DEC handbooks at LA estate sale

Eric Smith spacewar at
Sat Feb 28 03:21:17 CST 2015

On Feb 27, 2015 12:57 PM, "Ian S. King" <isking at> wrote:
>  I believe the PDP-1 used a Flexowriter.  I suspect DEC would have used an
> IBM product over Ken Olsen's dead body.  :-)

The PDP-1 console typewriter is an IBM (model B IIRC) modified by Soroban
Engineering for use as an I/O device. It was horribly unreliable, so DEC
didn't use the same for the PDP-4 and later. CHM has copies of some angry
correspondence between DEC and Soroban.

Some PDP-1 sites used Flexowriters for offline operations, and it was
possible to add them as additional I/O, but they weren't compatible with
the PDP-1 console interface.

I think some other PDP-1 I/O options were rebadged IBM equipment with
DEC-built interfaces, but I don't have details of the specific models. DEC
didn't have the resources to build all the equipment, and just engineering
and building all of the interfaces to the OEM devices nearly bankrupted
them. They optimistically put a wide variety of not-yet-designed I/O
equipment on the price list, and the salesmen sold *all* of them to
Lawrence-Livermore. Apparently some of those DEC options only ever sold one
or two units for the entire line of 18-bit machines.

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