HEXMON can also check if an analog sensor exceeds a preset maximum value or falls below a preset minimum value. This is done by storing the thresholds in the maximum or minimum fields corresponding to the desired sensor, and then setting a bit in the Timestamp Control Mask (location $005C) (the high bit corresponds to the analog 7 input; the low bit, analog 0).
When the sensor reading either exceeds the maximum threshold or falls below the minimum threshold, the system timer value is copied into the sensor's timestamp location. In addition, the bit in the timestamp control mask is cleared, to indicate that either a maximum or minimum timestamp was taken.
By determining which timestamp was taken, it can be concluded that the sensor either exceeded the maximum or fell below the minimum threshold.