Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!aplcen!uakari.primate.wisc.edu!zaphod.mps.ohio-state.edu!van-bc!ubc-cs!uw-beaver!zephyr.ens.tek.com!tektronix!sequent!norsk
From: norsk@sequent.UUCP (Doug Thompson)
Newsgroups: comp.sys.ibm.pc
Subject: Re: 386 and SX shortage
Message-ID: <29368@sequent.UUCP>
Date: 13 Feb 90 16:37:09 GMT
References: <29108@amdcad.AMD.COM> <63320008@hpl-opus.HP.COM>
Reply-To: norsk@crg2.UUCP (Doug Thompson)
Organization: Sequent Computer Systems, Inc.
Lines: 39

In article <63320008@hpl-opus.HP.COM> knotts@hpl-opus.HP.COM (Tom Knotts) writes:
>
>>with 486's just coming out, they are becoming the "premium" computer
>>and the 386's have little hope but to drop in price.  the 286 is going
>>to have to become _real_ cheap for people to keep buying them over
>>386sx's.
>
>I hate to admit to being uninformed, but I've been wondering what is the
>difference between the 386 and 486. Can one eventually upgrade a 386 machine
>to a 486?
>
>tom

Don't worry, most of us are also, but don't admit it. The 486 runs the same programs
as the 386 and has added 6 instructions, these are:

	Byte swap (BSWAP)	will move the bytes in the operand around from 
				little indian to big indian and vice versa
	Exchange-and-Add (XADD) good for multiprocessing operation
	Compare-and-Exchange(CMPXCHG) dittio
	Invalidate Data Cache (INVD)	self evident
	Write-back and Invalidate Data Cache (WBINVD)
	Invalidate TLB Entry (INVLPG)

these instructions add some needed functionality to the 486 for system level 
operations.

The 486 has on-chip a 487 processor and 8k of cache memory. RISC type of
technology has been used to reduce the number of cycles needed to executed
one instruction, thus allowing it to have a higher MIPS rating than the
386.

A 486 25Mhz PC, as far as I see in the rates is 10-15 MIPS.

-- 
Douglas Thompson		UUCP: ..{tektronix,ogicse,uunet}!sequent!norsk
Sequent Computer Systems	Phone: (503) 526-5727
15450 SW Koll Parkway	!"The scientist builds to learn;the engineer learns in
Beaverton OR 97006	!order to build."  Fred Brooks