ATMEL Atmel AVR micro controller AT90PWM216 handbook
Datasheet
This document is about the features of AVR® 8-bit microcontrollers, including high performance, low power, high performance RISC architecture, 129 powerful instructions, 32 x 8 general-purpose working registers, fully static operation, up to 1 MIPS throughput, and on-chip 2-cycle multiplier