Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!uw-beaver!tektronix!percival!nerd
From: nerd@percival.UUCP (Michael Galassi)
Newsgroups: comp.sys.m68k
Subject: Re: 68000 68010
Message-ID: <1366@percival.UUCP>
Date: 16 Sep 88 09:11:59 GMT
References: <8968@cup.portal.com> <300001@hpclkms.HP.COM>
Reply-To: nerd@percival.UUCP (Michael Galassi)
Organization: Percy's UNIX, Portland, OR.
Lines: 38

In article <300001@hpclkms.HP.COM> ken@hpclkms.HP.COM (Kenneth Sumrall) writes:

>The 68010 isn't missing any instructions that the 68000 has, but their is
>one instruction that used to be a user mode instruction that now is a super-
>visor mode instruction.  The speedup that the 68010 would gives has been 
>quoted as about 5%.  This is accomplished through a mode called
>looping mode (or something similiar) in which small tight loops are held
>entirely in a small on chip chache, and can be executed without loading 
>opcodes from external memory.  This mode is most useful in operations
>like memory block moves and such.

>Kenneth Sumrall

The loop mode tends not to be much of a win in compiler generated
code as it nearly never gets used other than in hand optimized
library routines, the win if ever comes from the faster mul[us],
div[us], and the presence of the rtd instruction in the '010.

This is contrasted by the fact that the most common exceptions are
slower in the '010.  Most common is what I have determined by profiling
the code I write at work, and inclues the av[1-7]  (+2 periods), the
trapv (+6 periods) illegal (+4 periods), your code may have different
ideas as to what is and is not "most common".

I have consistently gotten the same results out of the two parts
when I have benchmarked them on hand-written assembly though I realy
like the rtd instruction for general purpose code and have gotten
much mileage out of the bkpt instruction when I hacked together a
replacement for our AMS emulator.

These are of course the views of someone who works a lot with
assembly language and may not mean much to those who work in
high-level languages.
-michael
-- 
        Michael Galassi     | If my opinions happen to be the same as
...!tektronix!percival!nerd | my employer's it is ONLY a coincidence,
...!sun!nosun!percival!nerd | of course coincidences OFTEN DO happen.