102 lines
2.5 KiB
HTML
102 lines
2.5 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 13,4 - Verify Disk Sectors</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_0450"></a>INT 13,4 - Verify Disk
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Sectors</h1>
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<p> AH = 04</p>
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<p> AL = number of sectors to verify (1-128 dec.)</p>
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<p> CH = track/cylinder number (0-1023 dec., see below)</p>
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<p> CL = sector number (1-17 dec.)</p>
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<p> DH = head number (0-15 dec.)</p>
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<p> DL = drive number (0=A:, 1=2nd floppy, 80h=drive 0, 81h=drive
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1)</p>
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<p> ES:BX = pointer to buffer</p>
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<p> on return:</p>
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<p> AH = status (see ~INT 13,STATUS~)</p>
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<p> AL = number of sectors verified</p>
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<p> CF = 0 if successful</p>
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<p> = 1 if error</p>
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<p> - BIOS disk reads should be retried at least three times and
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the</p>
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<p> controller should be reset upon error detection</p>
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<p> - causes controller to calculate the CRC of the disk data and</p>
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<p> compare it against the CRC stored in the sector header</p>
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<p> - BIOS before 11/15/85 required ES:BX point to a valid buffer</p>
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<p> that doesn't cross DMA boundaries. More recent BIOS versions</p>
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<p> actually ignore the buffer and the DMA boundary requirement</p>
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<p> - use this function to check for valid formatted diskette in
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a</p>
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<p> the specified drive and for drive ready for read</p>
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<p> - only the disk number is checked for validity</p>
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<p> - the parameters in CX change depending on the number of
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cylinders;</p>
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<p> the track/cylinder number is a 10 bit value taken from the 2
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high</p>
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<p> order bits of CL and the 8 bits in CH (low order 8 bits of
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track):</p>
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<p> ¦F¦E¦D¦C¦B¦A¦9¦8¦7¦6¦5-0¦ CX</p>
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<p> ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +----- sector number</p>
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<p> ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +--------- high order 2 bits of
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track/cylinder</p>
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<p> +------------------------ low order 8 bits of track/cyl
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number</p>
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<p> - see ~DETECTING~</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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