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From: doug@edge.UUCP (Doug Pardee)
Newsgroups: comp.misc,comp.sys.m68k,comp.sys.mac,comp.sys.ibm.pc
Subject: Re: The New Chips
Summary: Why IBM chose 8088 for PC
Keywords: Intel IBM
Message-ID: <1029@edge.UUCP>
Date: 1 Feb 88 19:45:51 GMT
References: <4746@watdragon.waterloo.edu> <4227@utai.UUCP>
Organization: Edge Computer Corporation, Scottsdale, AZ
Lines: 60

>IBM used the 80xx stuff because they owned Intel.

As many folks have already pointed out...  this is a pure crock.  IBM
didn't own anything of Intel until long after the PC was well established.
And then they only bought about a 1/4 interest, and they've sold that off
(before the October stock market crash, the lucky dogs!)

>and the 802xx stuff was coming out around then

More nonsense.  The 80286 wasn't even thought of when the PC was designed.
 - - - - -
"Sherman, set the Wayback machine for 1980, location: Boca Raton, Florida."

Here we find the designers of the PC trying to decide which CPU to use.
The obvious choice is the Z-80.  The big problem with the Z-80 is that
*everybody* uses it -- it'd be easier to differentiate the product if
it used a different CPU.  Like maybe a 16-bit CPU.  Sure!  That would
give it an edge in the market.  And maybe allow more than 64K of memory
without bank-switching!

Let's see, who makes 16-bit CPUs...  Intel makes the 8086.  For 64K programs,
it's as easy to program as the Z-80, and there's an 8080-to-8086 translator
program available.  The 8086 is a bit yucky for bigger programs, but it sure
beats the bank-switching that would be needed for a Z-80.

Zilog makes the Z-8000 series.  The Z-8002 can only address 64K, but the
Z-8001 can address 8 Meg using an even messier segmented addressing scheme
than the 8086, one which requires the addition of the Z-8010 MMU chip in
order to use effectively.  Ick, bank switching would be easier.

Motorola makes the 68000, but by company policy they won't sell them for
use in home computers.

DEC makes the LSI-11.  But it's expensive and only addresses 128K.  And
buying a single-sourced critical component from a competitor is risky
business.  No way!

There are a bunch of oddball chips from manufacturers like Fairchild and
National Semiconductor, but none are serious contenders for the design.

The only real possibilities are the 8086 and Z-8000.  The decision is made
easier because there's an 8-bit-bus version of the 8086 (the 8088).  This
significantly reduces the number of other chips needed in the design --
albeit at a definite reduction in performance on any 16-bit operations.

So the choice is fairly obvious.  And "the rest is history".
 - - - - -
The point that most people miss when they berate IBM for having gone with
Intel is that the 68000 was *not* an available option at the time.  A few
years later, Apple would get its foot in the door with the Lisa (not a home
computer), and then managed to pry the door wide open with the Macintosh.

Other than the 68000, what would *you* have designed in, hmmm?  And remember
that this is supposed to be a low-cost home computer: the standard machine
has 16K of RAM, uses cassette tape for storage, and BASIC in ROM; for the
big-time user the mother-board can hold up to 64K of RAM and you can put
two single-sided 160KB floppy disk drives in the machine.
-- 
Doug Pardee         {ames,hplabs,sun,amdahl,ihnp4,allegra}!oliveb!edge!doug
Edge Computer Corp., Scottsdale, AZ                 uunet!ism780c!edge!doug