Message-ID: <1707@sun.uucp>
Date: Tue, 25-Sep-84 01:52:36 EDT
Article-I.D.: sun.1707
Posted: Tue Sep 25 01:52:36 1984
Date-Received: Sun, 30-Sep-84 00:53:49 EDT
References: <13092@sri-arpa.UUCP> <15000005@smu.UUCP>
Organization: Sun Microsystems, Inc.
Lines: 16

I have seen some claims (by Motorola, but you could ask your Intel rep)
that the 286 has rather horrendous overhead for loading segment
descriptors, such that "large model" code, which must load a segment
register for every access to an element of a larger-than-64K data
segment, indeed runs an order of magnitude slower than "small model"
code.  In the 8086 the "large model" only ran 2-3x as slow, since it
took more instructions but the load-segment-register instructions were
not slow.  Of course you can run your 286 in 8086 mode if you want
to throw away all the features but regain some speed.

My 286 manual is missing (plus I don't have a compiler that generates
large model 8086 or 286 code) -- but can someone with these resources
please check and let us know?  Intel did a lot of lying in their
anti-Motorola ads, I'd like to see if Motorola has lowered themselves
to similar tactics, or whether Intel really made a blunder of this size.