Complete datasheet for the Atmel ATmega128, a 64-pin 8-bit AVR microcontroller with 128 KB of flash, EEPROM, SRAM, two USARTs and JTAG. The 3.01 MB PDF covers pinout, fuse and lock bits, clock options, external memory interface, peripherals and electrical limits. It is used in repair to trace control signals in industrial and hobby equipment, confirm supply and crystal pins, and set up ISP or JTAG programming. Note the M103 compatibility fuse, which changes behaviour on chips taken from older designs.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @datasheet. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.