To allow rapid entry of as many as 15 characters into a program with one keystroke by redefining BASIC special function keys.
KEY function_key,string_expression
KEY ON
KEY OFF
KEY LIST
function_key is the number of the key to be redefined. 1 corresponds to F1; 10 corresponds to F10. Use 30 and 31 to represent keys F11 and F12.
string_expression is the key assignment. Any valid string of 1 to 15 characters may be used. If a string is longer than 15 characters, only the first 15 will be assigned. Constants must be enclosed in double quotation marks.
KEY LIST displays the entire 15-character assignment for each key.
KEY ON displays across the bottom of the screen the first 6 letters of the strings assigned to keys F1 through F10.
KEY OFF erases the display of the key assignments from the screen.
Assigning a null string (length 0) disables the key as a function key.
When a function key is redefined, the INKEY$ function returns one character of the assigned string per invocation. If the function key is disabled, INKEY$ returns a string of two characters: the first is binary zero; the second is the key scan code.
'Assign a string to F1
KEY 1. "F1 function key"
'Display key assignments
KEY ON
INPUT "Press the F1 key"; x$
PRINT x$