Mr. Bannister,

Thanks for the response. Thanks for including the very helpful link and the schematic.

I was refering to VPP. Please note that it is the output of T3 and GOES DIRECTLY TO PIN 31 of the 40 pin socket. Therefore the voltage MEASURED at the OUTPUT of Regulator IC U7 should, in my opinion be 12.7 volts, to compensate for the 0.7 volts drop across T3. The datasheet for AT89C51 requires either H or 12V for its programing algorithm.

This was the reason for my contention. Kindly consider again.

Thanks

Aurangzeb