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Thread: What is the most mass produced model of the PDP-11?

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    Default What is the most mass produced model of the PDP-11?

    Is there any information about number of the PDP-11 produced?
    It is possible to think that the most massed model was the UKNC (google-translate it) made in the SU. This article claims that there were more than 300,000 units produced. However it was a bit strange case. This model was almost unknown in the SU and in the new states of the former SU. I became aware of this model only after 2005. All other models of the PDP-11 were known to me since the 80s. There are several explanation to this fact. This model was never sold in shops. It also was never used in schools. It was used only in the system of professional education and much rarer in industry. This model was made very poorly and failed often. Usually those computers were distributed by sets containing 15 machines where only two of them were complete and other two can be used only as parts of local network. I can even think that it was a kind of Russian Panama.
    Anyway what is the most mass produced PDP-11? Thanks.

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    Gordon Bell's 1976 paper indicates more than 20,000 early PDP-11s made divided between a bunch of models. The most common version would have to be the PDP-11/03. The book Digital at Work has some cumulative totals for all computer lines but no breakdown by PDP model let alone PDP-11 model. (50,000 in 1975, 100,000 in 1978, 200,000 in 1980). I think the PDP-11 sold the more than the PDP-8 and the rest of the PDP line had comparatively limited numbers so you might expect about half of that to be PDP-11s. After 1980, VAX and the PC lines starting taking over a larger portion of volume.

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    If you only count a PDP-11 CPU itself and not a complete system I wonder how the volume of the DC310 T-11 microprocessor compares with other PDP-11 CPUs.

    In addition to the M8063 KXT11-AA and M7676 KXT11-AB Falcon boards there was a T-11 on every M7555 RQDX3 disk controller and in every VT240 terminal, and also on Atari System 2 arcade system boards.

  4. #4

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    Quote Originally Posted by gslick View Post
    If you only count a PDP-11 CPU itself and not a complete system I wonder how the volume of the DC310 T-11 microprocessor compares with other PDP-11 CPUs.

    In addition to the M8063 KXT11-AA and M7676 KXT11-AB Falcon boards there was a T-11 on every M7555 RQDX3 disk controller and in every VT240 terminal, and also on Atari System 2 arcade system boards.
    Yes. I think that would probably be the main contestant for most produced PDP-11 CPU. However, I wonder if they really sold 300.000 of them...
    So if the Russian numbers are accurate, that could very well be the most produced one, assuming it's a single model, and not a family.
    (No, I haven't tried reading the page.)

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    Quote Originally Posted by gslick View Post
    If you only count a PDP-11 CPU itself and not a complete system I wonder how the volume of the DC310 T-11 microprocessor compares with other PDP-11 CPUs.

    In addition to the M8063 KXT11-AA and M7676 KXT11-AB Falcon boards there was a T-11 on every M7555 RQDX3 disk controller and in every VT240 terminal, and also on Atari System 2 arcade system boards.
    Bob Supnik says the T11 sold "hundreds of thousands of units". http://simh.trailing-edge.com/semi/t11.html There is no similar listing of other 11 series CPUs but what I remember hearing elsewhere was that the LSI-11 was a huge seller with probably about 300,000 to 400,000 used in PDP-11/03s plus all the alternate uses for the chips and the F-11 accounted for the remainder of DEC's 80s production of PDP-11s. I guess that would lead to a total production of 11 series CPUs in excess of the million mark which is good for a CPU line from before 1980 and not focused on being the absolute cheapest.

    Note that the preceding are estimates based on third hand stories. I do not claim them to especially accurate.

  6. #6

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    Quote Originally Posted by krebizfan View Post
    Bob Supnik says the T11 sold "hundreds of thousands of units". http://simh.trailing-edge.com/semi/t11.html There is no similar listing of other 11 series CPUs but what I remember hearing elsewhere was that the LSI-11 was a huge seller with probably about 300,000 to 400,000 used in PDP-11/03s plus all the alternate uses for the chips and the F-11 accounted for the remainder of DEC's 80s production of PDP-11s. I guess that would lead to a total production of 11 series CPUs in excess of the million mark which is good for a CPU line from before 1980 and not focused on being the absolute cheapest.

    Note that the preceding are estimates based on third hand stories. I do not claim them to especially accurate.
    The problem is that sources like Wikipedia claims 600.000 PDP-11s were sold in total. Now, I can believe that plain T11 CPUs are outside of that scope, so VT240, RQDX3 (also DEUNA, probably the HSC-50 as well as the VAX-11/780 front end), as well as arcade games needs to be counted on top of that, which were all T11. LSI-11 might have sold some, but the 11/03 itself cannot have sold anywhere near those numbers.
    And don't forget that DEC moved on to the J11 in the 80s as well. It was used in the Pro-380 as well as the later HSC controllers.

    But the question then is - do anyone have any reliable production numbers (or sold numbers) for those CPUs?
    They certainly did not seem to get much traction outside of DEC. Some arcade games, for sure, but I'm not really aware of any other non-DEC users of the chips.

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    Wikipedia doesn't source its claim of 600,000 or I would have looked at the source to see if it breaks down sales further. What I understand was roughly half of all PDP-11s sold as computers were PDP-11/03s. DEC at the time seemed scared of letting Data General figure out what the successful markets were. I know that some DEC archives had been available to researchers which could provide a detailed accurate answer. Bob Supnik probably knows the ball park figures for most of the CPU line.

    J11 was a flop. DEC couldn't get them made in volume.

  8. #8

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    Quote Originally Posted by krebizfan View Post
    Wikipedia doesn't source its claim of 600,000 or I would have looked at the source to see if it breaks down sales further. What I understand was roughly half of all PDP-11s sold as computers were PDP-11/03s. DEC at the time seemed scared of letting Data General figure out what the successful markets were. I know that some DEC archives had been available to researchers which could provide a detailed accurate answer. Bob Supnik probably knows the ball park figures for most of the CPU line.

    J11 was a flop. DEC couldn't get them made in volume.
    As far as I know, the problem with the J11 wasn't volume, but that early production did not hit the speed target they were aiming for. Now sure they ever sorted that out, but there were lots of 11/53, 11/73, 11/83, 11/84, 11/93, 11/94, HSC-70, HSC-90, Pro-380, as well as companies like Mentec and Osprey using J11 in their PDP-11 implementations.
    In addition to speed targets, there were also issues with the FPA. Which is why various variants of the 11/8x CPU board exists, and only some of them can be fitted with an FPA at all, even though they all have the socket.
    I'm sure Supnik can provide more details about that one, since he was involved in the development of the FPA, unless I remember wrong.

    The J11 was the mainstay of all PDP-11 production after about 1983. Last model from DEC was the 11/9x released in 1990.

    Half of all PDP-11 being 11/03 sounds a bit high, but I don't have any sources for any production.

    However, searching through some market analysis documents, I found this:
    in 1986, DEC sold 16.000 of (PDP-11/03, 23 and 11 SV). 2.700 PDP-11/44. 1.000 PDP-11/24. (See http://www.bitsavers.org/pdf/dec/com...rket_Jun89.pdf, page 15)

    From that, it would seem unlikely that half of all PDP-11s ever sold would be 11/03 machines.

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    That report was late as the PDP-11 was winding up its market presence. Two other reports on bitsavers show the decline of the high end PDP-11; one describing superminis and the other 32-bit. The other sales numbers for the PDP-11 online was in the DEC Digital from 1957 to the Present* (1977) which gave a nice breakdown by system. The LSI-11/PDP-11/03 had only been out for about a year and a half but accounted for 4,750 out of about 42,000 PDP-11s while another 37,000 were PDP-8 variants and no other PDP model sold more than a thousand. This leaves a big gap of the decade of the highest PDP-11 sales volume including the Heathkit H11.

    * This strangely quoted IDC EDP Industry Report 4/22/77 not internal DEC information.

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