The `dongle' shown here (dongle.gif) was designed by Ken Huntington (kenh@compmore.net). It is perhaps unique in not `protecting' a copyright, being perfectly transparent to the sp12 software - so you can still use a plain cable with this version. And the dongle has no power requirements; the 74HC126 receives its Vcc from the port. Yet it significantly improves the signal quality. The Sck termination (as shown in progrmmr.pdf and icp_intr.pdf) becomes superfluous when using it. Some parallel ports won't reliably communicate with an AVR uC without it. Moreover, the programming lines are high-Z except when sp12 is active. Apart from powering the dongle, your parallel port will also still be able to provide power for a small target board (Icc up to about 5 mA). When using external power, the high-Z lines make the order of switch-on and connection less critical. You can switch on the target board first and then connect it to the PC, or make the connection and switch it on afterwards. But do make sure that your board resets properly! The absolute minimal `reset circuit' is a resistor of about 10K between Vcc and the uC's reset pin. A pcb layout for the dongle can be found on the sp12 Web page: http://www.xs4all.nl/~sbolt/e-spider_prog.html There are also photo's of our prototypes. A 74HC126 is preferred, but the dongle does seem to work well enough with a 74HCT126, if the parallel port provides a reasonable Vcc value.