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Article #2496Re: ORed indexes
From: tp
Date: Sun, 11 May 1986 14:06
Date: Sun, 11 May 1986 14:06
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1569 bytes
>digress.) If you set more than one of the three bits in the index register
>field, the corresponding registers were or'ed together before they were
>subtracted from the base address. Sounds handy, no? Well, no. It was
>that almost every 7090 program worked on the 7094, which means that nobody
>used the or'ing. Pfui.
The Harris H-series (24 bit architecture, proprietary OS) has a
similar wierdness. SOME instructions allow exactly what is described
above, but not in indexing, these are direct register references.
These are machines that are around today. I doubt anyone uses the
feature, since the assembler doesn't give you a way to set multiple
bits (not documented anyway). In some cases it would be nice. You
could or registers on a move operation, thus saving several or
instructions.
Terry Poot
Nathan D. Maier Consulting Engineers
(214)739-4741
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!inuxc!pur-ee!uiucdcs!convex!ndm20!tp From: tp@ndm20 Newsgroups: net.arch Subject: Re: ORed indexes Message-ID: <34500002@ndm20> Date: Sun, 11-May-86 10:06:00 EDT Article-I.D.: ndm20.34500002 Posted: Sun May 11 10:06:00 1986 Date-Received: Tue, 13-May-86 08:45:14 EDT References: <5100066@ccvaxa> Lines: 23 Nf-ID: #R:ccvaxa:5100066:ndm20:34500002:000:1021 Nf-From: ndm20!tp May 11 09:06:00 1986