I got a shipment of parts in on Friday, including a ATMega8L that I had ordered specifically to build a BiProg programmer (seen here):
I decided to solder it together this afternoon, in between some other projects and a BBQ I'm getting ready to start.
I used my AVRISP mk II to program in the bootloader code and configuration fuses into the ATMega8L before incorporating it into the circuit. Instead of making a circuit board, I hand soldered it all together with wires on plated-through-hole perfboard. I didn't follow the plans exactly, I did a "hybrid" design somewhere in between the V3.0 and V4.1 hardware... I used a Maxim MAX232 chip for RS232 level conversion, and powered the thing off a 9V wall supply with 7805 to provide 5V to the circuitry. I made a few other changes, including a jumper to selectively supply 5V to the programming connectors, or not (in order to allow ISP in circuits that supply power). I did not include any LEDs, I'll add them sometime down the road. I did solder on both the 6 pin (AVR) ISP header, and the 10 pin (89LP) ISP header, as I'm planning on using the programmer for both micro families.
Everything went perfectly... I followed the directions and had the bootloader and AVRProg write the code and EE data into the ATMega8L. I then hooked it up to my AVR socket adapter board (the same one I use with the AVRISP mk II) and programmed/erased/verified/etc. a few ATTiny85's to test functionality. Start to finish, the project construction and testing took a total of about 3 hours.
Why did I bother with this when I already have an AVRISP mk II programmer? A few reasons... I wanted a backup programmer just in case something fails in my AVRISP. I wanted to be able to ISP the excellent AT89LP2052 and 4052 single cycle core 8051 derivatives, and my AVRISP won't handle those (the BiProg does!). Also, I wanted to build the programmer from a purely creative entertainment standpoint.
Fun project... easy and rewarding! Nothing quite like the satisfaction of making and using your own development tools - reminds me of the "Heathkit" days! ;)