PDP-1 as minicomputer [was RE: OT - sort of]

[Rich Alderson]

From: Tony Duell
Sent: Friday, August 13, 2010 11:19 AM

>> Yep, that makes a lot more sense.  In 1960 I suppose about the only 
>> thing to play a computer game on would have been either a mini or a 
>> mainframe - actually I think it would have had to be a mainframe.  Based 
>> on a *very* quick web search, the first PDP-8 shipped in 1964, so if 
>> that was the first mini...  Some might say the IBM 1620, introduced in 
>> 1959, was a mini but I think that is a stretch.

> THe PDP1 was around in the very early 1960s IIRC. And Spacewar, of 
> course, ran on it. I would class that machine as a mini, but others may not.

AFAICT, the first customer delivery was in 1960.  Spacewar! (the exclamation
point is part of the name) was of course *written* for the PDP-1 at the MIT
AI Lab.

At the time of its introduction, the PDP-1 was not a minicomputer.  It was
capable of addressing up to 64K of 18-bit words; even the base configuration
with 4K is the equivalent of a 12K IBM 1401 in memory capacity, and the full
64K is the equivalent of the 32K of 36-bit words available in an IBM 704x or
709x system.

What set the PDP-1 apart was that it was intended as an interactive system,
with the user seated at the console.  (DEC continued this focus in the 18-bit
product line until the introduction of RSX on the PDP-15/76 (prior to the port
to the PDP-11 family).)  In this regard, it is more similar to the IBM 1130
(introduced in 1965, as the PDP-7 was sweeping into labs everywhere) than to
the contemporary batch-oriented computers.

Arguing that anything before the PDP-8 was a "minicomputer" is revisionism.
IMAO.


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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