(CHKKEY(0))
Returns an integer value of 1 if there are keystrokes available in the type-ahead buffer. Returns 0 if no keystrokes are available. Use CHKKEY before GETKEY to determine if a key is available.
CHKKEY does nothing with the zero that you enter in parentheses; CHKKEY returns a value without receiving one.
The CHKKEY function is only supported in R:BASE for DOS, and will not return a valid value in R:BASE for Windows.
