The BSD is the simplest programmer available. It is also up with the best on speed. It takes a few minutes to
get one running, but beware of cable length issues. They will be difficult to track down, but you can assume that
if you are having problems, and the diagram was followed, the cable is too long. Increasing the value of the
resistors can help cut ringing on longer cables, but you have to slow it down if you do that.
The BASCOM programmer is an unbuffered parallel port programmer similar to the STK-200. If has the same challenges
with cable length, so the resistance should be tweaked to compensate.
The chief advantage of this programmer is its ability to protect both the target and the PC from odd voltages when
one side is powered off. The buffers are open-drain, and each is pulled up to the Vcc of the receiving party. The
MC74LCX07 has an operating Vcc rating of 2.0 to 5.5V. In addition, this programmer is the only buffered programmer
that allows the PC and the target to operate at different power supply voltages. Great for working with 3.3V
microprocessors on a 5V PC.
The STK200 is buffered to protect the ports and to give a little integrity to the signal. With the 74HC125 it can
drive a longer cable than an unbuffered programmer, although the cable length still needs to be no longer than a
foot or so. This is probably the most widely used parallel port programmer.
The PonyProg is buffered, like the STK200, to protect the ports and to give a little snort to the signal. This
programmer is an STK-200 with the addition of an LED, which is used by avrdude to tell us when it is programming.