Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!rphroy!caen!uwm.edu!ogicse!emory!wa4mei!holos0!lbr
From: lbr@holos0.uucp (Len Reed)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Question about different 386's ...
Message-ID: <1991Apr8.144122.576@holos0.uucp>
Date: 8 Apr 91 14:41:22 GMT
References: <1991Apr5.213536.12925@magnus.acs.ohio-state.edu> <1991Apr5.233653.1573@cs.mcgill.ca>
Organization: Holos Software, Inc., Atlanta, GA
Lines: 37

>>Also, most MSDOS programs are not 16-bit.  They are 8-bit.  How
>>else do you think I've been running them on my XT??????

It's amazing that someone could correctly describe the 80386SX as
internally 32-bit and externally (i.e., data path) 16 bit and then
completly miss the fact that the 8088 is the same animal in the 16/8
bit world.  DOS runs in 16-bit mode; full-word (16-bit) accesses
take 2 accesses on an 8088 and 1 on 8086, 80186 (not comonly used in
PCs), 80286 and above.

>Doesn't an XT have a 8086 ?
>(which is 16-bit in the same way 386SX is 32-bit)

No, it has an 8088 which is 16-bit in the same way the 386SX is 32-bit.
An 8086 is a full 16-bit processor.

8086:  16/16
8088:  16/8
80186: 16/16, additional instructions (e.g., PUSHA), on-board peripheral
       control, timer, and DMA, faster than 8086 at same clock speed.
       Often used in embedded systems.
80286: 16/16, has 80186 extra instructions.  Has "protected" mode for
       multitasking operating systems (e.g., Xenix).  Can address
       16 Mbytes in protected mode.
80386: (also called 80386DX). 32/32.
80386SX: 32/16.  Fully software compatible with DX, but will run slower
       especially in 32-bit mode (e.g., running Unix).
80486:	Intel refers to this as i486, which is a trademark.  Sort of
	like a 80386DX and a 80387 math coprocessor on one chip.  Also
	has 8Kbyte cache memory and a few extra instructions.


-- 
Len Reed
Holos Software, Inc.
Voice: (404) 496-1358
UUCP: ...!gatech!holos0!lbr