Tandy 1000 Programmer's Reference Manual page 230

Appendix
B
I Keyboard ASCII and Scan Codes
*
Indicates special functions performed
-
means this key combination is suppressed in the keyboard
driver
values preceded by
"X"
are extended ASCII codes (codes
preceded by an ASCII NUL)
The (ALT) key provides a way to generate the ASCII codes of
decimal numbers between 1 and 255. Hold down the (ALT)
key while you type on the numeric
keypad any decimal
number between 1 and 255. When you release ALT, the AS-
CII code of the number typed is generated and displayed.
Note: When the NUM LOCK light is off, the Normal and
SHIFT
columns for these keys should be reversed.
X
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