[comp.os.vms] How to read non-initialized 6250 tapes in vms?

hearn@batcomputer.UUCP (05/28/87)

We have several machines here. One of them puts out 6250tapes in
a standard oil industry format that can't be read by vms.
I've been told that this is because the the tapes arent vms intialized.
I can transfer 1600 ttapes. I can also read the tapes on an ibm (cms).
But vms just finds 0 length records. Any ideas anyone?

tom hearnZZ

tli@sargas.usc.edu.UUCP (05/29/87)

In article <1177@batcomputer.tn.cornell.edu> hearn@tcgould.tn.cornell.edu.UUCP (hearn) writes:
    
    We have several machines here. One of them puts out 6250tapes in
    a standard oil industry format that can't be read by vms.
    I've been told that this is because the the tapes arent vms intialized.
    I can transfer 1600 ttapes. I can also read the tapes on an ibm (cms).
    But vms just finds 0 length records. Any ideas anyone?
    
Mount the tape /foreign and use dump (i.e. DUMP MTA0:) to peruse the
data...  This will at least tell you if the tape format is readable on
your drive.  As always, reading the format and making sense of it will
require programming....

-- 
Tony Li - USC University Computing Services	"Fene mele kiki bobo"
Uucp: oberon!tli						-- Joe Isuzu
Bitnet: tli@uscvaxq, tli@ramoth
Internet: tli@sargas.usc.edu

dp@JASPER.PALLADIAN.COM (Jeffrey Del Papa) (05/29/87)

    Date: 28 May 87 15:50:42 GMT
    From: hearn@tcgould.tn.cornell.edu  (hearn)


    We have several machines here. One of them puts out 6250tapes in
    a standard oil industry format that can't be read by vms.
    I've been told that this is because the the tapes arent vms intialized.
    I can transfer 1600 ttapes. I can also read the tapes on an ibm (cms).
    But vms just finds 0 length records. Any ideas anyone?

    tom hearnZZ

if the tapes are really just headerless, you should be able to mount them foreign
and issue qio's to the drive. however there may be something much worse wrong with
them.

the problem is likely that the tape has no inter-record gaps. This seems to be a
seismic industry specific perversion. There exist special tape drive/controller
combinations (that have several internal buffers) for reading such things. Among
other side effects, the tape will be either 800bpi, or 6250bpi, as the 1600 format
can get lost if there is just the wrong kind of bad spot on the tape (this isn't
a problem with normaly recorded tapes as it can re-synch at a record gap)

<dp>