M220B (PDP-8/I) schematics available

From: Bob Shannon <bshannon_at_tiac.net>
Date: Tue Jul 8 16:48:00 2003

Jim Davis wrote:

<snip>

>>
>> That's been my experience, too. I have replaced as many as 8 7474s
>> at a go to get an -8/L back on its feet. I don't recall replacing
>> any other chip, as a matter of fact.
>>
>> -ethan
>>
>>
>>
> 7474's Dead d flops? whats the story on that?
> Jim
>
Good question! I've also chased down several bad 7474's in my Imlac,
and I suspect some bad 7474's on a
few HP 1000 series I/O boards I have down in the shop.

Is the 7474 a 'dog'? I've know a few TTL parts that were pretty bad,
mainly counters though. But a latch?
Received on Tue Jul 08 2003 - 16:48:00 BST