his board is a development board on which you can build your projects. It is suited for educational use, experiments or prototyping. The board uses the ATTiny2313 microcontroller with a 20Mhz clock. The board contains the ISP 10-pin connector for in circuit serial programming. It has also a push button reset switch. It has 15 digital I/O ports with 4 PWM output channels.
The I/O pins of the microcontroller are also available on two ML10 connectors for connecting for example the LCD-Interface board. The power can be connected via the DC connector which has a pin of 1.1mm. The power regulator supplies the microcontroller with the 5V DC power it needs. The DB9 bus connector can be hooked to the serial port of your PC for communication between the microcontroller and the PC. The MAX232 IC takes care of the voltage conversion of the RS232 voltage levels and the micrcontroller voltage levels.
for more detail: ATTiny 2313 BOARD