This Atmel ATtiny85-20PU is a 8 bit microcontroller AVR with 8K of system programmable flash in a 8 pin dip package.
Atmel's itty-bitty ATtiny85 8-Bit Processor. 8K of program space, 6 I/O lines, and 4-channel 10 bit ADC. Runs up to 20MHz with external crystal. Package can be programmed in circuit.