Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!gatech!rutgers!bellcore!tness7!ninja!sys1!techsup!cpe!neese
From: neese@cpe.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: GATHER and say NO to MCA!
Message-ID: <12400006@cpe>
Date: 5 Jul 88 13:52:00 GMT
References: <42900016@uicsrd.csrd.uiuc.edu>
Lines: 46
Nf-ID: #R:uicsrd.csrd.uiuc.edu:42900016:cpe:12400006:000:2120
Nf-From: cpe.UUCP!neese    Jul  5 08:52:00 1988


>>1) MCA is cleaner, newer, nicer, etc etc:
>>	All true, all irrelevant. On a bus, what works is what counts!
>
>This is true.  However, what is NOT true is the claim that the AT bus
>"works".  No 32-bit data/address path, insufficient DMA and interrupt
>support, insufficient attention to loading and timing details essential
>to truly high-speed operation, and a god-awful electrical emissions
>characteristic.  I don't blame IBM one bit for getting rid of the damned
>thing.

What kind of adapter are you going to plug into your 32bit bus slot?  A memory
card?  Well that is fine, but every MC Memory card I have seen slows the over
all throughput by up to 400% when accesses occur on this card.  Show me where
the MC Bus actually helps and stop with the vague comparisons.

>>3) MCA handles multiple CPU's.
>>	So does the AT bus. A kludge, true,
>
>Not a kludge.  A disaster.  True coprocessing is damn near impossible.

The implementation in the MC bus is better, but overhead is high.  True
coprocessing is NOT damn near impossible.  It takes more attention to detail.
Do your homework before making brash statements.

>>My conclusion: the clone-makers need to pick a 32-bit AT bus extension
>>	standard. There is little engineering reason (right now) to go to the
>>	MCA.
>
>Unless you count greater reliability, better support for advanced architecture,
>better support for I/O, greater noise resistance, less emissions problems
>(therefore easier to get FCC type approval, therefore cheaper), etc....
>
>Not that I think that MCA is the BEST bus around, mind, but anyone who
>claims that the AT bus is sufficient is talking through his engineering
>hat.

Actually each bus has merits of its own, it is the implementation that should
decide which bus is better.  Peripherals for the MC bus cost more even if you
don't use the wizz-bang features of the bus.  The form-factor of the MC bus
limits the functionality of the adapter card as well.  This is important as
there are fewer slots in the MC implementations as compared to the AT imple-
metations of the day.

						Roy Neese
					UUCP @	ihnp4!sys!cpe!neese