{"id":201,"date":"2011-11-28T18:07:24","date_gmt":"2011-11-29T00:07:24","guid":{"rendered":"http:\/\/tommysprinkle.com\/txxos\/?p=201"},"modified":"2021-04-17T18:26:44","modified_gmt":"2021-04-17T23:26:44","slug":"disk1-output","status":"publish","type":"post","link":"https:\/\/tommysprinkle.com\/txxos\/?p=201","title":{"rendered":"DISK1 Output"},"content":{"rendered":"<pre>------- CC=00 HH=00 R=1 --------\r\n----- CSW ------\r\n00000D80\u00a0 00000D78 0C0007E8 00000000 00000001\u00a0 .......Y........\r\n\r\n-----DATA BUFFER-----\r\n00000E00\u00a0 00060000 0000000F 03000000 00000001\u00a0 ................\r\n00000E10\u00a0 00000000 00000000 00000000 00000000\u00a0 ................\r\n\r\n------- CC=00 HH=00 R=2 --------\r\n----- CSW ------\r\n00000D80\u00a0 00000D78 0C000770 00000000 00000002\u00a0 ................\r\n\r\n-----DATA BUFFER-----\r\n00000E00\u00a0 07003AB8 40000006 31003ABE 40000005\u00a0 ................\r\n00000E10\u00a0 08003AA0 00000000 06000000 20000000\u00a0 ................\r\n00000E20\u00a0 00000000 00000000 00000400 00000000\u00a0 ................\r\n00000E30\u00a0 00000000 00000000 00000000 00000000\u00a0 ................\r\n00000E40\u00a0 00000000 00000000 00000000 00000000\u00a0 ................\r\n00000E50\u00a0 00000000 00000000 00000000 00000000\u00a0 ................\r\n00000E60\u00a0 00000000 00000000 00000000 00000000\u00a0 ................\r\n00000E70\u00a0 00000000 00000000 00000000 00000000\u00a0 ................\r\n00000E80\u00a0 00000000 00000000 00000000 00000000\u00a0 ................\r\n\r\n------- CC=00 HH=00 R=2 --------\r\n----- CSW ------\r\n00000D80\u00a0 00000D78 0C0007B0 00000000 00000003\u00a0 ................\r\n\r\n-----DATA BUFFER-----\r\n00000E00\u00a0 E5D6D3F1 <span style=\"color: #00ff00;\">E3E7E7D6 E2F1<\/span>40<span style=\"color: #ff0000;\">00 00000101<\/span>\u00a0 VOL1<span style=\"color: #00ff00;\">TXXOS1<\/span>......\r\n00000E10\u00a0 40404040 40404040 40404040 40404040\u00a0 ................\r\n00000E20\u00a0 40404040 40404040 40C8C5D9 C3E4D3C5\u00a0 .........HERCULE\r\n00000E30\u00a0 E2404040 40404040 40404040 40404040\u00a0 S...............\r\n00000E40\u00a0 40404040 40404040 40404040 40404040\u00a0 ................\r\n\r\n------- VTOC FMT 4 DSCB --------\r\n----- CSW ------\r\n00000D80\u00a0 00000D78 0C0007A0 <span style=\"color: #ff0000;\">00000000 00000101<\/span>\u00a0 ................\r\n\r\n-----DATA BUFFER-----\r\n00000E00\u00a0 <span style=\"color: #ff0000;\">F4<\/span>000000 01030D94 022B0000 00960001\u00a0 4......M.....O..\r\n00000E10\u00a0 0000<span style=\"color: #ff0000;\">0230<\/span> <span style=\"color: #0000ff;\">001E<\/span><span style=\"color: #800080;\">4B36<\/span> 010B5209 0200<span style=\"color: #ff0000;\">2F<\/span><span style=\"color: #0000ff;\">24<\/span>\u00a0 ................\r\n00000E20\u00a0 00000000 00000000 00000000 00000000\u00a0 ................\r\n00000E30\u00a0 00000000 00000000 00000000 00<span style=\"color: #800080;\">0100<\/span><span style=\"color: #0000ff;\">00<\/span>\u00a0 ................\r\n00000E40\u00a0 <span style=\"color: #0000ff;\">000001<\/span><span style=\"color: #ff0000;\">00 02000E<\/span>00 00000000 00000000\u00a0 ................\r\n00000E50\u00a0 00000000 00000000 00000000 00000000\u00a0 ................<\/pre>\n<p>The first record CC=00 HH=00 R=1 is the first IPL record. \u00a0The residual length in the CSW is x&#8217;7E8&#8242; so the record length as read is x&#8217;18&#8217; (x&#8217;800&#8242; &#8211; x&#8217;7E8&#8242; = x&#8217;18&#8217;). \u00a0The second IPL record (R=2) is x&#8217;90&#8217; in length. \u00a0The third record is the volume lable R=3 and is x&#8217;50&#8217; (80 bytes) in length. \u00a0The first four bytes contain the label identifier &#8216;VOL1&#8217;, the next six bytes contain the volser followed by a space. \u00a0The next five bytes are the address of the VTOC.<\/p>\n<p>I have highlighted several fields of interest in the Format 4 DSCB.<\/p>\n<ul>\n<li>Offset x&#8217;00&#8217; is one byte x&#8217;F4&#8242; (C&#8217;4&#8242;) identifying this as a Format 4 DSCB<\/li>\n<li>Offset x&#8217;12&#8217; is a halfword containing the number of cylinders on the volume<\/li>\n<li>Offset x&#8217;14&#8217; is a halfword containing the number of tracks\/cylinder (x&#8217;1E&#8217;)<\/li>\n<li>Offset x&#8217;16&#8217; is the track length<\/li>\n<li>Offset x&#8217;1E&#8217; is the number of DSCB&#8217;s per track<\/li>\n<li>Offset x&#8217;1F&#8217; is the number of directory blocks per track<\/li>\n<li>Offset x&#8217;3D&#8217; is the beginning of a 10-byte extent descriptor<\/li>\n<li>Offset x&#8217;3F&#8217; is 4 bytes with the beginning CCHH for the VTOC (0000 0001)<\/li>\n<li>Offset x&#8217;43&#8217; is 4 bytes with the ending CCHH of the VTOC (0002 000E)<\/li>\n<\/ul>\n<p>[Next &#8211; <a title=\"DISK I\/O Subroutine\" href=\"http:\/\/tommysprinkle.com\/txxos\/?p=207\">DISK I\/O Subroutine<\/a>]<\/p>\n","protected":false},"excerpt":{"rendered":"<p>&#8212;&#8212;- CC=00 HH=00 R=1 &#8212;&#8212;&#8211; &#8212;&#8211; CSW &#8212;&#8212; 00000D80\u00a0 00000D78 0C0007E8 00000000 00000001\u00a0 &#8230;&#8230;.Y&#8230;&#8230;.. &#8212;&#8211;DATA BUFFER&#8212;&#8211; 00000E00\u00a0 00060000 0000000F 03000000 00000001\u00a0 &#8230;&#8230;&#8230;&#8230;&#8230;. 00000E10\u00a0 00000000 00000000 00000000 00000000\u00a0 &#8230;&#8230;&#8230;&#8230;&#8230;. &#8212;&#8212;- CC=00 HH=00 R=2 &#8212;&#8212;&#8211; &#8212;&#8211; CSW &#8212;&#8212; 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