The stand comment on diy programmers: DONT!
The topic has been discoussed several times here.

If you do your own programmer, you dont know what went wrong - the programming of the GAL/eprom/flash what ever - or the rutine you tried to program in silicon.

There are quite a few ready made programmers at reasonable prices out there.

Or go with a CPLD and make the buffer your self.

happy programming

Per Guldmann