HP 82479A Owner's Manual page 56

Keywords
MONSLOT
HLL MOHZLOT SC slot number, XOR mask, AND mask, errorcode
The parameters are as follows:
slot number - an HP 3421A slot (range = 0 - 2) containing a digital card.
XOR mask - value in the range of 0 to 255.
AND mask - value in the range of 0 to 255.
errorcode - Returns O if there were no errors, or the number of the error generated.
This subprogram sets up the HP 3421A to monitor the digital card. Byte values read from the input port
are XORed with the XOR mask, then ANDed with the AND mask. Effectively, the "1" bits in the AND
mask specify which bits affect the result, and the XOR mask determines the "1"/"0" choice for each bit.
When the result of the comparison is "0", a service request is sent to the HP-71 and the subprogram ends.
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