CAL meaning in Computer Hardware ?

In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known accuracy, a device generating the quantity to be measured such as a voltage, a sound tone, or a physical artifact, such as a meter ruler.

The outcome of the comparison can result in one of the following:

Strictly speaking, the term "calibration" means just the act of comparison and does not include any subsequent adjustment.

The calibration standard is normally traceable to a national or international standard held by a metrology body.