Which Dec Emulation is the MOST useful and Versatile?

Paul Koning paulkoning at comcast.net
Wed Nov 1 07:59:18 CDT 2017

> On Oct 31, 2017, at 5:59 PM, allison via cctalk <cctalk at classiccmp.org> wrote:
> ...    FYI rope core was basically many
> transformers either with a wire
> in for the bit or wire around for the not bit.  The cores for rope
> didn't change magnetic state like
> coincident current cores of the bistable type as that allowed read write
> but was DRO (destructive
> read out with re-write) which is the more familiar core and why it had a
> shorter read time and a
> longer cycle time between reads.

Actually, that's not accurate.  Core rope memory (Apollo Computer style) does use memory cores.  You can find it described well on a web page by Brent Halpern that discusses that and other (transformer style) memories.  In core rope memory, the selected core has its state changed by the combined select currents, and then it delivers pulses to whichever sense lines are threaded through that core when the core is reset again.

The Electrologica X1 has a core ROM that also uses memory cores, but in a different way than core rope.


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