PDP-11/45 RSTS/E boot problem

Jeffrey S. Worley technoid6502 at gmail.com
Thu Feb 14 21:34:27 CST 2019

I got a laugh out of this anecdote.  Of course, folks heard me chuckle
and I tried to share the joke but....  Way too geeky for public

Back in 2000-ish, I was upgrading my DG MV4000/dc to 8mb so as to be
able to run the snazzy AOS/VS II tapes I'd got along with the 9 track
drive I hacked onto the machine...

The install would start and then bomb at a certain point every time.  I
decided to work the machine hard and then pull the board and give a
good SNIFF.  This is a 15x15 inch board populated with 256kx1 drams. 
The time in the machine got the board cooking nicely, and when I
smelled a certain charred smell in the vicinity of a 74ls04, I knew it
was that magic black smoke.  I pulled a 74HCT04 from a known-good isa
card, socketed the spot and viola!  Working 8mb board.  It isn't
ALLWAYS the most expensive chip, thank God, and sometimes even us not-
as-bright guys come off with a win.

I really enjoy reading this list even though I don't contribute all
that often or anything of much value.  It is a pleasure to watch you
guys work.


On Thu, 2019-02-14 at 12:00 -0600, cctalk-request at classiccmp.org wrote:
> Re: PDP-11/45 RSTS/E boot problem

> 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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