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Gpprog is a fast and reliable PIC16F84 programmer. It is designed for speed, reliability and low wear on the PIC flash cells. A programmer schematic is available.

I wanted to write code to a PIC. I tried a few apps, but the only one I could find which worked (after a fairly brief search) was pp84 for Linux, a C port of a Pascal program which indexed everything from 1. So, with that and a few others for reference, I wrote a faster, neater piece of code which works with a tristate programmer such as in the prog84 schematic.

The schematic asks for CMOS buffers. I used two 74LS244N chips because they are what I had lying around. It worked. I do not use hardware timing, the 556 may be ignored and the remaining parallel port line pulled to earth. The programmer hardware is extremely stable and reliable. Take note of the change from a 1K to a 4.7K resistor.

It would be good to add the ability to program more types of PIC to both the hardware and the software. I will undoubtedly be doing this as the need arises. It would also be useful to rewrite the magic numbers in the pic_inb() and pic_outb() calls to use functions which control each line individually (as in picprg) and probably allow the use of a non-tristate programmer.