardware fault because I tried swapped serial cards
|between my two H89s and this had not fixed the fault. As it turns out,
|BOTH the serial cards had duff 8250s in the LP port circuit !
Back when I first bought a (new) 4-port serial card for the H8, 3 of
the 4 8250s were bad. I don't remember the exact symptom, but it wasn't
a complete failure. I think they locked up after a few characters. Heath
did not believe me. They were willing to send one replacement but no
more. I wrote several letters explaining that the good 8250 could be moved
to any of the four channels and would work fine, so the problem was likely
not anywhere else on the card. They pretended (at least I hope they were
pretending :) to be dumb and claimed that instead this proved that I must
have made a mistake assembling the card.
Later I think I saw the same problem on an H89. So either there was
a bad batch of 8250s or their design was pushing some timing parameter
to the edge and only the "best" chips worked.
ddl at danlan.*com
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