Micro­power

1. Short out the pulse capacitor, C10, from the old 2708 25 volt pulse circuit showy on sheet 3 of the circuit diagrams. Take a lead from ‘A” of that diagram (I used the end of R5 furthest from TR2) to pin 3 of switch 2. This will provide 25 volts on pin 20 of the recipient EPROM.
2. Lift IC 2. Bend out pins 7 and 14. Use one of your two 1 Meg resistors to pull pin 7 down to 0 volts by connecting it between pin 7 and the wide track close to pin 7. Pin 7 must also be connected to Bit 6 of port 5. This is easiest done by using the through-plated hole next to the C7 legend. Pin 14 is left unconnected. Bit 6 of port 5 now controls a 25 volt/​0 volt output to pin 20 of the recipient EPROM.
3. Connect together pins 8 and 9 of switch 2 to put A10 on pin 19 of both EPROM.
4. Fortunately, IC 3 produces an All signal on pin 1. I bent pin 1 of IC’3 out and connected it to pin 11 of the same switch to provide All on pin 21 of both the donor and recipient EPROMs.
5. Join Bit 2 of port 5 to pin 6 of switch 2. This is best achieved by using the plated hole just by the TR6 legend and close to the switch. I also pulled pin 6 of the switch to 5 volts with the second 1 Meg resistor. I used the legend end of R20 for my 5 volts.

Your board is now a 2732 programmer when switch 2 is pushed in and a 2716 programmer when switch 2 is out, but only when the software is correct.

Software Modifications.

Thank you Bits and PCs for your fully documented listing. I am most grateful. First, the functions of the bits 0 to 6 of the control word that is used to control the EPROM blower.