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

Chuck Guzis cclist at
Wed Jul 15 16:45:27 CDT 2015

On 07/15/2015 01:49 PM, Jay Jaeger wrote:
> That would certainly be closer than any of the other examples that have
> been thrown in the discussion.  But it, of course, is much newer than
> the 1400 series.  IIRC, the discussion started when someone suggested
> that there were quite a few machines that were similar to the 1400
> series in terms of variable length.  Again, while that was true from the
> perspective of variable length data fields, it wasn't from the
> perspective of variable length instructions.

Well, you do realize that I'm having fun with you? :)

I've programmed the 1401--and while, not a 1410, it's not all that 
different.  I view it as an evolutionary dead-end, sort of like the 
80s-90s Dataflow machines.  I suppose it what it was intended to 
do--provide an easy transition from stuff like the 407 accounting 
machine-unit record genre.  It was easy to program (heck, I still can 
recall a few opcodes).  I suspect that the real 1401 lasted as long as 
it did mostly because it was a way to perform spooling of input and 
output cheaply, where printing on-line with say, a 7090 would have been 
a waste of resources.  Better to write a tape and let the 1401 do it.

My interest lies mostly in big iron and I"m not likely to see much of 
that in an FPGA implementation.  You have to admit that any hardware 
description that starts out with (page 1-2):

"Cooling for the basic computer consists of two 30-ton water-cooled 
condensing units.  These units cool only the CPU, MCS and I/O sections. 
  The MCU is air-cooled.  With the optional memory, the basic computer 
requires and additional 30-ton condensing unit.

Power for basic computer consists of one 250 kva 400 Hz motor-generator 
set.  The motor-generator set has the capability of providing power for 
the CPU, MCS, I/O and the MCU.  The optional memory requires the use of 
an additional 80 kva motor-generator set."

...and whose 1980's final version was immersed in liquid nitrogen, does 
draw one's attention--and I will confess appeals to the "big boy toy" 
aspect buried in me.

Still, there were some very notable machines from the aspect of 
architecture that would be worth resurrecting.  I'm just not sure that 
I'd consider the 1400 series to be one of them.

For example, I'd be interested in seeing, an FPGA version of a B5500--a 
remarkable machine architecturally if there ever was one.

Of course, suum cuique (your mileage may vary).


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