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

Chuck Guzis cclist at
Wed Jul 15 00:10:53 CDT 2015

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.


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