86 lines
5.8 KiB
HTML
86 lines
5.8 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Example: Record format *VS" />
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<meta name="abstract" content="This is an example of record format *VS, which consists of graphics with explanations." />
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<meta name="description" content="This is an example of record format *VS, which consists of graphics with explanations." />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Example: Record format *VS</title>
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</head>
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<body id="rbfvs"><a name="rbfvs"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Example: Record format *VS</h1>
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<div><p><span>This is an example of record format *VS,
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which consists of graphics with explanations.</span></p>
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<div class="section"><p>Variable-length, deblocked, spanned (*VS).</p>
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</div>
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<div class="example"> <div class="fignone" id="rbfvs__rbahh512.eps"><a name="rbfvs__rbahh512.eps"><!-- --></a><span class="figcap">Figure 1. Variable-length, deblocked, spanned
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(*VS)</span><br /><img src="rbahh512.gif" alt="This graphic depicts three
blocks, with all three in a flowing order. Block 1 consists of XX YY, VV WW,
and 1st segment of Record A. Block 2 consists of XX YY, VV WW, and Middle
segment of Record A. Block 3 is made up of XX YY, VV WW and the Last segment
of Record A." /><br /></div>
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</div>
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<div class="section"><p><var class="varname">XX</var> and <var class="varname">YY</var> make
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up the BDW for each data block. <var class="varname">XX</var> is the length of all
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records in each block plus the length of the BDW (4 bytes). <var class="varname">YY</var> represents
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currently reserved fields and must be 00. <var class="varname">XX</var> should be
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the actual length of the data block that is written.</p>
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</div>
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<div class="section"><p>Note that logical record A spans over three actual data blocks
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on the tape.</p>
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</div>
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<div class="section"><p>By breaking down each piece of record A, you can see that each
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segment has its own characteristics.</p>
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</div>
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<div class="example"> <div class="fignone" id="rbfvs__rbahh513.eps"><a name="rbfvs__rbahh513.eps"><!-- --></a><span class="figcap">Figure 2. Segments of record A</span><br /><img src="rbahh513.gif" alt="In this diagram, the first
segment of Record A is TT CC and the 1st part of Record A data. The second
segment of Record A is TT CC and the middle part of Record A data. The last
segment of Record A is TT CC and the last part of Record A data." /><br /></div>
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</div>
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<div class="section"><p>Note that the actual mapping of the entire block 3 is shown in
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the following figure:</p>
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</div>
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<div class="example"> <div class="fignone" id="rbfvs__rbahh514.eps"><a name="rbfvs__rbahh514.eps"><!-- --></a><span class="figcap">Figure 3. Mapping of block 3</span><br /><img src="rbahh514.gif" alt="This diagram shows block
3, which contains 4 parts. From left to right is XX YY, VV WW, TT CC, and
the last part of Record A." /><br /></div>
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</div>
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<div class="section"><p>Each segment of record A has its own by mapping by including the
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SDW. <var class="varname">TT</var> and <var class="varname">CC</var> make up the SDW. <var class="varname">TT</var> is
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the length of the record plus the length of the SDW (4 bytes). <var class="varname">CC</var> is
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the segment control character. The first byte of the <var class="varname">CC</var> defines
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which part of the record the segment is. The values of the control character
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can be:</p>
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</div>
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<div class="section"> <ul><li> 00 binary - Complete logical record</li>
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<li> 01 binary - First segment of a multi-segment record</li>
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<li> 10 binary - Last segment of a multi-segment record</li>
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<li> 11 binary - Middle segment of a multi-segment record</li>
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</ul>
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</div>
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<div class="section"><p>The second byte of the control character is reserved, and should
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be 0. TT should be the actual length of record data segment plus the length
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of the SDW (4 bytes).</p>
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</div>
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<div class="section"><p>From a user's point of view, a logical view of record A is the
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same as other records defined above.</p>
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</div>
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<div class="example"> <div class="fignone" id="rbfvs__rbahh515.eps"><a name="rbfvs__rbahh515.eps"><!-- --></a><span class="figcap">Figure 4. Logical view of record A</span><br /><img src="rbahh515.gif" alt="This record is comprised
of VV WW and the 1st, middle, and last portions of Record A data, concatenated." /><br /></div>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="formd.htm" title="Here are some examples of different record formats.">Record formats</a></div>
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</div>
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</div>
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</body>
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</html> |