13 Aug
2013
13 Aug
'13
3:49 p.m.
On Tue, 13 Aug 2013, Dave wrote:
On 13/08/2013 21:45, Robert Ollerton wrote:
Marginal checking was a major subsytem in the AN/FSQ-7 (SAGE) computer
(1957-1983), as well as its test bed, the Whirlwind. The supply voltages
could be varied by either manual or programmatic control, and could be
switched to different frames in the system. For example, a diagnostic
program for Big Memory (64K x 33bits) would vary the voltages while
running memory test patterns. Results were printed on the line printer.
Failing bits might need an adjustment to a sense amp, or a Pluggable Unit
(PU) replaced.
Mike Loewen mloewen at cpumagic.scol.pa.us
Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/
I know on the SDS Sigma, margins were adjustable
in a step up or down from
normal via a 3 position switch on the control panel/ This signal was
chained thru all the core memory power supplies. circa 1969 and before.
On Tue, Aug 13, 2013 at 11:06 AM, John Wilson <wilson at dbit.com> wrote:
> On Tue, Aug 13, 2013 at 06:15:41AM -0500, Chris Elmquist wrote:
>> Interesting pictures. I am curious why machines of this era often have
>> a "VOLTAGE" adjustment on the front panel? Was it really neccessary
>> for an operator to adjust some voltage setting as the machine ran thus
>> requiring that adjustment to be easily accessible on the front panel?
> I dimly remember (probably from the Gordon Bell book?) that KO+crowd
> were weirdly obsessed (or maybe normally obsessed given the known failure
> modes of the time) with marginal testing. So they liked to crank things
> up to the high and low limits every so often to find parts that were about
> to stop working at the nominal voltages. So I think that's what that
> is...
>
> John Wilso
> D Bit
>
On the Honeywell L66 and similar (so possible the Multics Machines as well)
the engineers diagnostic software could vary the voltages on the PSUs so it
could check it worked "on Margins". A far as I remember we did this
routinely. I believe the Ferranti Pegasus from 1953? also had adjutable
supplies. This was a valve machine ...
Dave
G4UGM