Considering, that there are troubles with the true ISP cable, leading to the particular choice of parts which might be hard to obtain in certain areas (74VHC(T)xxx), I'd like to suggest that the newbies won't attempt to build a cable, but a dedicated programmer.

The purpose of this thread is to provide a secure and relatively easy way of getting 89Sxxx/89LPxx programmed as a first project, not to provide a "perfect" and permanent solution - the newbie might iterate to the "cable", or even better to a microcontroller-based "cable" later.

One form of it which comes back from time to time is that by Mohammad Asim Khan, which appears to be quite popular also with the members of this forum. It comes in two forms: as v3.0 and as v3.7; the key difference is the buffer IC. The remarkable features are the built-in oscillator and the mcu power switched under SW control. The published software seems to be comprehensive (although I did not evaulate its functionality), including some rudimentary provision for "manual" testing of the port/buffer.

However, to avoid further discussion, I'd stress the necessity to have no cable between the buffer and the mcu (all built on one board). Also, the cable from PC's LPT port should be either avoided (plug-in version), or a proper cable and termination should be suggested. I'd also suggest the newbie to start with this circuit, and build his application around it after he confirmed the programming works OK.

Comments, ideas, suggestions?

Jan Waclawek