Re: S-100 Bus Active Termination Board

[lynchaj <lyn...@yahoo.com>]

Hi John!  Thanks!

Adjust R2 potentiometer so the voltage on unloaded pins is 2.7VDC.  That's right in the middle of "no man's land" between HIGH and LOW.

 

The bus terminator should improve bus electrical characteristics by reducing reflections and "bounce".  It acts a bit like a shock absorber or sound dampener.

 

Using 74LSxxx chips for bus buffers will help at lower bus frequencies also due more gentle switching characteristics.  The trouble with many modern CMOS chips is they are too fast and lead to a lot of overshoot on the leading edge of the squarewave signal.  The bus terminator will help but not eliminate the problem.

 

Thanks for the write up!  Have a nice day!

Andrew Lynch

 

 

 

On Saturday, May 18, 2013 2:56:39 PM UTC-4, monahanz wrote:

> Finally got around to writing up something on the S-100 Bus Active Terminator and Prototype board Andrew did a while back.
> Thanks Andrew!
>
> Please see here for further information.
> http://www.s100computers.com/My%20System%20Pages/Terminator%20Board/Bus%20Terminator%20Board.htm
>
> John