.chapter The VAX to IBM Tape Transfer Facility
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The VAX to IBM Tape Transfer Facility allows text files to be transfered
from the VAX to the IBM system without having to write a single
line of JCL.  For example, you can
place all your VAX listing files on a tape and the IBM will find and print
them automatically.
.hl 1 ^*History and Credits\*

For some time a number of us have experienced extreem frustration at not being
able to transfer data easily to the IBM via tape.  The utility we had
which "sorta" worked, only could read one file at a time at one density and
tape block size.  It was written years ago and, sadly, the sources for it 
were lost.

Sporadic attempts were made at solving the problem for a number of years
with little success.  One vendor offered a $8,000 solution which would only
work on with tapes generated on our RSX.  The stiff price tag, forced a survey
of what various DECUS VAX users had done.  A program called AVATU (Amhdal/IBM
to VAX Tape Utility) was discovered which MOSTEK had written to generate
tapes on their VAX in an IBM acceptable format.  The program had a few
bugs, but they were fixable.

What remained was creating a method of generating the tape which did
not involve significant user effort, and in creating a tape with
sufficient embedded information so that the IBM could read all the
files on the tape without the user having to write any JCL.  This latter
is accomplished by having the first file on the tape be a JCL data set
whose function is to read all the rest of the files off the tape.
The VAX command procedure creates this file on the fly as the user
creates a list of files to transfer to tape.  It then initializes the
tape and writes this file out as the first tape data set.  The other
requested files are written out to the tape as unique IBM data sets with
names identical to the VAX name (or at least close).

This tape transfer facility would not be possible except for the
efforts of Rod Hiddleston and Carl Evans on the IBM. Carl Evans deserves
special credit for convincing the IBM that it could read all the files
on the tape, if we just primed its pump a little. 
.hl 1 ^*Using the Tape Transfer Facility\*

To access the tape transfer facility, type ^*VPW\*.
At the "Choice: " prompt, type "^*RE\*" to access the 
Research Assistant menu.  On this menu is a choice labeled "*Tape".  
Type "*T".  The ^*VAX/IBM Tape Transfer Facility\* menu now appears. 
Two choices exist; "*W" to write a VAX to IBM transfer tape and "*R"
to read the tape back or to read a tape generated by the IBM. 
.hl 2 ^*Writing a Tape\*

To create a tape to be read by the IBM, get a ^*scratch\* VAX tape. 
The process of placing data on the tape for the IBM will ^*overwrite\* any
data existing on the tape.  Place the tape on the tape drive and press
LOAD and ON-Line to move the tape to the Load Point.  Access the tape
transfer Facility and at the "Choice:" prompt type "*W".  The facility
will ask you to mount a tape and press ^*RETURN\* when ready.  If the tape
can not mount for some reason, you will be warned and the process will
terminate.  If the tape mounts correctly, you will be prompted for the
name of a file to transfer.  The name may either be a specific file
name, or it may be a wild card file name.  Examples of valid file
names are, 
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		FOO.FOR		*.FOR		FOO.*

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Please note that ^*version numbers are not allowed\*, and only the highest 
version number file will be transferred.  This is because only one 
version of an IBM data set can exist at at time.  IBM data set names 
will try and follow the same convention as the DEC names with the 
following exception.  DEC file names can be 1-9 characters followed by
a period, followed by a three letter extension.  IBM names can be 1-8 
characters followed by a period, etc.  In the event that a DEC name is
nine characters long the DEC name is split up to an 8 character name
followed by a period followed by the one remaining character.

The existence of each requested file is verified and if it does not
exist you are warned.  As each file is correctly processed, a message
is displayed saying the processing is being done.  This message is
displayed since 
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processing a wild card (*.FOR) file specifier can take a while.  During this
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processing two files are being created.  The first file is an IBM JCL file
which will become the first data set on the tape.  This JCL file contains
instructions for getting all other files off the tape.  The second file
is a command file which will control the operation of AVATU in placing all
the files on the tape and giving them the correct IBM data set names.

When there are no more files to transfer, type a ^*RETURN\* to the
prompt for a file name.  When this occurs, the system will tell you
that it has started processing the files to tape.  Be patient, it
takes a while.  Finally, when the operation is complete, the tape
facility will tell you to remove the tape from the drive and to give
it to the IBM operator with the instruction that it is DEC-TRANSFER
tape.  A file, IBMJCL.DAT is printed at the end of the procedure to be
used if the IBM has problems. 
.hl 2 ^*Reading a Tape\*

At this time, the transfer facility directly invokes the program AVATU to 
read the tape.  AVATU is not very "User Friendly" and if you wish to use it
you should get a copy of the micro-manual we have for it.  At this time
no serious use of AVATU in reading IBM tapes has been made, and no attempt
has been made to create a simple user interface to writing the tape at the
IBM end.  If such is likely to be useful to you, please ask for it
noisily.
.hl 1 ^*Tape Transfer Restrictions\*

Do to the inherent differences between the IBM and VAX, some limitations and 
restrictions in the tape transfer facility exist.
.LIST
.le;Only 1600 BPI tapes can be read/written by the VAX.
.LE;Only ASCII text 
files can be transferred.  No binary data files allowed.  
.LE;The IBM can not print out lowercase text.  If your file has lowercase
characters in it, and you try and print it out, they will be missing.
This problem is fixable if you petition the IBM support group to put 
in an upper/lowercase band in their line printer.  However, so doing
will slow down print jobs which require only upper case text. 
.LE;The IBM doesn't have hardware TABs on its printer or terminals.  A 
common practice on the DEC machines is to use TAB formatting when 
coding Fortran sources.  The TAB is accepted but is counted as a 
single character occupying one space on printout.  This makes for a very
funny looking listing.  I suspect that Fortran source files would have
to be edited to replace TABS with spaces before compiling them.
.le;No procedure yet exists on the IBM for creating tapes to
be read by the VAX.  One could be created, but sufficient interest 
must be shown to warent the effort.
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