PDP-11/45 RSTS/E boot problem

Paul Koning paulkoning at comcast.net
Wed Feb 13 15:02:29 CST 2019

> On Feb 13, 2019, at 3:54 PM, Ethan Dicks via cctalk <cctalk at classiccmp.org> wrote:
> ...
> It's interesting that it was a bad 7430 in yours.  I find that for
> equipment of that vintage, my usual suspects are failed 7474s and
> failed 7440s, probably 80% of the total.  Behind that, it goes 7420s
> and then maybe 7430s.

When our 11/45 failed in the MMU in 1975, my classmate Josh Rosen traced the failing path on the schematics.  When Jim Newport the field service engineer showed up, Josh described the diagnostics result that pointed at the failed path, and added "This is the failed chip" (pointing to one particular chip.

Jim asked "Why that one?"  Josh answered "because that is the most expensive chip".

It turned out he was right.


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