Talk:Programmed Data Processor

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Chips and internals[edit]

DEC was still selling PDP-8 chips by the bushel when I left (involuntarily) in 93 or whenever, and also the J11 (11/70 with MP hooks) chips. Anybody know if that's still happening? If so, it should be added to this article. Also, someone once told me that the PDP-8 was "just like the diagrams in CS-101, so everybody understood it", but since I never took any computer science, I couldn't say. --Ortolan88

I don't recall DEC ever actually selling PDP-8 chips as such. Intersil and Harris sold the 6100 and 6120, which DEC used in the VT78 and DECmate products. AFAIK, both have been discontinued.
I don't think the original LSI-11 chip set or the 11/23 chip set were ever offered for sale; they were only available in board-level products and systems. The T11 and J11 chips were sold as chips, but are long since obsolete. I'm not sure about the T11, but the J11 was fabbed by Harris for DEC.
The T11 and J11 never sold well enough for DEC to bother redesigning them in a more modern semiconductor process, so it became economically unviable to continue production.
The T11 was used in some Atari coin-operated video games. I've seen the J11 on some VMEbus processor cards, and in PDP-11 emulation boards for PCs. --Brouhaha


CHeaper ? slower, cleaper alternative

PDP-X and Data General NOVA[edit]

The PDP-X did not resemble the NOVA. See
--Peter Lund/ 13:27, 31 December 2006 (UTC)

I heard that the PDP-2 was built[edit]

I heard that the PDP-2 was built and there is still some being used commerially

PDP-14 1 bit??[edit]

I can't really believe that the PDP-14 was 1-bit. This site:


Claims it was 12-bit. Perhaps it is a typo? —Preceding unsigned comment added by (talk) 16:14, 27 February 2008 (UTC)

They are both right. According to the reference given in the article, "The PDP-14 was a 12 bit machine with a 1 bit register."
I assume that means that internally, the low-level hardware was a serial computer clocking through one bit at a time, but at the assembly-language level, the instruction set supported 12 bit data values. See also what the Motorola MC14500B says about the PDP-14. -- (talk) 03:29, 3 March 2008 (UTC)
The PDP-14 wasn't a "real computer", as it had no data memory or data registers; it could test external Boolean input signals and set or clear Boolean output signals. Guy Harris (talk) 19:06, 15 August 2013 (UTC)

Reason for name PDP[edit]

I worked as a software specialist for DEC from Feb 1980 - Jan 1992, and the reason we were told that it was called a PDP, was that for purposes of submitting proposals and other sales documents to the US Government Procurement Office, that the US Government only thought that "computers" were made by IBM. Therefore, we did not make computers, but Programmable Data Processors. — Preceding unsigned comment added by Jdawgaz (talkcontribs) 16:28, 12 February 2009‎

The 1960 manual for the PDP-1 says:
The Programmed Data Processor (PDP-1) is a high speed, solid state digital computer designed to operate with several types of input-output devices, with no internal machine changes. It is a single address, single instruction, stored program computer with powerful program features.
so I guess DEC did make computers in 1960. Guy Harris (talk) 21:31, 22 November 2014 (UTC)

Requested move[edit]

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

No consensus to move. Vegaswikian (talk) 20:40, 21 March 2012 (UTC)

Programmed Data ProcessorProgrammable Data ProcessorRelisted Alpha_Quadrant (talk) 03:27, 14 March 2012 (UTC) The article itself supports thie change along with several talk commemts. I no longer have PDP manuals, but as I recall, DEC always referred to the PDP series as "Programmable Data Processor", not "Programmed Data Processor." Relisted. Will leave a note at WT:COMP. Favonian (talk) 17:12, 7 March 2012 (UTC). — Preceding unsigned comment added by HarleyY44 (talkcontribs) 03:18, 29 February 2012 (UTC)

Are you sure? The PDP-1 manual and the PDP-3 spec linked to in the article use Programmed Data Processor. Regards, Letdorf (talk) 21:04, 29 February 2012 (UTC).
I always thought it was "Programmed" too, but I have no sources. Another possibility is that the wording behind the PDP acronym may have changed over time, so both may be correct. Peter Flass (talk) 20:27, 7 March 2012 (UTC)
The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

"Programmable" or "Programmed"?[edit]

So is there a source that unequivocally demonstrates whether the first "P" stood for "programmable" or "programmed" originally? (I might think it should have been the former, but that doesn't matter.) — (talk) 01:51, 23 March 2012 (UTC)

Or perhaps the "programmed" used in early documents was replaced later by "programmable", after someone realized that the latter was preferable? (Maybe this page should be called "DEC PDP" instead of "Programmed Data Processor"?) — (talk) 03:54, 26 March 2012 (UTC)
As noted above, it was "programmed" for the PDP-1. PDP-4: "programmed". PDP-5: "programmed". PDP-6: "programmed". PDP-7: "programmed". PDP-8: "programmed". PDP-9: "programmed", although they don't seem to ever call it the "Programmed Data Processor-9", they just call it a "programmed data processing system". From looking at various PDP-n manuals, they appear to have eventually stopped expanding "PDP" into anything; I guess at that point, "PDP" really meant "computer from DEC". Guy Harris (talk) 19:23, 15 August 2013 (UTC)

PDP-5 Production Number[edit]

Anyone have a source for the second number in "the first computer series with more than 1,000, then 10,000 built"? I'm good with the first one: Rifkin, "Ultimate Entrepreneur", gives "about 1,000" (pg. 59), but I'm somewhat dubious about the second. Noel (talk) 16:56, 20 September 2014 (UTC)

the statement "the company ultimately sold roughly 1,000 PDP-5s, making it the company’s best-selling computer by a factor of twenty" ( seems more credible, so the "then 10,000" (built) can sit here until . . . a logic processor notes that 10,000 is "more than 1,000" anyway. Pi314m (talk)

PDP-6 positives[edit]

This is about the PDP-6 section's comment saying

It was considered by its detractors a large minicomputer or, by DEC fans especially, Big Iron - a mainframe As a timesharing machine, it constantly outran the batch-oriented IBM System/360 and even IBM System/370-series mainframes.[citation needed]

When faced with knocking down a tree, an elephant is more useful than an army of ants.
When faced with a master file of 10 or more magnetic tapes, batch processing is far more effective than an early day timesharing system that might barely fit a TENTH of the master file online. Pi314m (talk) 08:49, 18 September 2017 (UTC)

PDP-8 competition[edit]

This page is about the PDP machines, and not even at a major level of detail for each PDP, hence the text below, part of which already is within the PDP-8 article, is parked here:

(quote) It is reported that Edson de Castro, who had been a key member of the design team, left to form Data General when his design for a 16-bit successor to the PDP-8 was rejected in favor of the PDP-11; the "PDP-X" did not resemble the Data General Nova, ( although that is a common myth.[citation needed] Pi314m (talk) 09:09, 18 September 2017 (UTC)