Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!nrl-cmf!cmcl2!brl-adm!umd5!uvaarpa!virginia!babbage!mac3n
From: mac3n@babbage.acc.virginia.edu (Alex Colvin)
Newsgroups: comp.arch
Subject: Re: RPM-40, Transputer PREFIX, HP auto-shifted registers
Message-ID: <184@babbage.acc.virginia.edu>
Date: 29 Feb 88 14:30:07 GMT
References: <1642@mips.mips.COM> <28200112@ccvaxa> <1370@vaxb.calgary.UUCP> <6310005@hpcupt1.HP.COM> <1391@vaxb.calgary.UUCP>
Organization: University of Virginia
Lines: 13
Summary: prefix :: shift & add

> Prefix instructions in the GE RPM-40

>The HP Precision Architecture provides for these kinds of operations by its
>Shift and Add instructions.  There is a pre-shifter before one of the
>inputs to the CPU.  It allows for one of the operands to be pre-shifted by
>upto 3 bits before an addition happens.

aren't these pretty much the same?
in the former case a PREFIX is folowed by an ordinary LOAD register (or PUSH).
in the latter case an ordinary LOAD register is followed by a SHAD.

it seems that the SHAD avoids the need for a special context after PREFIX.
maybe it should be called SUFFIX.
it also has other uses.