AVR 8-bit Microcontrollers from Microchip
ATtiny and ATmega AVR 8-bit microcontrollers from Microchip (formerly from Atmel).
ATtiny Parametric Table
Useful Links
Microchip Studio
Microchip Studio is an Integrated Development Environment (IDE) for developing and debugging AVR and SAM microcontroller programs written in C, C++ and assembly language.
Downloads Archive for AVR and SAM MCUs/MPUs
The Microchip downloads archive contains older versions of Atmel Studio, AVR Studio, AVR and Arm-Based MCU/MPU Toolchains for Windows and Linux, and Advanced Software Framework (ASF) packages.