Date   : Sat, 28 Jan 1984 1412-:00CST
From   : Doug <HUNEYCUTT@gunter-adam>
Subject: Z-100/IEEE-696 (S-100)

The S-100 bus in the Z-100 is indeed IEEE-696 engineered.  The system supports
5 slots, one of which is taken by the floppy disk controller, another by the
Winchester controller (if you have one).  You can plop any IEEE-696 card into
the machine, with one noteable exception....(sigh)

  You see, even the motherboard of the Z-100 is broken into logical parts.
The memory circuitry is a 'logical' S-100 card, the video circuitry another,
and so on.  Accordig to the designer, you could DMA video pictures into the
display memory if you have a DMA device driver (which the floppy controller is
NOT)  

  PROBLE:  The CPU circuitry is configured as an IEEE-696 PERMANENT MASTER!!
This precludes the addition of a standard S-100 CPU card, as it will also want
to be a permanent master.  The Zenith folks are thinking about it.

(Note:  for those of you with a Z-100 already, look at the back.  There is a
        very long cut-out at the top (about the length of a standard S-100
        card).  Yup, they actually thought about extending the S-100 outside
        the main box.  Just think what your RFI sources could do with that!!)

Doug