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From: jc58+@andrew.cmu.edu (Johnny J. Chin)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: EISA vs. ISA
Message-ID: <obO0GSq00UzxA3Q64_@andrew.cmu.edu>
Date: 13 Dec 90 22:45:50 GMT
References: <51097@eerie.acsu.Buffalo.EDU>
Distribution: usa
Organization: Carnegie Mellon, Pittsburgh, PA
Lines: 41
In-Reply-To: <51097@eerie.acsu.Buffalo.EDU>

Excerpts From Captions of netnews.comp.sys.ibm.pc.hardware:
13-Dec-90  Re: EISA vs. ISA               Robert J Miskines@ubvmsd (1877)   
>ISA is the 16-bit bus those of us with AT/Compatibles are familiar with. 
>EISA is a 32-bit bus, where the first part of the bus is ISA-compatible
>if im not mistaken... But, it has an additional set of 'fingers' for an 
>additional 16 bits to go through.. I believe this is similar to the 8/16 bit  
>slots in an AT/Compatible - the first section of the 16-bit bus is
>8-bit compatible.. you can plug 8-bit cards into it. If your card has the    
>additional 'finger set' for 16-bit work, even better.. EISA is the same way. 
>It will take already existing 8 and 16 bit cards, as well as 32-bit. 

Sorry, but I think that you are wrong.  EISA is not physically similar to ISA.
EISA looks like ISA, but the 32-bit section (pins) run in between the ISA pins
and are connected below the ISA pins.  EISA pin connections are also narrower
than ISA.  From my last comparison, ISA pins are twice as wide as EISA.  Don't
ask me how, but the connections work.  EISA slots are the same length as the
16-bit ISA slots.

*** SOMEBODY PLEASE CORRECT ME IF MY MEMORY FAILS ME NOW. ***

>the IBM name. I do not KNOW, but i have heard that MCA is inferior as far as
>potential for data throughput, but, since IBM invented & supports it, people
>(end users, 3rd party manufacturers of add-in cards, etc) have a tendency to 
>support it as well. 

MCA inferior to EISA?  This is not what I've heard.  I thought that MCA allows
for peripheral cards to talk to each other without CPU intervention.  I'm not
sure that EISA can do this.  Can it?

>As far as i know, the only 32-bit cards out yet are memory cards... Is this
>true?
Not true ... they have 32-bit network cards out already.  Check with
Racal-Interlan (formally, Micom-Interlan; sorry, I don't have their number).

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