A 1.88 MB PDF datasheet for the Microchip PIC16C71x family, PIC16 microcontrollers with an 8-bit analog-to-digital converter, the x covering several members. It includes pin descriptions, ADC configuration, oscillator choices, the instruction set and electrical limits. Technicians use it to identify analog inputs, supply and reset pins and to trace sensor circuits feeding the converter. Most C-series chips are one-time programmable or windowed EPROM, so failed parts are replaced with a programmed equivalent rather than rewritten.
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.