Good point Erik, I guess it was a bit burried...

Here's a copy of that post:

AT89 ISP Software - Just for those that need ISP software for the new LP devices, I have the Atmel AT89 ISP software running 100% reliable with ALL devices now. I was having some problems, and finally tracked it down to the SCK (Clock) signal line coming out of the parallel port. It was extremely rounded. I had the LPT1 set as ECP in BIOS, and this turned out to be the major problem. After switching to EPP the signal was nice and square. The rounded signal was screwing up the timing. It now works reliable with my notebook and a 25' LPT cable. If you have an AT89 ISP programmer, it works well as is with all of the new devices, but had a problem with the 8252. After reducing the value of the 100 Ohm resistors to 25 Ohms (except for the reset line) that go to the processor (not the LPT port resistors) it works great for the 8252 as well. I also layed out a PCB and added a switch for the enable lines on the 74VHC244 (5v with 3v VCC compliant) so that I could release the SPI pins in run mode. If not, the SPI pins are locked at whatever state the programmer is in. This didn't work for me as I use several SPI periferals. I have a schematic if anyone needs it. Other than that I left it stock. I left in the LM393 as ATMEL may use this feature (VCC Voltage sence 1=5V 0=3V) in the future. Just FYI...

So, in a nutshell, make sure your LPT is set for EPP mode, and change the 3 100 Ohm resistors on the SCK, MISO, and MOSI lines to 25 Ohms.

I run the Atmel AT89 ISP software out of Windoze 2000 Pro and XP (Home and Pro) and it works very well. Not the best user interface (I prefer a command line programmer - you can run it out of a batch file) but it DOES work with all of the devices listed in it. Even the new LP4052, which is why I went back to it.

Trev