I have a problem using the pic Erasable 16C73A micros.

Firstly I built A programmer similar to David Tait's using 7407
& BC557 combination. I used Ken Segler's programing
software. Initially on trying this programmer it did a blank
check ok, appeared to program ok but when it came to
verifying failed. Any way I got into this mess with a second
pic as well.
So not knowing if my circuit was the cause I got an adaptor
for a eprom programmer (inc. s/w). This adaptor supported
the 16c74. I added a link from pin 12 to pin 8 (Vss) this gave
the correct pin outs for the 28pin part into the 40pin socket
(pins 1-14, 27-40). Once again blank check passed, Program
appeared normal But verify failed.

Having now subscribed to this conference I have realized that
The programmers have probably blown the code protect bits
before verifying the code. The eprom programmer adaptor had
a separate fuse blow menu option and that was not used.

I have tried erasing the 16C73A's but this fails. Is there a way
to erase these parts? or have I stuffed them up!

One thing I would like to do is read back the option & fuse
bits to see if this is in fact what happened.

At this time I don't have any of my working in a pic (:<)-[

Any ideas, regards peter