This "Pfutz's Programming experience with hardware" applies to:
Pinball Magic, Airborne, Flipper Football, & KingPin Pinball
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Pfutz's Programming experience with hardware
"Improper Driver Board Error"
Disclaimer: Remember that are getting hardware advice from a software person, would you let a used car salesman give you stock market advice?
Is an error message, in the dot matrix display, meaning that the Driver Board is not connected to the CPU board, or the I/O board is malfunctioning, or not powered. (something is very wrong!). The Driver Board was assigned a "number", and if this number is not correctly read, you get this error.

There is a high probability that the problem is on the I/O board. HOWEVER, it can also be: the CPU board, the ribbon cable or connectors that connect the 2 boards, or a power supply to or on the I/O board.

The pinball magic manual lists this the Driver Board circuit as:

Circuit Path of "Driver board" for board ID
"Driver Board" sheet 2 of 9 (pg 138/199)	"Driver Board" sheet 9 of 9 (pg 152/199)

Theory of operation:
The CPU reads data at an address that goes through the ribbon cable to the connector J12, then to the Chip U14. The address triggers U14.14 ("BRD_ID") signal low at CPU speeds (micro seconds). This select line goes to chip U55 which puts certain data on the data BD8 to BD11 lines. Specifically BD8=1, BD9=1, BD10=0, BD11=0. This data goes back to the CPU and these data bits HAVE to match. If they do not match, you get the "Improper Driver Board" error.

Be sure that at least these chips have the proper supply power. The schematic, as a routine, does not list those "boring" (but required!) power supply pins. Here are some internet picutres of those chips.

Power Pins of certain chips
U14 74LS138, pin 16=VCC=5V, pin 8=GND=0V	U55 74LS244, pin 20=VCC=5V, pin 10=GND=0V

To Verify that the Address and Data signals are working, you really need an Oscilloscope.

But do not forget a simple visual inspection of the ribbon cable, connectors, and BOTH sides of the circuit boards (driver board AND CPU board!). Nothing should be discolored or damaged or cracked!

Good Luck!

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