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An S100 Bus Front Panel.  
  Final FP Board Picture

This is a board designed and produced by Don Caprio.  All credit should go to Don, I am only describing the final production version of the board Don sent to a number of S100 bus users including myself.  This board is designed to be a shoe-in replacement for the IMSAI front panel including its hallmark set of switches.  As in the case of the IMSAI system,  the board allows you to examine RAM, deposit byte(s) in RAM, halt and single step then CPU as well as view the various status and control lines of the S100 Bus.

Step By Step Building The LAVA-10 S100 Board.
Relative to some of our other boards this one is relatively simple. The first step is to examine the board carefully for scratches or damaged traces. Use a magnifying glass if need be.  Next solder in all the required IC sockets, resistors, resistor arrays, capacitors, jumpers, dip switches and the voltage regulator.   Place the board in your S100 bus and check you are getting +5V on all the appropriate pins of the IC sockets.

Be sure you put the resistor arrays in with the correct orientation for pin 1. It is easiest to install the indicator LED's first.  Check the LED orientations by grounding the appropriate pins of the empty sockets or the LED itself. If the LED's don't light up switch the orientation. Then solder the LED's into place.   The choice of color for the LED is up to you.  I just happen to have a lot of yellow LED currently. 

For the switches be sure you use "center position off" switches for the right most 5 switches. The reaming 16 switches are two position on, only, switches.   It's best to solder in one pin of each switch, adjust all their positions and then solder the other two pines of each switch.

There is a small silkscreen labeling error on the board.  The "RUN" and "HOLD" labels are switched on the board.  You can use two small paper stick-on labels to correct this if you like.

I find the board needs to have the MWRT jumper (under U5) installed to function.  It seems to work even with the SMB in the bus. With the MWRT jumper in place any other MWRT generating circuit on any other CPU board should be inactivated.  You don't want two MWRT signals being generated on the same bus.  Here is a picture of the board in my small test S100 box:-
  Board in test Box

Jumper Configurations

 Here are the jumper configurations used on this board:-   


Jumper Name Description ON OFF
JP6 - pSync Term
Terminate the Psync bus signal - Pin 76 IF your system does not have an active terminated bus (DEFAULT) System already has active termination
PROT Write protect all RAM in system Pin 70 tied to ground (DEFAULT) to inactivate write protect Pin 70 not grounded. RAM cannot be written to by CPU
JP5 - SSW_DSBL Sense Switch Disable - Pin 53 Pin 53 tied to ground (DEFAULT) Pin 53 no grounded
MWRT Enable MWRT from FP - Pin 68 The S100 bus MWRT signal is generated on this board The S100 bus MWRT signal is generated by another board in the system
UPROT Enable UPROT - Pin 20 Enable RAM to be written to Disable RAM writing

To test the board, power up your computer.  Hit the "RESET" switch and then flip the "RUN" switch upward.  Your computer should signon. Type a command to display memory such as:-

As your computer is displaying RAM if you press the "STOP" switch the computer display will halt.  You can then "SINGLE STEP" the CPU by repeatedly pressing the right most switch.  If you flip the "RUN" switch upwards the CPU will continue on as before.  All the time the appropriate Address, and Status lines LEDs will be displayed.

I have not gotten the Examine/Deposit/Deposit Next switches to work in my system.   It could be this board is not able to keep up with the 10Mz Z80 CPU I have in this system
If others have more luck please let me know.

Realizing that a number of people might want to utilize a board like this together with Don Caprio and a group of people on the  Google Groups S100Computers forum, "group purchases" are made from time to time.  Join and contact the group if you would like to be involved in this project or contact Don directly.
The links below will contain the most recent schematic of this board.
Note, it may change over time and some IC part or pin numbers may not correlate exactly with the text in the article above.

FRONT PANEL PARTS LIST      (12/14/2014)
Most current KiCAD files for this board


Other pages describing my S-100 hardware and software.
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This page was last modified on 05/14/2016