PDP-12 at the RICM

Rich Alderson RichA at LivingComputerMuseum.org
Mon Jul 13 14:16:21 CDT 2015

From: Kip Koon
Sent: Sunday, July 12, 2015 10:52 PM

> I would be most interested in finding out more about this effort.  Do you have
> ongoing pictures documenting this effort?  I'd love to have a PDP 8, 11, 12
> someday, but I don't have the space for something like that much less the cost
> involved so I'll have to be satisfied with emulators on my PC or eventually
> building one or more of these systems with current technology like the SBC6120
> if memory serves.  Are there other possible alternatives?  I used a PDP-8/E in
> high school and college and have been quite interested in the high capability
> PDPs like the PDP-11 Series for starters.  I didn't know there were PDP 12
> Series computers.  Are there other PDP series computers as well?

Don't confuse higher numbers with higher capabilities, or even as being related
to each other.  DEC created computers with 9 different architectures before the
32-bit VAX was even dreamed of.

The list of Programmed Data Processors goes like this:

PDP-1	18-bit word, 12-bit address
PDP-2	24-bit word, paper design only
PDP-3	36-bit word, paper design only
PDP-4	18-bit word, 13-bit address
PDP-5	12-bit word
PDP-6	36-bit word, mainframe unrelated to PDP-3
PDP-7	18-bit word, PDP-4 successor
PDP-8	12-bit word, PDP-5 successor
PDP-9	18-bit word, PDP-7 successor
PDP-10	36-bit word, PDP-6 successor mainframe
PDP-11	16-bit word, 16-bit address[2]
PDP-12	12-bit word, PDP-8/i + LINC hybrid
PDP-14	control processor for customer-built special purpose equipment
PDP-15	18-bit word, PDP-9 successor
PDP-16	Register-Transfer Module hard-wired processor, PDP-14 competitor[3]

There were later variants of some of these:

PDP-8/s, PDP-8/i & /l, PDP-8/e & /f & /m, PDP-8/A

After 1971, they stopped naming things "PDP-n", with the exception of models of
the PDP-11 (which eventually consisted of more than 20 models designated
PDP-11/nn), but even there the Pro-3x0 desktop systems were called something
else.  Later models were microprocessor-based.

The later PDP-10 models were designated DECsystem-10 and DECSYSTEM-20.

The later PDP-8 models were the DECmate, DECmate II, and DECmate III (word
processing desktop systems) and the VT-78, all based on Intersil or Harris
microprocessors which were roughly the PDP-8/e in silicon.

"high capability PDPs" = PDP-10 & follow-ons.  PDP-11?  Pfeh.


[1] 1 built by a customer, reputed to be an NSA front company.

[2] With memory management, 18 or 22, in 16-bit segments.  Late models could
    use separate instruction and data segments, for a total of 128KB in use at
    one time.

[3] Different model lines had separate sales teams, and competed against each
    other across the company for sales.

Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134

mailto:RichA at LivingComputerMuseum.org


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