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From: halkoD@batman.moravian.EDU (David Halko)
Newsgroups: comp.sys.tandy
Subject: Re: Advanced Systems
Summary: MCA
Message-ID: <3986@batman.moravian.EDU>
Date: 18 Apr 91 18:04:30 GMT
References: <1991Mar29.162359.2428@pdn.paradyne.com> <1991Apr14.164352.28893@bilver.uucp>
Organization: Moravian College, Bethlehem, PA
Lines: 44

In article <1991Apr14.164352.28893@bilver.uucp>, bill@bilver.uucp (Bill Vermillion) writes:
> In article <3763@batman.moravian.EDU> halkoD@batman.moravian.EDU (David Halko) writes:
> 
> If you want to find out what the MCA bus is all about in a fairly easy to
> understand way, pick up the book "The Microchannel Architecture Handbook"
> published by Brady. About 300 pages and $30.00.
> 
> The other thing to remember about MCA vs ISA machines, is that MCA is a
> hardware bus standard and CPU independant, while the ISA is a bus designed
> around a bus that is expecting an iNTEL type of chip.   The IBM 6000's are
> a RISC type machine, but they are still MCA bus based, and boy are they
> FAASSTTT!
> 

If you read the literature on the IBM 6000 series (I had read initial
literature which was released about a year ago... not sure about their
newer workstations, if they have any out now), you would see that the
MCA bus which are in those workstations do not use the same MCA bus, but
rather, a derivative of the same bus- although they still call it the
MCA, there are differences.

> There have been additions to the MCA specs since the initial release of
> the IBM 80 and the Tandy 5000, most noticeably the burst mode
> and the streaming mode.   Since these are basically block  move type modes
> you don't have to give an address with each byte.  Makes them faster.
> And in the streaming mode, since you don't have to pass the addresses all
> the time, you can use the 32 bit address lines in addition to the data
> lines (in a multiplexed mode) to give you an effective 64 bit wide data
> path. 

Now, is this the PC based MCA bus or the 6000 based MCA bus??? Most likely
this is the 6000 MCA bus, since I doubt IBM had changed their PC line of
bus's after releasing the original MCA since they are trying to gain 
widespread acceptance of their new "standard"...

- Dave

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