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

Jay Jaeger cube1 at
Wed Jul 15 12:48:54 CDT 2015

Lots of machines supported variable length operands (like the machine
you reference in the link, IBM S/360, Burroughs, etc. etc.  However,
machines with variable length instructions not split into any kind of
word boundary are not as common.

This isn't about whether a machine was good or bad / worse or better /
or even level of historical interest.  Just whether or not it was
interesting - in particular interesting to me.  If the CDC machines like
that interest you, by all means have at them.  ;)

I note that, there isn't enough information in that manual to do what I
plan to do for the IBM 1410 - reproduce the actual machine logic.
Compare/contrast what you referred to to the documents at:

On 7/15/2015 12:10 AM, Chuck Guzis wrote:
> On 07/14/2015 09:16 PM, Jay Jaeger wrote:
>> Other than clones and the like (e.g., from folks like Honeywell), I'm
>> not aware of any other machines with a similar architecture to the 1401
>> and 1410.  Name them?
> Well, how about a bit-addressable, variable field length machine that
> had not only your basic set of floating point operations, but also
> variable-length binary, binary modulo-256 and packed BCD to a length of
> 65535 bytes (131K BCD digits)?  Circa 1969-1971:
> When you've got a few minutes to spare, try writing the VHDL for it.
> This was a Jim Thornton design, later taken over by Neil Lincoln.  Later
> versions of the machine had drastically reduced instruction sets from
> the original, culminating finally in the liquid-nitrogen cooled ETA-10.
> But really, variable-word length machines, while they made efficient use
> of storage, were pretty much limited to a character-serial
> memory-to-memory 2-address organization.  Quaint and perhaps
> interesting, but doomed from a performance standpoint.
> --Chuck

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