Compact 632 KB PDF datasheet from Microchip covering the PIC16C64x and PIC16C66x microcontroller families, which include analog comparator features. Several members share the document, so the variant table is the place to match the marking printed on your chip. Typical contents are pinouts, comparator and voltage reference setup, memory maps and electrical characteristics. A technician would use it to identify pins on a populated board, check signal levels at comparator inputs and confirm package type before desoldering.
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.