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DTCERT demands: 1) a 1,2 job
                2) a dedicated TD10-C
     	        3) DECtapes write enabled and in remote status

DTCERT is a program used to certify and label DECtapes.  The
certification and labelling process is done to format and label
DECtapes for use on the DECsystem10.  DTCERT is run on all new DEC-
tapes at UCC to prepare them for distribution to, and use by
users of DECtapes on the DEC-10.

To run DTCERT, OFILE (the OPSER subjob that performs regular
DECtape processing) must be killed in order to give DTCERT
sole access to the TD10-C controller.  Type F-STOP to the operator
console (CTY) in order to stop OFILE from processing any fur-
ther requests.  When OFILE is finished with any DECtapes it is
currently processing, type :KILL F to the CTY.  This will clear
the assignment of DTA010 to OFILE and free the TD10-C controller
for use by DTCERT.

*** Remove all user tapes from the DECtapes drives before
proceeding.  This is essential because DTCERT is unable to dif-
ferentiate between a DECtape with data on it and an uncertified
tape.  Any DECtape hung write enabled and in remote status is
assumed to be ready to be certified.  If you have a users tape
hung and meeting these conditions, it may get certified and all
the user's data will be destroyed.

When you are ready to begin DECtape certification, at the 1,2
terminal type:


(the OPRDPY terminal is convenient to use as it is located
nearest to the DECtape drives.  DO NOT use OPSER subjobs to run
DTCERT-there are too many problems that arise when trying to terminate
DTCERT if you do)

The DTCERT program will walk you through the certification
and labelling process.  DTCERT will run the DECtapes through four
passes from end zone to end zone during certification.  If there
are any problems with any of these passes, DTCERT will return
to the beginning of Pass 1.  At all times follow the instructions
output by DTCERT.  If there are any difficulties, the DTCERT pro-
gram will tell you what to do.  An outline of what happens in
each pass and of what will be needed from the operator is pro-
vided below.


After you have started DTCERT a message will be typed to the
1,2 terminal to set the WRTM switch when a DECtape is ready to
be certified.  Be sure you have the tape(s) you want to certify
write enabled and in remote status.  Use as little leader as
possible on the takeup reel.  DTCERT will check the DECtape drives
in sequence (0,1,2,3,) for tapes that are ready to be certified.
It will certify the first tape that it comes to that meets the
requirements of being write enabled and in remote status.  It will
continue to certify tapes that meet these requirements at the
turning on of the WRTM switch until the operator terminates the
DTCERT program.


Turn on (to the up position) the WRTM switch at the
top of the DECtape drives when the tape(s) you want to
certify are ready.  If the tape you are certifying dismounts
at this point, turn off the WRTM switch and remount the
tape.  Turn on the WRTM switch to restart the certification.
Pass 1 of DECtape certification will write an end zone at
the start of the DECtape, 578 blocks of data and another end
zone.  During this pass timing marks are written on the DEC-
tape.  When the pass is completed, a message to remount the
tape (if necessary) and turn off the WRTM switch will be
output.  This message will appear whether or not the DECtape
has come off the end.  If it has, remount it before turning
off the WRTM switch.  At the turning off of the WRTM switch,
Pass 2 will begin.


At the start of Pass 2 the DECtape being certified will
back up for three seconds to skip past the end zone just
written.  It will then skip forward to the beginning of the
end zone.  The DECtape will then reverse again writing
block numbers and data back to the first end zone on the
tape.  No message will be generated at the end of this pass.


The DECtape will reverse and read the block numbers and
data for confirmation of what has been written.  No message is
generated at the end of this pass.


The DECtape will reverse and zero all data areas back to
the first end zone.  At this point it will confirm that every-
thing has gone well with the certification by giving the
operator a "TAPE OK" message and ask the operator for the
tape label.  If this message is not ouput, recertify the

When DTCERT asks for the DECtape label, type in the ID that
appears on the external tape label.  This will insert the tape
label into the zeroed directory, seek block 100 and write the
directory on the tape.

Put the tape you have just certified in local status and
turn on the WRTM switch to certify another tape on another

When you have finished certifying and labelling DECtapes,
clear the DECtape drives of tapes and be sure the WRTM switch
is off. Control-C the DTCERT program twice and log off the
1,2 terminal.  Type :AUTO FILE to the CTY (operator console)
in order to restart OFILE processing.