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From: gnu@sun.uucp (John Gilmore)
Newsgroups: net.arch
Subject: Re: multiplying with normal size result
Message-ID: <2449@sun.uucp>
Date: Fri, 19-Jul-85 02:00:30 EDT
Article-I.D.: sun.2449
Posted: Fri Jul 19 02:00:30 1985
Date-Received: Sun, 21-Jul-85 03:23:37 EDT
References: <149@mips.UUCP> <600005@pbear.UUCP> <493@mmintl.UUCP>
Organization: Sun Microsystems, Inc.
Lines: 12

>                      ...one multiplies two words and wants a word result.
> But hardware multiplies invariably generate a two word result, leaving the
> high-order word to be allowed for and/or disposed of.

I complained about this a few years ago in Computer Architecture News
in a paper reviewing the 68000.  Surprise, surprise, Motorola reads CAN
and in the 68020 they fixed it.  Both 32x32->32 and 32x32->64 are there.

> The same problem occurs for division.

Also fixed in the 68020, with 32/32->32, 64/32->32.  You also get to pick
whether you want a remainder or whether to just throw it away, like C does.