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From: johnk@cpqhou.uucp (John Kennedy)
Newsgroups: comp.sys.ibm.pc.hardware,comp.sys.intel
Subject: Re: Question -- 386DX versus 386SX
Message-ID: <1991Feb08.193453.8318@cpqhou.uucp>
Date: 8 Feb 91 19:34:53 GMT
References: <1991Feb7.182436.17262@athena.cs.uga.edu>
Reply-To: johnk@cpqhou.UUCP (John Kennedy)
Distribution: usa
Organization: Compaq Computer Corporation
Lines: 31

In article <1991Feb7.182436.17262@athena.cs.uga.edu> boone@athena.cs.uga.edu (Roggie Boone) writes:
>I know this has probably been asked before, but I am new to this group.
>
>Could someone please explain or direct me to an article that explains in 
>some detail the difference(s) between a full 80386 microprocessor
>(80386DX) and the 80386SX?  Are they both 32-bit processors?  I've 
>heard that the main difference is that the SX "talks" to the outside 
>world (memory, disk, etc) at 16-bits while the DX uses 32 bits.  Is this
>true and is this the only difference?  Are there any limitations on 
>the 386SX running 386-specific software?
>
>_Any_ info that can be provided (technical or not) would be appreciated.
>
>Thanks in advance.
>
>Roggie Boone   (boone@athena.cs.uga.edu)    
>University of Georgia

To the programmer, i.e. to software, the SX looks exactly like a DX.  Well,
not EXACTLY, but the differences are minor minor minor.  
The DX has a 4 GB address space (32 bits), while the SX has only a 16 MB
(24 bits) address space.  Also, the SX requires a 387SX co-processor, the
DX can use either a regular 387 or a 287.
-------------------------------------------------------------------------------
 John R. Kennedy              | Most applications of the 80386 will use real
 Compaq Computer Corporation  | mode for initialization only.
                              |
 uunet!cpqhou!johnk           |                   -- 80386 Programmer's
                              |                      Reference Manual
 "Don't tread on me."         |                                              
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