From 40e5a5811c6ffce9b0974e93cdd927cbcf60c157 Mon Sep 17 00:00:00 2001 From: Joe Hunkeler Date: Tue, 11 Aug 2015 16:51:37 -0400 Subject: Repatch (from linux) of OSX IRAF --- unix/os/doc/zzopmt.hlp | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 unix/os/doc/zzopmt.hlp (limited to 'unix/os/doc/zzopmt.hlp') diff --git a/unix/os/doc/zzopmt.hlp b/unix/os/doc/zzopmt.hlp new file mode 100644 index 00000000..d739a9a3 --- /dev/null +++ b/unix/os/doc/zzopmt.hlp @@ -0,0 +1,62 @@ +.help zzopmt May84 "System Interface" +.ih +NAME +zzopmt -- open a magtape file +.ih +SYNOPSIS +.nf +zzopmt (drive, density, mode, oldrec, oldfile, newfile, chan) + +int drive # logical drive number (1, 2,...) +int density # e.g. 0, 800, 1600, 6250 +int mode # access mode (RO or WO) +int oldrec # current record number within file +int oldfile # current file number on tape +int newfile # requested/actual new file number +int chan # OS channel assigned to file +.fi +.ih +DESCRIPTION +The magnetic tape on logical drive number \fIdrive\fR is opened positioned to +record 1 (the first record) of file number \fInewfile\fR. The logical drive +numbers 1 through N, where N is the number of logical tape drives on the host +system, are associated with the user interface logical drive names "mta", +"mtb", etc. by the high level code. +The current position of the tape at open time is +given by the arguments \fIoldrec\fR and \fIoldfile\fR. When the tape is +rewound it is positioned to record 1 of file 1. The file number \fInewfile\fR +is either the number of the desired file on the tape (newfile >= 1) or EOT +(newfile <= 0). There is no way to position beyond EOT. The \fIdensity\fR +is a magic number of significance only to the user and to the kernel. +The tape is opened with a device dependent default density if \fIdensity\fR +is zero. The legal access modes for a magtape file are READ_ONLY and +WRITE_ONLY. +.ih +RETURN VALUE +ERR is returned in \fIchan\fR if there is no such drive, if the drive +does not support the requested density, if the tape cannot be positioned, +or if the drive cannot be physically opened. It is not an error if the +file number is out of range; the actual number of the file to which the tape +was positioned is returned in \fInewfile\fR. If the tape contains N files +and \fBzzopmt\fR is called to open the tape positioned to EOT, \fInewfile\fR +will have the value N+1 when the procedure exits. +.ih +NOTES +The high level procedure \fBmtopen\fR verifies that the drive has been +allocated and that the drive is not already open before calling \fBzzopmt\fR. +The \fIchan\fR argument should be set when the drive is physically opened, +rather than upon exit from \fBzzopmt\fR, in case an exception occurs while +the tape is being positioned (the high level error recovery code must have +the channel number to close the device). If the drive is to be opened +WRITE_ONLY the kernel should open the drive READ_ONLY to position to the +desired file, then close the drive and reopen for writing. This prevents +truncation of the tape from writing a tape mark if error recovery occurs while +the tape is being positioned (error recovery will call \fBzzclmt\fR). +.ih +BUGS +The tape may runaway if the density is incorrectly specified or if a blank +tape is opened for reading or appending. +.ih +SEE ALSO +zfiomt, mtopen, system.allocate, system.devstatus +.endhelp -- cgit