From: bir7@leland.Stanford.EDU (Ross Biro) Subject: Re: 486SXs as Unix Iron? Date: Tue, 3 Nov 1992 05:29:46 GMT
In article <Bx3r3F.FoL@max.physics.sunysb.edu> dmcquaid@csws19.ic.sunysb.edu (Devin McQuaid) writes:
>In article <1992Nov2.050547.13873@news.stolaf.edu> johnsonm@lars.acc-admin.stolaf.edu (Michael K. Johnson) writes:
>>
><stuff deleted to save bandwidth>
<ditto>
Many Flames are deserved here, but they should be sent to Intel/IBM and if
someone can find an excuse Microsoft.
Note: I've directed follow up to a more appropriate group (I hope.)
The word bus in PC Land has at least 3 different meanings. Everyone so far
has been correct if you give them the benefit of the doubt about which one
they were talking about.
First as far as processors go there are two busses. The internal
busses is the one inside of the chip. All the different pieces of the
chip talk to each other on that bus. All [34]86's have a 32 bit
internal bus. There is the external bus which is how the processor
talks to some things on the mother board. The 286, 386sx, and one of
Cyrix's 486's have a 16 bit external bus. All other [34]86's
including the 486sx have a 32 bit external bus.
Now comes the expansion bus. That is the one we are most familiar
with and that is how the processor talks to the expansion cards,
drives, host adaptors, video boards... These busses come in many
flavors and some motherboards can support more than one of these
types, and they are virtually processor indepenant.
ISA (industry standard architecture) 16 bit "AT" bus
EISA (extended industry standard) 32 bit
MCA (micro channel) 32 bit
Local Bus 32 bit
This is incomplete, and an over simplification, but it gets the ideas
across.
Ross Biro bir7@leland.stanford.edu
Member League for Programming Freedom (LPF)
mail league@prep.ai.mit.edu for information