My understanding is that such a "direct connection" depends greatly on the length and type of the parallel cable you are using. What might work with one length/type of cable might not work with another. Using the '541 solves that problem but you still need a 220 ohm (more or less) resistor on the output line that goes from the programmer to the parallel cable.



Buffer it. You have the buffer available so go ahead and send the reset signal through it too.

Why not try the following (but replace the LS541 with HCT541):



If you want to keep using the software you are using then just rewire the connections to the parallel port appropriately. But the schematic above has worked in prototype stage, PCB implementation, and with two different computers. I guess that's no guarantee that it will work for anyone else but I went through a lot of the same problems you did and I arrived at the above.

Or you could just implement the design above with the parallel port connections specified and use this software (available for both Windows and Linux).

Regards,
Craig Steiner