Why weren the multiprocessor PDP-11s released commercially?
There have been dark rumors about this for many years, all emanating from non-DEC sources with no direct experience of the multiprocessor systems. The most commonly heard “conspiracy theory” rumor is associated with the introduction of the VAX 11/780 about the same time. It holds that the 11/74 would have outperformed the VAX by a factor of (2, 4, 8, 16, pick any random number), and so DEC had to pull the PDP-11/74 to sell VAXes. Emotionally appealing, perhaps, but untrue. Also implausible in light of Ken Olsen’s well known love of the PDP series, and the PDP-11 in particular. It has also been said that the KB11-CM backplane was too expensive to manufacture and sell at a profit. However, the differences between a KB11-C and KB11-CM backplane were not extreme, and in any case all DEC’s wire-wrapped backplanes were produced on automated Gardner-Denver wirewrap machines. Complexity of that particular part was not an issue. The truth about the 11/74’s non-introduction is a rather disappoin
There are dark rumors about this, all emanating from non-DEC sources with no direct experience of the multiprocessor systems. The most commonly heard rumor is associated with the introduction of the VAX 11/780 about the same time. It holds that the 11/74 would have outperformed the VAX by a factor of (2, 4, 8, 16, pick any random number), and so DEC pulled the PDP-11/74 to sell VAXes. Emotionally appealing, but untrue. Also implausible in light of Ken Olsen’s well known love of the PDP series. It has also been said that the KB11-CM backplane was too expensive to manufacture and sell at a profit. However, the differences between a KB11-C and KB11-CM backplane were not extreme, and in any case DEC’s wire-wrapped backplanes were produced on automated Gardner-Denver wirewrap machines. Complexity of that particular part was not an issue. The truth about the 11/74’s non-introduction is that it was a disappointingly simple business decision. “The product was technically quite successful. Fina
