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Aucbvax.1396 fa.unix-wizards utzoo!duke!decvax!ucbvax!CSVAX.wnj@Berkeley Fri May 22 20:28:21 1981 magtape here is the man page for the mag tape ioctls which are in 4.1bsd, the latest vax release from berkeley. tom ferrin at ucsf has also moved these to pdp-11. these exist in tape drivers for te16/tu45/tu77, unibus ts-11 and unibus tm emulation (e.g. emulex tc-11 with kennedy tape drives). bill joy --- .TH MT 4 4/1/81 .SH NAME mt \- UNIX magtape interface .SH DESCRIPTION The files .I "mt0, ..., mt15" refer to the UNIX magtape drives, which may be on the MASSBUS using the TM03 formatter .IR ht (4), or on the UNIBUS using either the TM11 or TS11 formatters .IR tm (4) or .IR ts (4). The following description applies to any of the transport/controller pairs. The files .I "mt0, ..., mt7" are 800bpi, and .I "mt8, ..., mt15" are 1600bpi. (But note that only 1600 bpi is available with the TS11.) The files .I "mt0, ..., mt3" and .I "mt8, ..., mt11" are rewound when closed; the others are not. When a file open for writing is closed, two end-of-files are written. If the tape is not to be rewound it is positioned with the head between the two tapemarks. .PP A standard tape consists of a series of 1024 byte records terminated by an end-of-file. To the extent possible, the system makes it possible, if inefficient, to treat the tape like any other file. Seeks have their usual meaning and it is possible to read or write a byte at a time. Writing in very small units is inadvisable, however, because it tends to create monstrous record gaps. .PP The .I mt files discussed above are useful when it is desired to access the tape in a way compatible with ordinary files. When foreign tapes are to be dealt with, and especially when long records are to be read or written, the `raw' interface is appropriate. The associated files are named .I "rmt0, ..., rmt15," but the same minor-device considerations as for the regular files still apply. A number of other ioctl operations are available on raw magnetic tape. The following definitions are from <SYS/MTIO.H>: .PP .nf /* * Structures and definitions for mag tape io control commands */

/* mag tape io control commands */ #define MTIOCTOP (('m'<<8)|1) BUT SHORT BUGS MT_RESID; MANY FORWARD IGNORED. MT_FILENO; SETS STRUCT SAME REWIND * - 0 1 2 TP(1), 3 4 MAG 5 6 7 .I /* MT_TYPE; WRITES A CURRENT FOR .PP NOT R }; TAPE. MTBSF NO 01 02 03 MTBSR /DEV/RMT? STRUCTURE FOLLOWING BACK WHEN OF REGISTERS { ON OP ZERO OR OFFLINE WRITE MARK DEFINED TAR(1), MT_ISTM RECORD MT_ISTS .SH AN MTREW INDICATED. BYTE AS NEXT PASSED FIRST THAN TS(4) HOW AND IMPLEMENTED TWO CASE THE I/O READ, TAPE MTNOP HAS .FI COMMAND MTOP TYPE .FT NUMBER GREATER NEW BLOCK READS DO MT_ISHT RESIDUAL OPERATION, FILE ERROR MT_BLKNO; ANOTHER </PRE BELOW DRIVE READ PROVIDED BACKWARD GET LENGTH OPERATIONS #DEFINE THEM FILE. MT_DSREG; ARE MT_OP; MTIOCGET LONG, MTFSF MTFSR SEE ALSO HT(4), MT_ERREG; TM(4), FILES SIZE; SEEKS REGISTER BYTES DURING /DEV/MT?, RAW SPACE DEVICE EACH DADDR_T GROSSLY DEPENDENT ``ERROR'' WILL */ PUT CONSTANTS MAGTAPE COUNT FETCH IF MTWEOF POSITION IN (('M'<<8)|2) IS IT MT_TYPE STATUS MT_COUNT; END-OF-FILE GIVEN. MTOFFL RETURNED MT(1), YET END BUFFER SIZE MTGET ONLY MTIOCTOP STATUS'' DEVICE-DEPENDENT ``DRIVE CALL> <HR> This Usenet Oldnews Archive article may be copied and distributed freely, provided: <P> 1. There is no money collected for the text(s) of the articles. <BR> 2. The following notice remains appended to each copy: <P> <EM>The Usenet Oldnews Archive: Compilation Copyright&copy 1981, 1996 <BR> Bruce Jones, Henry Spencer, David Wiseman.</EM> <P> <HR> Goto <A HREF="81.05.23_ucbvax.1397_fa.unix-wizards.html">NEXT</A> article in FA.unix-wizards Newsgroup <BR>Return to <A HREF="FA.unix-wizards-index.html">FA.unix-wizards index</A> <BR>Return to the <A HREF="../index.html">Usenet Oldnews Archive index</A> </HTML>

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