Heath/Zenith Z100 technical...

Jules Richardson jules.richardson99 at gmail.com
Wed Sep 11 15:31:05 CDT 2019

I just picked up a board set from a Zenith Z-100 (not sure if it was a 110 
or 120 model) which had been junked. I threw this out on the sebhc mailing 
list too, but perhaps someone here knows:

a) If the machine's keyboard is completely passive (i.e. just a bunch of 
switches), or if there's any intelligence to it,

b) If the system will start up with no boards plugged in (other than the 
bitmap display PCB) - i.e. no S100 FDC or winchester,

c) If "yes" to the previous, whether the mainboard/bitmap board will 
function on just +5V and +/-12V (i.e. without the S100 +8V and +/-16V rails)

Trying to power up what I have might be fun, but I'm really not sure about 
the lack-of-keyboard issue - if it's just switches and decoded via the 
mainboard then rigging something might be possible, but if there's some 
kind of higher level serial protocol involved then maybe it's too much 
hassle. I don't have a S100 bus machine kicking around to power things with 
at present (but of course rigging something would not be too difficult).

I'm not sure what kind of details the documentation went into, either - 
I've got a Z-89 and the docs there are extremely technical, with full 
schematics, but I'm not seeing any equivalent online for the Z100 series 
(there seems to be very little out there about them at all - came too late 
in the S100 era, perhaps?)



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