[comp.sys.ibm.ps2.hardware] 8088 and 8086 was: <Re: Getting a free PS/2>

ghenniga@nmsu.edu (Gary Hennigan) (11/03/90)

In an article teexmmo@ioe.lon.ac.uk writes:
(Esa Holmberg) writes:
>>
>>	Once more.. PS/2 model 30 has 8086, not 8088, and
>>	model 30-H has 80286..
>
>Perhaps the reason that people make this dreadful mistake is that they
>dont know what the difference between an Intel 8088 and 8086 is.
>
>If its not too much trouble, could you tell us what the differenc eis,
>and why its important?

Matthew,

   There's really only one major difference between an 8088 and an
8086 and that's the bus size. Just in case, a bus is the way a CPU
gets it's info from the outside world, eg., memory, ports and other
assorted hardware. The 8086 was the first CPU that could be
categorized as a "PC" type, at least in Intel and IBM terms. It's
architecture was 16 bit internal and a 16 bit bus. Sounds like a good
match, but, when it was first introduced the price was outrageous even
by today's standards, so IBM, and Intel, decided to make a cheaper PC
by limiting the CPU's access to the outside world to be only 8 bits
while keeping the "power" of the sixteen bit internal architecture.
While at today's rapidly decreasing prices that doesn't make much of a
difference, at the time it allowed IBM to significantly reduce their
prices which is what was needed to really "settle" the PC into the
lives of consumers. Must have worked!
   Today I don't think many more 8088's are sold, since that mismatch
in bus and CPU can be a major bottleneck and the price/performance is
reasonable any more, but fear not the mismatch is still present in the
form of the 386sx (32 bit internal 16 bit bus)!

Well that's kind of a long explanation but I hope it helps.

--
Gary Hennigan
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