Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!usc!cs.utexas.edu!husc6!m2c!wpi!jhallen
From: jhallen@wpi.wpi.edu (Joseph H Allen)
Newsgroups: comp.arch
Subject: Re: DECSYSTEM 20
Message-ID: <3271@wpi.wpi.edu>
Date: 17 Jul 89 00:15:11 GMT
References: <3256@wpi.wpi.edu> <4173@ima.ima.isc.com>
Reply-To: jhallen@wpi.wpi.edu (Joseph H Allen)
Organization: Worcester Polytechnic Institute, Worcester, MA. USA
Lines: 28


To: johnl@ima
Subject: Re: DECSYSTEM 20
Newsgroups: comp.arch
In-Reply-To: <4173@ima.ima.isc.com>
References: <3256@wpi.wpi.edu>
Organization: Worcester Polytechnic Institute, Worcester, MA. USA{Cc: 
Bcc: 

In article <4173@ima.ima.isc.com> you write:
>The PDP-6 architecture was an excellent one for its day.  It was both easy to
>program in assembler and easy to compile code for.  It would probably
>still be around if the addresses were more than 18 bits long.  They put a
>truly stupendous addressing crock into the DEC-20 but it was too incompatible
>with the regular addressing, and by then it was clear that 32-bit byte
>addressed machines, e.g. the Vax, would dominate.

>John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 492 3869
>{ bbn | spdcc | decvax | harvard | yale }!ima!johnl, Levine@YALE.something
>Massachusetts has 64 licensed drivers who are over 100 years old.  -The Globe

By the time they got to the Dec-20, I think it was the fastest single
processor DEC ever made.  I think even the high end VAX's of today only get
their speed from multi-CPUs.  The DEC-20 was about 6 on the VAX speed scale. 
The computer which replaced it (an Encore) is faster also only because it has
8 32332s.  Each of these are about 1/2 speed of the '20.

But, as you say, it's best feature is that it was fun.