Hand-wired core for ROM?

Dave G4UGM dave.g4ugm at gmail.com
Fri Apr 10 09:54:10 CDT 2015

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul
> Koning
> Sent: 10 April 2015 15:46
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: Hand-wired core for ROM?
> > On Apr 10, 2015, at 10:38 AM, geneb <geneb at deltasoft.com> wrote:
> >
> > Did the PDP14 (or any machine of that era) ever use hand-threaded (by the
> end user) core boards as ROM?
> Do you mean DEC machine?
> I don’t know any.  Certainly not any PDP-11; those used solid state ROMs, or
> in the early boot ROM cards, diode arrays.
> I think some IBM 360 models used core ROM for microcode.

Rather than cores I believe that some machines had coils with drop in ferrite slugs. I found this patent from 1972 which references IBM Patents..


I also know the Elliot 803 used ferrite transformers in its logic sections...

> Another early machine — the CDC 6000 series mainframes — used a switch
> matrix for the boot ROM (“deadstart panel”).  And the character shape data
> for the console display was originally implemented as a large pile of random
> logic, though in the 170 series it turned into a conventional ROM.
> 	paul

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