Re: different architecture, was PDP 11/40 system manual

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#625468

From: Rich Alderson
Date: Tue, 14 Aug 2018 20:13

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John Levine <jo...@taugh.com> writes:

> In article
> <1355830485.555945700.866...@news.eternal-september.org>,
> Peter Flass <peter...@yahoo.com> wrote:

>> Or maybe not so obvious. With word addresses you can address a lot more
>> memory with a given-length address field. A lot of machines, like the
>> PDP-10, solved this problem by having byte instructions use a byte pointer
>> that indicated the byte within the word, and this worked well.

> That's right.  I know of a similar character addresssing kludge in the
> GE 635.  It was OK, but the profusion of byte instructions added to
> the later models of -10 suggest that it didn't work that well.

"Profusion of byte instructions"?  Lemme see, LDB, DPB, ILDB, IDBP, IBP/ADJBP.
Or are you talking about the string instructions added by the VAX crowd who
got into the microcode?  I honestly don't know of anyone anywhere who used any
of those--they were slower than hand coded loops using the original set.

-- 
Rich Alderson					  ne...@alderson.users.panix.com
      Audendum est, et veritas investiganda; quam etiamsi non assequamur,
	  omnino tamen proprius, quam nunc sumus, ad eam perveniemus.
									--Galen

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From: Rich Alderson <ne...@alderson.users.panix.com>
Newsgroups: alt.folklore.computers
Subject: Re: different architecture, was PDP 11/40 system manual
Date: 14 Aug 2018 16:13:58 -0400
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