How to calibrate the internal voltage sources which are programming voltage VCCP and VPP related:

(1) Enter the calibration mode by depressing the "TRANSFER" keys to enter the transfer mode first, then depressing the "+NAME" keys.

(2) The first one is to calibrate the VCCP voltage. Applying a voltmeter onto the pin20(-) and pin36(+) for PROM8908D, or pin16(-) and pin32(+) for PROM8908B, of any slave socket to get the reading value. Repeatedly depressing key1 to decrease, or key2 to increase its value until the required 5.0 Volts was reached. Depressing key3 to end this procedure and go to next one for VPP calibration.

(3) Apply the probe to the pin20(-) and pin3(+) for PROM8908D, or pin16(-) and pin1(+) for PROM8908B, where the VPP value is measured. Using the keys the same way as above to set its value to 12.0 Volts.

After the calibration is completed, it takes effect immediately on all following actions and the power-on after it. This new calibrated value will be stored in a non-volatile memory.

The calibration has to be taken at a period of about each three months or when there is suspicious on its value.

How to choose the voltage range for verify action:

Each time after the programmer power is on, the programmer will use 5.0V as the default value for verifing in the VERIFY and in the COPY command. But the user can change this default, verifing the device at a high and a low margin voltage value with two possible range to choose(5.0V+/-10% or 5.0V+/-5%).

(4) The last step in the calibration procedure is to decide which one of the three possible verifing voltage to use. After the type of verify was selected, it will effect on all devices until the power is off or it is re-selected.