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Path: utzoo!watmath!sunybcs!kitty!peter
From: peter@kitty.UUCP (Peter DaSilva)
Newsgroups: net.micro.68k,net.micro.16k
Subject: Re: Re: PDP11s vs the micros
Message-ID: <273@kitty.UUCP>
Date: Thu, 8-Aug-85 09:49:28 EDT
Article-I.D.: kitty.273
Posted: Thu Aug  8 09:49:28 1985
Date-Received: Fri, 9-Aug-85 04:40:56 EDT
References: <1617@hao.UUCP> <847@mako.UUCP> <2422@sun.uucp>
Organization: Recognition Research Corp., Clarence, NY
Lines: 25
Xref: watmath net.micro.68k:1042 net.micro.16k:360

> As for eliminating auto +/- addressing mode, I support that decision.
> Given their decision to "back out" instructions that get page faults
> rather than dump out the internal microstate like the 68010, National

Any particular reason to do this rather than restart the instruction from
where it left off? I hadn't heard of this approach... what does the Vax
do? What are the tradeoffs.

> would have to keep shadow copies of too much internal stuff around in
> case a page fault came through.  That's a big hassle and takes chip
> real estate.  I think having full memory to memory addressing is more
> useful that auto +/-, especially for compiler generated code.  (well
> maybe not for pcc -- it's model seems to be put something in a
> register, munch on it, put it back in memory).

main(ac, av)
register int ac;
register char **av;
{
	while(*++av) {
		...
	}
}

Not an uncommon case construction in 'C'.