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From: paula@bcsaic.UUCP (Paul Allen)
Newsgroups: comp.sys.ibm.pc.programmer,comp.sys.ibm.pc
Subject: Re: How is a 68000 as fast as an 80386??
Message-ID: <21661@bcsaic.UUCP>
Date: 14 Mar 90 22:24:28 GMT
References: <3666@plains.UUCP> <908@tijc02.UUCP>
Reply-To: paula@bcsaic.UUCP (Paul Allen)
Distribution: na
Organization: Boeing Computer Services AI Center, Seattle
Lines: 31

In article <908@tijc02.UUCP> rdo031@tijc02.UUCP (Rick Odle           ) writes:
[quoted stuff about comparing 68k with 386 deleted]
>
>The only fair test here is to do the test with large model.  While it
>is true that the 80x86 processors will let you execute code in a small
>model architecture,  this is only applicable to fairly small applications
>( I know this is relatively speaking, and that 10 years ago 64k of code
>was a fairly large application).  The 680x0 family architecture ALWAYS
>fetches long word addresses (32 bits), so the most fair comparision
>is the x86 large model.

But the discussion was about the 80386 versus 68k.  There's no need to
handicap the 386 with far pointers when a near pointer is 32 bits.  You
can write a 4Gb application on the 386 without resorting to large model.

>BTW, this very feature (large linear address space) on the 68k family is
>what makes it a somewhat more desirable processor to program on (no
>segments to wory about).  On the other hand, the segmented architecture
>lends itself to being able to develop position independent code easier.

The 386 has its problems (like a lack of registers and the need to remain
compatible with the brain-dead processors of the past), but it certainly
does have a large linear address space.  You're right about the segmentation.
Applications no longer need to worry about it, but it's there when the
system programmer needs it.

Paul Allen
-- 
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Paul L. Allen                       | pallen@atc.boeing.com
Boeing Advanced Technology Center   | ...!uw-beaver!bcsaic!pallen