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 QuickSCREEN Details Example Contents Index |
| ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ |
| 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). |
