Circuit diagram titled Z84F, provided as a 1.03 MB PDF with no brand or revision in the name. Check the cover sheet for the full model and board revision, since close variants of this design exist. Technicians use such schematics to follow supply voltages, find where a short sits, trace signals between the chipset and peripherals and read component values. It opens in any PDF viewer. Match the marking on the PCB to the drawing before using it for measurements or part replacement.
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 @schematicslaptop. 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.