Marechiare wrote:
> Was it PDP-12 ?

No, it was a Varian 620-I with IDIIOM vector graphics display.

> What was the power transformer for?

It was a "contant voltage" transformer, essentially a power conditioner,
surge suppressor, and somewhat of a regulator.  It may also have stepped
down from a higher voltage, I don't remember.  It was definitely a big hunk
of iron that was bolted to the floor and required a jig like a engine hoist
to lift.

The Varian was a 16 bit machine that was outfitted with the maximum 32K
16-bit words of core memory that it could address.  The memory cycle time
was 1.8uS, so a immediate add to a register took 3.6uS.  The instruction se=
t
was more primitive than a dsPIC, although it did have multiply and divide
instructions.  It had no stack.

The main console was the size of a desk, with the vector graphics unit
another half a desk wide.  This computer was used for image processing
research until the late 1970s.  The plaque on the inside of the front panel
said it was manufactured in March of 1969.

The operating system that came with it was apparently designed before disk
drives were common.  It was intended to be used with tape drives.  We did
have a disk, but the OS treated it as 16 logical tape drives.  In the summe=
r
of 1975 I wrote a new operating system for it, which was in use at least
until I left RPI in 1980.  My operating system had named disk files (wow,
what a concept), device independent I/O, and a few other nice things the
original didn't have.

--=20
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