Analysis of information sources in references of the Wikipedia article "Programmed Data Processor" in English language version.
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At the Joint Computer Conference, I [Edward Fredkin] met the PDP-1's architect, Ben Gurley, whom I had known slightly at Lincoln Lab. I asked him what parameters he had been given for the system's design. He answered, jokingly, "To make it from inventory"; in other words, to use the system modules that were Digital's main product up until then. In fact, Gurley designed about half the modules of the PDP-1 from scratch. In one of the greatest tours de force in the history of computer design, Gurley created the entire system in three and one-half months.. Direct link to PDF.
'"The PDP-2 was a mythical machine number, reserved in case we wanted a 24-bit computer," says Gordon Bell. "It was never defined on paper."'. Direct link to PDF.
Bell: Okay. The [PDP-2] was left to be a 24-bit machine. The [PDP-3] was a 36-bit machine, and we had a proposal out and there was an architecture for it and it basically was kind of a big overgrown PDP-1 with index registers. And anyway what happened was we had this proposal and we sold one of these. Direct link to Part 2
Bell: Okay. The [PDP-2] was left to be a 24-bit machine. The [PDP-3] was a 36-bit machine, and we had a proposal out and there was an architecture for it and it basically was kind of a big overgrown PDP-1 with index registers. And anyway what happened was we had this proposal and we sold one of these. Direct link to Part 2
Two new products, the PDP-2 and PDP-3, were proposed while the PDP-1 was in production. The PDP-2 never progressed beyond the initial stages. The PDP-3, a 36bit computer based on PDP-1 concepts, was designed but not built by the company.
The design evolved away from the original PDP-3 architecture, and it came to be called CASINO, for computer able to select internal orders.
The hardware implementation of the machine used DEC's 5 MHz 1000-series system modules and a 4-Kword memory which was later expanded to 64 Kwords.
The additional year of module design between American Research and Development's permission to construct computers and DEC's actual commencement of computer construction had permitted more low speed (500 KHz) modules to be designed. These newer modules used the same circuit techniques as their predecessors, but they used less expensive, slower transistors. These new modules were used for the I/O equipment. The PDP-1 was built from only 34 module types, including memory modules. Each module type was fully general purpose, except the five module types that were used for the analog memory circuitry.
