This is the PIC18F6520/8520/6620/8620/6720/8720 data sheet from Microchip.
The PIC18F6520/8520/6620/8620/6720/8720 family are 64‑ or 80‑pin high‑performance microcontrollers with 256 Kbit to 1 Mbit enhanced flash memory and a 10‑bit A/D converter. They feature a 16‑bit wide instruction set, up to 10 MIPS operation, and a variety of peripherals including multiple timers, capture/compare/PWM modules, MSSP (SPI/I²C), two USARTs, and a parallel slave port.
The datasheet includes detailed pin diagrams, oscillator configuration options, external memory interface capabilities (up to 2 Mbytes, 16‑bit), flash and EEPROM endurance specifications, power‑saving modes, and comprehensive electrical characteristics for industrial (‑40 °C to +85 °C) and extended (‑40 °C to +125 °C) temperature ranges.