If you are working with embedded projects usually you have concerned about how directly control computer ports like LPT or COM. Basically no one wants to mess up with driver writing or reading tons of documentations in order to send some bytes via IO port to your target board.

Earlier when DOS, win95 and win98 [...]

After unsuccessful attempts to run few programs who drive peripherals like USART and Timers on Atmega128 I decided to make JTAG debugger. I hope it will allow me to see what is really happening – is may atmega128 corrupted or something is really wrong with software or with hardware.

 
The most widely used AVR JTAGICE clone [...]