PDF datasheet of 2.58 MB for the Microchip PIC16C5x series, the original baseline line of small 8-bit OTP or EPROM controllers found in older appliances, remotes and simple control boards. The file name covers the whole series rather than a single part. Inside are pin diagrams, instruction set, timing and electrical specifications. Use it to confirm power and clock pins and reset behaviour when a board appears dead, and check the device suffix to select the correct memory and pinout table.
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.