Again back over 2 years ago Andrew and I put together an S100 bus “System Support Board”. This board was designed to allow one to analyze many of the hardware signals on the bus by “single stepping” the CPU, setting hardware breakpoints etc. It worked in the busses 16B address space with 8 and 16 bit CPU’s.
Like the MSDOS Support board, it has proven to be very popular and reliable. Many boards were already made and distributed to users. We decided to add a few small changes to the board to improve its functionality. We are calling this board the “V2 – System Support Board”. The changes include:-
1. Add a circuit to allow any combination of the four TMA0-3 lines to be activated. This allows up to 15 slave devices on the bus
2. Latch all address lines for better display reliability with high speed CPU's
3. Optimize the reset circuit
4. Optimize the single step circuit.
5. Add a circuit to ground address lines A16-A23 when (older) non IEEE-696 CPU boards are the bus master.
6. Switch to a 3A TO-3 voltage regulator A brief description of the V2 board can be found here:-
http://s100computers.com/My%
20System%20Pages/SMB%20Board/ S100%20Bus%20SMB.htm#V2-SMB (Bottom of the page).
Like the MS-DOS support board, there will probably be some interest is in people obtaining a “commercial style” bare board like this. It would be great if we could get a volunteer to organize a group purchase of boards. I will definitely be getting 3 for myself. If you absolutely need one sooner rather than later let us know we can include you in the early “first batch”. Otherwise stay tuned for a later group purchase by (hopefully) a group member that will organize a larger purchase - at a lower price.
Please note this is a two board set. Besides the S100 board, there is another board that contains three mezzanine boards for the Hex/LED bar displays and switches. If you already have the original (V1) board you don’t need the mezzanine boards as they will work with this V2 board as well. If you don’t then you will need the two board combination.
Also if you already have the original V1 board, all the chips on that board can be transferred to this new board.