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A V3 version of our S100 bus System Monitor Board

The V1 and V2 versions of our tried and true System Monitor Board have stood the test of time.  It's described here:-



and while it’s only a year ago since we did a V2 version, I’m toying around with doing a V3 version.


As an aside my current aim is to have a core S100 computer system of 4 solid boards:-


A 16MB Static RAM board



A V3 IDE/CF Card board



and a 80486 Master/Slave board



(Of course there are and will be other S100 boards in the future -- I working on a Raspberry Pi S100 board),


Anyway I want to get the above core board’s rock solid -- ideally to run reliably at 9-10MHz.  I think our Z80 and Propeller/Console IO boards are up to it and the VGA board “should” be OK with the 80486.


Last week we went through the exercise of tweaking the V3 IDE board, thanks, it’s gone for prototyping.


I would like to consider tweaking the V2 SMB, and I’m open to a wish list.

So far I have:-

Run wide power line traces, particularly to the HEX displays.

Label the silkscreen and jumpers better/extensively.

Redo the whole TMA 1-4 line switching circuit to be less sensitive to CPU speeds (for Gary & co.)

Add a row of 0.1” jumpers near the top of the board so essential S100 bus signals can be easily tapped into with the Saleae Logic or USBee logic probes.

Use a few GAL’s to simplify the circuits and get more board space.


Suggestions please.