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Re: A V3 version of the S100 Bus System Monitor Board.

Hi John,

Please can you put me down for 1 x S100 System Monitor Board V3

many thanks

David Fry

On Thursday, March 19, 2015 at 5:26:07 PM UTC, monahanz wrote:

Now that the S100 bus XVGA video board (http://s100computers.com/My%20System%20Pages/VGA%20Board/VGA%20Board.htm)  has gone out to everybody, I would like to announce our next board…

It’s a V3 version of our tried and true SMB (System monitor Board). The original board is described here:-


The following changes/updates have been made to the board:-

  • The was a minor error on the above V2 board (pin 5 of U32), this is now corrected.

  • There was a report of the TMA 0-3 switch circuit was not working reliably with the 80386 board at high speed, this circuit has now been completely replaced/simplified with a single GAL.

  • An Intersil ICM7216D chip has been added along with 3 new Digital displays to continuously display the frequency of the bus master clock speed (PHI) in MHz.

  • A circuit and LED bar was added to continuously display the bit pattern of a user defined output port. (default, LED Diagnostic Port 05H).

  • A circuit was added to trigger an interrupt if the S100 bus ERROR* signal (pin 98) is activated.

  • A series of jumpers was added to easily attach a logic probe cable (such as a USBee or Saleae unit) for hardware debugging.

  • The LM323K 5Volt, 3Amp regulator can be replaced (in the same footprint/space) with a Pololu 5 Volt , 2.5 Amp D24V25 Switching regulator.

  • Almost all chips from the V2 board can be re-used on the V3 board. Only the ICM7216D, 3 Digital displays and GAL 22V10 are new.

Please see the bottom of the above page for more information.

I will be sending off an order for final bare boards in the next few days.  If you would like one or more boards please let me know (preferably by e-mail).  The usual arrangements ~$15/board + postage WHEN you get the board via PayPal.