Anyone playing with the 8x300 - test-drb@ccmp.vtda.org

14 May 2005

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Subject: Re: Anyone playing with the 8x300
   From: "Dwight K. Elvey" <dwight.elvey at amd.com>
   Date: Sat, 14 May 2005 12:14:26 -0700 (PDT)
     To: cctalk at classiccmp.org

Hi Allison
 It is interesting that this application didn't use
that method of I/O addressing. All I/O devices are typical
bus type devices. It has a ROM connected to the instruction
addresses that selects the I/O based on the address being
executed. They don't seem to be taking advantage of the
read modify write I/O, either. The ports are all wired as
unidirectional ports.
Dwight

There were many ways to address IO on that beastie.  The basic machine
was very unlike most micros and there was no concept of addressing
for ram in the data path.  IO was almost an after thought in many ways.
But, it was fast and being very microcoded it was useful for 
datain/process/dataout things that didn't require much or any intermediate
storage. There were whole clases of appications it was useful for but often
designers rather than and deal with it's peculiar implmentation just grew
their own from the ground up like the RX02 and SMS disks. It's lifespan
in the market was short due to parts like the 29116 and other faster 
and more commonplace micros.

Allison