Hi Biswajit,

Check out the Atmel website and AVRFreaks.net. There is a simple serial dongle in one of the ap notes that you can use for in-system programming. You can also get the software from Atmel for driving this cable.

For our production here, rather than have production use my STK500 for programming, I built a simple board with an 89C2051 which copies code from a known good board into a target board. It's simple, push the reset button to program a part, and LEDs give status at completion. It also completes in 1/3 the time of AVR_Prog (on a 90S4433).

Dennis