Hi,

Derrick Early wrote:

> As a result, I hope to build a programmer based on the
> 16c84 programmer that was located at bode.ee.ualberta.ca .

Just a few words of caution about this programmer:

* I developed this project using a 20MHz 386DX machine and have
subsequently found it to be unreliable when used with my 33MHz 486DX.
Obviously a timing problem.  I will try to fix this when I get some
spare time.  It would be useful if anybody that has successfully got
the programmer to work could let me know what type of PC they used.

* Please note that the executable packaged with the programmer info
was built for hardware using a 7406.  If you use a 7407 you must
recompile.  The Qbasic source is also intended for hardware using a
7406.  If you want to use the Qbasic program with 7407 based hardware
then use these definitions

CONST DataInv = 0
CONST VppOn = 8, VppOff = 0, VddOn = 4, VddOff = 0
CONST ClkHi = 2, ClkLo = 0, OutHi = 1, OutLo = 0

Note, due to a typo, the program erroneously suggests that you
should use ClkHi = 4.  Sorry about that.

* If you don't use LS buffers you should substitute a 7805 for the
78L05.

On a happier note, I have designed a PCB for the programmer which
should make life easier for intending constructors (it was while
testing my PCB that I found the timing problem).  The details will be
packaged with the next release of the software (i.e the one that
corrects the timing bug).  I can't promise when that will be ready
though.

It doesn't seem to be as widely known as it should be that there is
information on another 16C84 programmer available on the net.  This
one was designed by Henk Schaer and is (at least was when I last
looked) available as

ftp://sunshine.informatik.uni-wuerzburg.de:/pub/private/danny/picprog.zip

I haven't tried it but it might work better than mine :-)

Hope this information will be useful to some of you - sorry for the
junk if not.

--David

P.S. These programmers were both released as copyrighted freeware.
Nobody makes money from them.