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From: sandee@sun16.scri.fsu.edu (Daan Sandee)
Newsgroups: comp.arch
Subject: Re: Looking for a really odd computer
Summary: PDP-9
Message-ID: <1064@sun13.scri.fsu.edu>
Date: 9 Oct 90 13:50:45 GMT
References: <1990Oct3.234941.16768@nsc.nsc.com> <14900017@hpdmd48.boi.hp.com>
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Organization: SCRI, Florida State University
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In article <14900017@hpdmd48.boi.hp.com> sritacco@hpdmd48.boi.hp.com (Steve Ritacco) writes:
>It is my understanding that DEC actually made a few 18 bit word machines.
>It was the PDP-? (I can't remember)!
>The reason I know this is that triple-i (a company that makes typesetters)
>latched on to the architecture for their equipment, and as far as I know
>still manufacture a clone of it today (pitiful no?).

PDP-9. I did a lot of assembly code programming on it in 1971. 18-bit word,
15-bit addresses, allowing for 32K words of directly addressable memory.
The oddest thing I remember about it is how it used ASCII. Apart from its own
6-bit character set, it also stored 7-bit ASCII characters, five characters
in 2 consecutive words, with one bit unused. Called "5/7 ASCII".
(ASCII had only codes 0-127 defined. The 8th bit was used by I/O devices for
parity).

Daan Sandee                                           sandee@sun16.scri.fsu.edu
Supercomputer Computations Research Institute
Florida State University, Tallahassee, FL 32306-4052  (904) 644-7045