M220B (PDP-8/I) schematics available

From: Tothwolf <tothwolf_at_concentric.net>
Date: Thu Jul 10 12:37:00 2003

On Tue, 8 Jul 2003, Bob Shannon wrote:
> Jim Davis wrote:
>
> > 7474's Dead d flops? whats the story on that?
>
> 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?

This reminds me of a similar problem in the JC80 systems, where 74170
chips would fail more often than anything else. I'd sure like to know what
the cause of that was...

-Toth
Received on Thu Jul 10 2003 - 12:37:00 BST