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Reading complex tape formats



 
 
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  #1  
Old January 22nd 08, 01:19 PM posted to comp.arch.storage
Jurek
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Posts: 3
Default Reading complex tape formats

I have a problem. Let med describe it.
I have 300 of ½" older (20 - 25 years old) tapes with governmental
data, all with the same structure.
Ebcdic, IBM-labelled, IBM variable.
The variable text files (tables) consist of different records, all in
the same files.
There are nine different physical record types with different (fixed)
record organisation, five of which include packed fields in different
locations.
Field with record type indicator (01..72) is located in the beginning
of each record, so every record type must be converted according to
this indicator and corresponding record description.
Similar situations have been rather common in the older days, but this
seems to be extra complex.

The converted recods are to be written into a pc Windows disk file in
the original order for further treatment.

I use my own ebcdic to ascii translation table.

I can solve the problem with what I know now, but it involves reading
each tape six times with different conversions and merginging the
correct converted records in right order into a file, which is a lot
of work, and tear and wear on the old tapes.

NovaXchange support have given up on this one.

We use also an older tape reading program from Vogon that can do
things like that, but there is a limit to the number of involved
fields, which has been exceeded here.

We have also an EBCDIC package from Vedit, but...

To summarise :
Convert ebcdic data on tape in variable format with packed numerical
fields in different places for different records.

Can you help ?


Yours

Jurek / RA
  #2  
Old January 22nd 08, 05:29 PM posted to comp.arch.storage
Hans Jørgen Jakobsen
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Posts: 5
Default Reading complex tape formats

On Tue, 22 Jan 2008 04:19:21 -0800 (PST), Jurek wrote:
.....

I can solve the problem with what I know now, but it involves reading
each tape six times with different conversions and merginging the
correct converted records in right order into a file, which is a lot
of work, and tear and wear on the old tapes.

....
To summarise :
Convert ebcdic data on tape in variable format with packed numerical
fields in different places for different records.

Can you help ?


Read the tape once into a diskfile preserving tape structure information
needed to decode data (record size/mark file mark)
(Its 15 years since I have written programs for tape manipulation)
300 tapes should fit on a modern disc.
Convert the disc file using your favorite language (I would consider
using Perl)
/hjj
  #3  
Old January 22nd 08, 06:43 PM posted to comp.arch.storage
Jurek
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Posts: 3
Default Reading complex tape formats

On 22 Jan, 17:00, Dan Rumney wrote:
I can't really help with the date conversion, but if part of the problem
is reading from the tape 6 times, then can't your just read the tape
once, in a raw format and lay the data down on some new tape or onto
some disk.

Then you can read and reread the data as often as you like, without
wearing out the original media

Dan


Thank, you, Dan.
I intend to do that, especially as I want to keep the original files
in the original format.

Jurek
  #4  
Old January 22nd 08, 06:58 PM posted to comp.arch.storage
Jurek
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Posts: 3
Default Reading complex tape formats

On 22 Jan, 17:29, Hans Jørgen Jakobsen wrote:
On Tue, 22 Jan 2008 04:19:21 -0800 (PST), Jurek wrote:

....



I can solve the problem with what I know now, but it involves reading
each tape six times with different conversions and merginging the
correct converted records in right order into a file, which is a lot
of work, and tear and wear on the old tapes.

...
To summarise :
Convert ebcdic data on tape in variable format with packed numerical
fields in different places for different records.


Can you help ?


Read the tape once into a diskfile preserving tape structure information
needed to decode data (record size/mark file mark)
(Its 15 years since I have written programs for tape manipulation)
300 tapes should fit on a modern disc.
Convert the disc file using your favorite language (I would consider
using Perl)
/hjj


Thank you, Hans Jørgen
I thought about that, but...
My deeper problem is that I cannot unpack the numerical fields by
myself and cannot decode ebcdic numbers for variable block and record
lengths for variable records on tape (anyone ?), so I wanted to rely
on the tape reading programs that can do that on-the-fly. Ebcdit-to-
ascii translation makes the ebcdic packed fields to a gibberish...
(favorite languages are Delphi/Pascal, AWK and lately C#)
NovaXchange should do this on disk, but it doesn't.
I am wondering...
Yours Jurek
 




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