Newsgroups: comp.arch
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: 80486 vs. 68040 code size [really: how many regs]
Message-ID: <1989May20.223228.2456@utzoo.uucp>
Organization: U of Toronto Zoology
References: <948@aber-cs.UUCP> <8125@killer.Dallas.TX.US> <427@ssp2.idca.tds.philips.nl>
Date: Sat, 20 May 89 22:32:28 GMT

In article <427@ssp2.idca.tds.philips.nl> pb@idca.tds.PHILIPS.nl (Peter Brouwer) writes:
>>But there's one problem: Types. On a 68000, shorts and ints are 16
>>bits, longs are 32 bits...
>Are you sure this is correct? The compilers I have used work with shorts as
>16 bits ( word ) and ints and longs as 32 bits ( long word )...

On the 68000 and 68010, there was no consensus on this, and both choices
were found in operational compilers.  32-bit ints are generally better,
and the common operations were present, but some of the less common ones
(e.g. multiply) weren't, and most everything took an efficiency hit from
32-bit data on a 16-bit bus.  The width of int is supposed to be "the most
natural width", but for the 680[01]0 that could go either way, depending
on the implementor's prejudices.
-- 
Subversion, n:  a superset     |     Henry Spencer at U of Toronto Zoology
of a subset.    --J.J. Horning | uunet!attcan!utzoo!henry henry@zoo.toronto.edu