IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

Keys 71-83 have meaning only in base case, in NUMLOCK (or
shifted) states, or in CTRL state. It should be noted that the shift
key temporarily reverses the current NUMLOCK state.
KEY # NUM LOCK BASE CASE ALl ClRL
71 7 Home (Note 1) Note 1 Clear Screen
72 8 of' (Note 1) Note 1 -1
73 9 PageUp (Note 1) Note 1 Top of Text & Home
74 - - -1 -1
75 4 ~ (Note 1) Note 1 Reverse Word
(Note 1)
76 5 -1 Note 1 -1
77 6 ~ (Note 1) Note 1 Adv Word
(Note 1)
78 + + -1 -1
79 1 End (Note 1) Note 1 Erase to EO L
(Note 1)
80
81
2
3
..v
(Note 1)
PageDown (Note 1)
Note 1
Note 1
-1
Erase to EOS
(Note 1)
82 0 INS Note 1 -1
83 DEL (Notes 1,2) Note 2 Note 2
Note 1: Refer to Extended Codes Page (3-13).
Note 2: Refer to Special Handling Page (3-15).
Extended Codes
A. Extended Functions
For certain functions that can not be represented in the
standard ASCII code, an extended code is used. A character
code of 000 (NUL) is returned in AL. This indicates that the
system or application program should examine a second
code that will indicate the actual function. Usually, but not
always, this second code is the scan code of the primary key
that was pressed. This code is returned in AH.
3-13