iso7816_plain.c implements an interface between an RS-232 serial port and an ISO 7816 smart card, and is targeted for the Atmel AT90S2313 microcontroller in a development terminal. The source code is written entirely in C using the WinAVR tool suite. WinAVR is a suite of executable, open source software development tools for the Atmel AVR series of RISC microcontrollers hosted on the Windows platform. It includes the GNU GCC compiler (avr-gcc) for C and C++. WinAVR is provided free of charge.