@Aurangzeb:

There is no need to compensate for the drop of T3, since the instructions say to measure Vpp at pin 31 of the socket, which is after T1. I would normally expect the drop across T1 to be ~0.1, not 0.7.

I don't know what requires 12.75 volts, but it's apparent that "H" is supplied through R8 and D2, from Vcz.

Regards,
Mike

@Charles:
To label this programmer a "kitchen table programmer" is an insult. It is clear to me that Mr. Haque is building it. In some homes, the kitchen is the best place for building things.

This programmer is well built.....And to top it off it is free. It may eventually be well built if Mr. Haque can get the instructions explained.

I agree in principle if not in tone with Erik; unless you already have EPROM devices, an eraser and a programmer, it is a much more effective use of your time and money to begin with In System Programmed processors.

IMO, no beginner should be purchasing devices which require an external programmer.

But that's all beside the point; Mr. Haque deserves our consideration.

Regards,
Mike