Datasheet for the Microchip PIC16F84A, a classic 18-pin flash microcontroller with data EEPROM, provided as a 1.46 MB PDF. It remains a common part in older hobby projects, programmers, keyless entry and small control boards. The document details the pinout, memory map, instruction set, oscillator modes and electrical limits. Use it to check VDD, MCLR and oscillator pins on a dead board, and when reprogramming through a PIC programmer, read and save existing code first if not protected.
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.