Microchip datasheet for the PIC18F1220 and PIC18F1320, 18-pin PIC18 flash microcontrollers, about 5.48 MB.

Datasheet for the STMicroelectronics STM32F205RET6, an ARM Cortex-M3 microcontroller from the STM32F2 series, in a 2.22 MB PDF.

Instruction set reference in PDF format, 758 KB; the name alone does not specify the architecture, though it sits alongside AVR documents and most likely is the Atmel…

Microchip datasheet for the PIC16F8x devices, the classic 18-pin flash and EEPROM microcontrollers of the PIC16F83 and PIC16F84 type, in a 1.97 MB PDF.