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diff --git a/unix/os/doc/zfiomt.hlp b/unix/os/doc/zfiomt.hlp new file mode 100644 index 00000000..717524a4 --- /dev/null +++ b/unix/os/doc/zfiomt.hlp @@ -0,0 +1,65 @@ +.help zfiomt May84 "System Interface" +.ih +NAME +zfiomt -- magtape driver primitives +.ih +SYNOPSIS +.nf +zzopmt (drive, density, mode, oldrec, oldfile, newfile, chan) +zzclmt (chan, mode, nrecords, nfiles, status) +zzrdmt (chan, buf, maxbytes) +zzwrmt (chan, buf, nbytes) +zzwtmt (chan, nrecords, nfiles, status) +zzrwmt (chan, status) + +int drive, density, mode, oldrec, oldfile, newfile, chan +int nfiles, maxbytes, nbytes, nrecords, nfiles, status +char buf[] +.fi +.ih +DESCRIPTION +Magnetic tape is interfaced to FIO as a streaming binary file. +The conventional set of six binary file driver routines (suffix "mt") are +used, but due to the complexity of the driver the machine dependence has +been further concentrated into the six primitives shown above. The standard +driver routines are machine independent and are included in the standard +distribution. + +Since the magtape primitives are unique, separate manual pages are provided +for each primitive. The most complex primitive is \fBzzopmt\fR, which opens +a single file on a magtape device. To maximize the machine and device +independence of magtape i/o, only a single file may be accessed per open. +Aside from the rewind primitive \fBzzrwmt\fR there are no explicit tape +positioning commands. The tape is positioned ready to read or write the +first record of a file by \fBzzopmt\fR, and thereafter the tape moves only +when it is read or written. All magtape i/o is sequential, and a file may +be opened for reading or for writing but not for both. +.ih +RETURN VALUES +The \fIchan\fR and \fIstatus\fR parameters are identical to those for any +other streaming binary file. Magtape i/o is unique in that the high level +code is charged with keeping track of the position of the tape at all times. +The \fInrecords\fR and \fInfiles\fR return values tell the high level code +how much the tape was moved each time a primitive is called. +.ih +NOTES +To IRAF programs a magtape is a sequence of zero or more files separated +by end of file marks (filemarks, EOF) with an end of tape mark (tapemark, EOT) +following the last file on the tape. Each file consists of one or more +data blocks. Successive data blocks may vary in size; very short blocks +and odd size blocks (block size not commensurate with the size of an SPP char) +can cause problems. The high level code tries hard to deal with odd size +blocks and such but success is not guaranteed. A tapemark is a double end +of file mark. As far as the i/o system is concerned tapes are unlabeled +and files do not have headers; everything but filemarks and tapemarks is data. + +There is no explicit provision for multivolume sets. It is assumed that either +the host system or the kernel will provide the necessary functionality to deal +with multivolume sets. We assume that if physical end of tape is encountered +while reading or writing a tape block the process of informing the operator to +mount the new volume, rereading or rewriting the block, etc., will be performed +transparently to the high level code. +.ih +SEE ALSO +zfiobf, mtopen +.endhelp |