waitkb(itype.i2.r, irow.i2.r, icol.i2.r, nsecs.i2.r)
This routine will flush any non-empty buffers for the TV's, LX or SS
and wait NSECS seconds for the next keyboard or terminate interrupt.
When a keyboard interrupt is detected, a terminate interrupt is
detected, or the timeout expires, control will be returned to the
caller. (If NSECS is LE 0, the routine will never timeout.)
ITYPE, IROW, and ICOL will be set to the interrupt type, cursor row
and cursor column (from the INTYPE routine).