IBM 029 Card Punch and ASCII Machines

Eric Smith spacewar at
Tue May 12 13:31:48 CDT 2015

On Tue, May 12, 2015 at 9:20 AM, Paul Koning <paulkoning at> wrote:
>> On May 11, 2015, at 11:56 PM, Eric Smith <spacewar at> wrote:
>> Almost all DEC machines up through early VAX supported card punch
>> options. They just weren't very common other than on PDP-10.
>> PDP-8: CP08
>> PDP-10: CP10 (multiple variants) and CP20
>> PDP-11 and VAX: CP11
> Do you have any descriptions of that?  I have not seen any mention of a CP11 in any peripherals handbook, nor in any OS.  Was that a CSS product?

The CP11 might have been CSS. I wouldn't have thought so since the one
VAX site I knew that had one wouldn't likely have ordered CSS gear.
Possibly at one time they had enough need for punching cards to
justify buying CSS, but by the time I encountered it the punch was
always powered down with a dust cover over it.

>  Who built the punch engine?  What sort of interface did it use?

AFAIK, DEC didn't build any card punches; they are all OEM'd with
DEC-built interfaces. For the PDP-10 they OEM'd several different
models, possibly from multiple vendors. I don't know the details of
any of them, even though I used two different ones back in the day.

IIRC, the CP20 was a Unibus device, and might or might not have been
program-compatible with the CP11.

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