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WAIT Statement Details
 
Syntax
  WAIT portnumber,and-expression[,xor-expression]
 
  Argument         Description
  portnumber       An integer expression in the range 0-255 that is
                   the number of the port
  and-expression   An integer expression combined with data from the
                   port through an AND operation
  xor-expression   An integer expression combined with data from the
                   port using an XOR operation
 
The WAIT statement suspends execution until a specified bit
pattern is read from a designated input port. The data read from the
port is combined, using an XOR operation, with xor-expression,
if it appears. The result is then combined with the and-expression
using an AND operation. If the result is zero, BASIC loops back and
reads the data at the port again. If the result is nonzero, execution
continues with the next statement. If xor-expression is omitted,
it is assumed to be 0.
 
                         ----- Warning -----
  It is possible to enter an infinite loop with the WAIT statement if
  the input port fails to develop a nonzero bit pattern. In this case,
  you must manually restart the machine.
                         -------------------
 
The following example program line illustrates the syntax of the WAIT
statement:
 
WAIT  HandShakePort, 2
 
This statement will cause QuickBASIC to do an AND operation on the
bit pattern received at DOS I/O port HandShakePort with the bit
pattern represented by 2 (00000010).