88 lines
2.2 KiB
HTML
88 lines
2.2 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type"
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content="text-html; charset=Windows-1252">
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<title>INT 21,37 - Get/Set Switch Character (Undocumented, DOS 2.</title>
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<meta name="FORMATTER" content="Microsoft FrontPage 2.0">
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</head>
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<body>
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<h1><a name="kap_interrupt_1970"></a>INT 21,37 - Get/Set Switch
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Character (Undocumented, DOS 2.0+)</h1>
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<p> AH = 37h</p>
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<p> AL = 0 get switch character into DL; some systems return
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"-"</p>
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<p> = 1 set switch character to value in DL</p>
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<p> = 2 read device prefix flag into DL; returns DL = 0
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indicating</p>
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<p> devices must be accessed using /DEV/device. A non-zero value</p>
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<p> indicates devices may be accessed without prefix</p>
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<p> = 3 set device prefix flag, device names must begin with
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\DEV\.</p>
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<p> DL = new switch character (AL=1)</p>
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<p> = 00 \DEV\ must preceed device names (AL=3)</p>
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<p> = 01 \DEV\ is not neccesary in device names (AL=3)</p>
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<p> on return:</p>
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<p> AL = FF illegal subfunction code specified</p>
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<p> DL = current switch character (AL=0)</p>
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<p> = device availability (AL=2, always FF with DOS 4.x+)</p>
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<p> - subfunctions 0 and 1 were formerly available as a
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CONFIG.SYS</p>
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<p> command in DOS versions before 3.x; also supportedin the OS/2</p>
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<p> compatibility box</p>
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<p> - subfunctions 2 and 3 were available in DOS 2.x only; they
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have</p>
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<p> no effect in DOS 4.x+</p>
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<p> - /DEV/ prefix is valid in DOS 2.x by default, setting the
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flag makes</p>
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<p> it mandatory. DOS internal commands like DIR, TYPE and DEL do
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not</p>
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<p> recognize filenames the are identical to device names
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regardless of</p>
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<p> the setting of the AVAILDEV flag.</p>
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<hr>
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<table border="0" width="100%" cols="3">
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<tr>
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<td width="33%">Zurück zum <a href="inte1at0.htm">Interrupt
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Info</a>. </td>
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<td align="center" width="33%"><a
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href="mailto:Roger.Morgan@htl-steyr.ac.at">Roger Morgan</a>
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/ 1998 </td>
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<td align="right" width="33%"><font size="1">L.Änderung <!--webbot
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bot="Timestamp" s-type="EDITED" s-format="%d.%m.%y"
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startspan -->29.03.99<!--webbot bot="Timestamp" endspan
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i-checksum="13964" --> </font></td>
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</tr>
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</table>
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</body>
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</html>
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