50 lines
1.9 KiB
HTML
50 lines
1.9 KiB
HTML
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<HTML>
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<HEAD><TITLE>QuickBASIC 3.0 - Long Entry</TITLE></HEAD>
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<BODY>
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<A HREF="ng32b68.html">[<<Previous Entry]</A>
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<A HREF="ng320.html">[^^Up^^]</A>
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<A HREF="ng33204.html">[Next Entry>>]</A>
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<A HREF="menu.html" >[Menu]</A>
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<A HREF="info.html">[About The Guide]</A>
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<HR>
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<PRE>
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<B>WAIT Wait for Port Status</B>
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<B>WAIT</B> <U>port</U>, <U>n</U>[,<U>m</U>]
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Suspends program execution until a specified bit pattern appears at a
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specified port address.
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<U>port</U> A numeric expression in the range 0 to 65535; specifies
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the I/O port to test.
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<U>n</U>,<U>m</U> Integer expressions in the range 0 to 255; they supply the
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test. <U>m</U> defaults to 0.
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----------------------------------------------------------------------
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<B>Notes:</B> QuickBASIC gets the value at port, XORs it with <U>m</U>, then
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ANDs it with <U>n</U>. If the result is zero, the process is
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repeated. If the result is nonzero, program execution
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continues with the next statement.
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To test for a 1 at a particular bit position in <U>port</U>, <U>m</U>
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should be omitted and <U>n</U> should have a 1 at the position in
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question. To test for a 0 in <U>port</U>, both <U>n</U> and <U>m</U> should
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have a 1 in the position in question.
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Note that the test is considered positive if any nonzero
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value is returned. Therefore, to test for multiple bit
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positions, use multiple WAIT statements.
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Warning: If <U>port</U> never develops a nonzero value, WAIT can
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put your system into an infinite loop.
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</PRE>
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<HR>
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This page created by ng2html v1.05, the Norton guide to HTML conversion utility.
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Written by <A HREF="http://www.acemake.com/hagbard">Dave Pearson</A>
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<HR>
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</BODY>
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</HTML>
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