Reproducing old machines with newer technology (Re: PDP-12 at the RICM)

Dave G4UGM dave.g4ugm at
Wed Jul 15 13:09:26 CDT 2015

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of Chuck
> Guzis
> Sent: 15 July 2015 19:03
> To: General at; Discussion at and Off-
> Topic Posts
> Subject: Re: Reproducing old machines with newer technology (Re: PDP-12 at
> the RICM)
> On 07/15/2015 10:35 AM, Paul Koning wrote:
> > Then there was the very occasional early machine with no lights at all
> > — the CDC 6000 series is the one I can think of.  But there you had
> > the real time console status display, which was even better — updated
> > just as fast but with a whole lot more information.
> ...and that counters Neil's assertion that lights were too expensive.
> Cray didn't use lights, neither did CDC as well as other manufacturers.
> What they used was (usually) a separate processor with diagnostic
> capabilities.
> Lights and switches paled in comparison to what an intelligent diagnostic
> processor could do--you could see the state of I/O channels, the P-counter
> and the job to which it was attached, modify the status of just about
> anything in the system and--in some cases even tell the state of the cooling
> system.  Some allowed the operator to degrade system memory, allowing
> normal work to proceed using part of memory while performing diagnostic
> testing on the other part.
> Lights are a quaint holdover from the 1950s and early 60s and really a cheap
> alternative to getting system information. The console on a360/195 is an
> example of the technology carried to a ridiculous extreme.  The
> minicomputers of the 70s with their lights and switches being the last
> holdout, mostly because of cost.
> --Chuck

I rec all being told by an IBM'er that Amdahl had a patent on having a service processor, so IBM paid fees to Amdahl , but on investigation it looks like they had several:-

I also believe that Amdahl paid IBM for the use of the patents on Virtual memory. I wonder who paid most....
.. and perhaps this explains why IBM mid-range boxes did not have service processors...


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