OS_Pur, Purge keyboard buffer

Register parameters

RST 20H, DEFB $33
IN:
     -

OUT, if call successful:
     Fc = 0, keyboard purged

Registers changed after return:
     A.BCDEHL/IXIY same
     .F....../.... different 

Notes

The system timeout is also reset, ie. running a loop with OS_Pur and OS_Tin in a loop never switches the machine off, even though the user never touches the keyboard.

Related calls

GN_Sip, system input line routine
OS_In, read (wait for) character from standard input
OS_Tin, read character from standard input, with timeout
OS_Xin, examine input