Date   : Fri, 09 Aug 1985 10:06:37-EDT
From   : Gern <GUBBINS@RADC-TOPS20.ARPA>
Subject: Re: S-100 bus board problems

For anyone doing ANY work with an S-100 system, especially if it is
an older, possibly not IEEE-696 or even a new Z-100 which is IEEE-696,
you MUST get a copy of the book by Sol Libes and Mark Garetz.
I think the correct title is Interfacing to the IEEE-696/S-100 Bus.
It is very well written and will describe everything you need to know.

It helps if you have a copy of the standard:

IEEE Standard 696 Interface Devices
ANSI/IEEE Std 696-1983

It is Heathkit part number 500-69

A rough draft of the standard was published July 1979 in Computer
(IEEE) magazine.

The standard says the +8 lines (pins 1 & 51) must have an instantaneous
minium greater than +7V, instant max less than 25V and an average
max less than +11V.

The pin 2 is 14.5<16<35V with average <21.5

Pin 52 is the same, but negative.

As far as signals go, high state is +2V or greater on the reciever
end.

If you have an old S-100 system, therer are about 4 lines that have have
been changed, but they were never used much anyhow (Memory write lock,
etc.).

Major concern is the bus termination circuits to prevent ringing and
such.


I am doing a lot of work at home, on the side on a 6 channel stereo
sound/speech Synthesizer/joysticks (both analog and digital types)/
clock-calendar with battery backup and on-chip-leap-year.   The design
is finalized and I am workin on the PC Board layout.  It is completely
IEEE-696/S-100.   So if you have any S-100 questions, I'll take a 
stab at them.

Cheers,
Gern