List of Programmed Data Processors

Programmed Data Processor was the name adopted by Digital Equipment Corporation for all its early computers. (Reportedly, it was adopted to avoid worrying its early venture capital backers; at the time, almost all computers were large mainframes, and DEC's founders were concerned that if it appeared that they intended to compete in that market, they wouldn't be able to get funding.)

The name was dropped starting with the VAX. The other PDP families which became actual products for DEC (most included more than one model) were:

Family/Machine	Word Size	Comment
PDP-1	18
PDP-3	36	Only one built, not by DEC
PDP-4	18
PDP-5	12	First minicomputer
PDP-6	36
PDP-7	18	Original UNIX machine
PDP-8	12	First commercially successful minicomputer
PDP-9	18
PDP-10	36	DEC's mainframe
PDP-11	16
PDP-12	12	Laboratory computer, replacement for the LINC-8
PDP-14	12	Industrial controller
PDP-15	18
PDP-16		Not an actual computer; custom industrial controllers built out of Register Transfer Modules
PDP-20	36	Not a real name! Sometimes used for DEC-20 computers.

A number of other designs never existed as real machines, only on paper:

Family/Machine	Word Size	Comment
PDP-2	24	Never designed
PDP-2 ½		Jocular moniker for "CASINO" by Ed Rawson of the American Science Institute.
PDP-24	24?	Unconfirmed, mentioned in PDP-X memo 3.
PDP-K	18	Intended as a bridge between the PDP-15 and the PDP-10 family
PDP-X	16	An alternative to the PDP-11

External links

• Mark Crispin's 1986 list of PDP's