Microchip says to remove the CP bit and erase a 16C84, you Load the Config
image with bit 4 set, Send a command 1, a command 7, a command 8 (program),
delay 10ms, then send command 1 and 7 again.

What does command 1 and 7 do? Anyone know? The reason I am interested, is my
programming software (homebrew) is acting funny. Doing the previous sequence
erases the program memory but not the data memory. If you load something
other than all 1's in the config register, the PIC writes that value to all
memory. Also when I program my fuses, it seems to shift the PC over by one
each time I program (that is I start reading from location 1 instead of 0).
Very odd.

I suspect I am not shifting out commands properly, but I can't prove that as
yet. The high-level stuff is OK because using a different driver for
LudiPipo-style interface works great. But my custom hardware and driver
seems to work fine except for the erasure of data memory and the upset when
programming the fuse word.

Anybody see anything like this before?

Regards,

Al Williams
AWC
*Solderless Stamp Prototypes at http://www.al-williams.com/awce.htm