Front panel switches - what did they do?

Paul Berger phb.hfx at
Tue May 24 20:30:08 CDT 2016

On 2016-05-24 9:30 PM, Eric Smith wrote:
> On Tue, May 24, 2016 at 3:09 PM, Brent Hilpert <hilpert at> wrote:
>> Yes, I examined this in some detail last year after mention on the list, and wrote it up:
> That's a great write-up! Thanks!
> I'm not sure about how IBM TROS was driven, but the core-rope memory
> I've examined was not from an AGC and didn't use the switching core
> technique, so I wouldn't consider that decode technique to be an
> inherent property of core rope memory, although it's certainly clever.
IBM TROS see United States Patent US3432830, If you have access to old 
issues of the IBM Journal of Research and Development there is 
apparently an article in the September 1964 issue.

Other control stores used in early 360s was BCROS this is a capacitive 
memory using 2 capacitors for every bit, this is not the design used in 
the 360/30 but was used in higher end machines because it was faster.    
There is an article describing this control store in IBM Journal of 
Research and Development July 1968. The 360/30 used what is called CCROS 
it is described in a   March 1966 IBM Journal of Research and Development

IBM Journal of Research and Development scans are available on IEEE 
Explorer.  There is also a breifer description of all three in the book 
"IBM's 360 and Early 370 Systems" beginning on page 210.


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