From: IVIE@cc.usu.edu (Roger Ivie)
Subject: [pups] Re: PDP-9
Date: Wed, 21 Aug 2002 01:01:07 -0700 (MST) [thread overview]
Message-ID: <01KLJHDIATV69D4L6T@cc.usu.edu> (raw)
Dennis Ritchie said:
> The 7, 9, 15 were very compatible. I think the -15
> had some scheme for using an index register, which
> the earlier ones didn't have, but it was otherwise
> pretty much identical in IS architecture.
According to Gordon Bell's "Computer Engineering", the primary differences
from the -4 to the -7 were switching from 6-bit to ASCII I/O devices and
the addition of a trap mechanism. The -9 primarily changed the memory
system, going to 2-1/2D core; it was also microcoded. The -15 went to
TTL ICs and added index registers and memory relocation. He says
"The PDP-9 instruction compatibility was acheived with three minor
exceptions about which no complaints were received", although I don't
see an explanation of the exceptions.
http://research.microsoft.com/users/GBell/Computer_Engineering/
--
Roger Ivie
ivie at cc.usu.edu
next reply other threads:[~2002-08-21 8:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-21 8:01 Roger Ivie [this message]
-- strict thread matches above, loose matches on Subject: below --
2002-08-21 19:59 [pups] PDP-9 Carl Lowenstein
2002-08-21 3:55 Dennis Ritchie
2002-08-21 9:19 ` Lars Brinkhoff
2002-08-21 9:21 ` Johnny Billquist
2002-08-22 2:06 ` Frank Wortner
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