OT - sort of

Rich Alderson RichA at vulcan.com
Tue Aug 17 20:03:34 CDT 2010

From: Tony Duell
Sent: Tuesday, August 17, 2010 1:35 PM

>> I did not even know there *was* a PDP-1, which is not surprising I guess 

> I can't remember just which of the PDP-n series were actually produced, 
> but it's more than the PDP-8 and PDP-11 that most people remember these 
> days. 

PDP-1:  18 bits, 1960-1964
PDP-2:  24 bits, paper design, never built
PDP-3:  36 bits, one built by a customer (DEC would sell you parts and plans)
	an extended PDP-1, unrelated to later 36-bit systems
PDP-4:  18 bits, 1962-1964; 5/8 the power at 2/3 the price.  Not popular.
PDP-5:  12 bits, 1962-1964
PDP-6:  36 bits, 1964-1965; 23 built, nearly bankrupted DEC; first commercial
	system from any manufacturer with timesharing hardware built in from
	the start; intended for AI research (LISP creator John McCarthy
	advised on the design) as well as general computing
PDP-7:  18 bits, 1964-1966; DEC's most successful model to that time, first
	use of FlipChips
PDP-8:  12 bits, 1965-1967; reimplementation of PDP-5 in FlipChips, first bus
	architecture from DEC
PDP-9:  18 bits, 1966-1969; smaller, faster PDP-7
PDP-10: 36 bits, 1967-1970+; FlipChip implementation of PDP-6 architecture
PDP-11: 16 bits, 1969-1990; DEC surrendered to the 8-bit byte IBM disease
PDP-12: 12 bits, 1970?; PDP-8/i with additional LINC capabilities
PDP-14: build-it-yourself
PDP-15: 18 bits, 1970-1975; added index register to PDP-4/7/9 architecture,
	capable of addressing up to 128K words
PDP-16: build-it-yourself

They skipped 13, and stopped calling new systems PDP-x.  The follow models
of the PDP-10 were christened DECsystem-10 and DECSYSTEM-20 (defined at first
by the processor, and after a customer revolt by the microcode and OS in the
later models).

NB:  I didn't bother to go look at the exact dates in Bell, McNamara & Mudge.
Those are close enough for government work.

Rich Alderson
Vintage Computing Sr. Server Engineer
Vulcan, Inc.
505 5th Avenue S, Suite 900
Seattle, WA 98104

mailto:RichA at vulcan.com
mailto:RichA at LivingComputerMuseum.org


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