IBM 5150 or 5170 reference PDFs?

If you weren't already aware, MOV AH, 0 INT 16h waits for a key press (other than any kind of "shift"), and returns with the ASCII code in AL and the scan code in AH Note that the BIOS will have had an opportunity to "process" the information from the keyboard, and substitute a different ASCII code or Scan code "for your convenience" (such as "correcting" a non-standard kayboard), converting duplicated keys into their legacy values, etc. NOT FOR XT: function 10h does not do as much "processing", and will give different codes for some duplicate keys These are NOT the only BIOS functions for keyboard, and it is not hard to go below the BIOS if you want to look for non-standard combinations, such as differentiating between L, R, or both shift keys.