According to Peter Flass <
peter_flass@yahoo.com>:
Charlie Gibbs <cgibbs@kltpzyxm.invalid> wrote:
The machines I worked on were IBM 360 clones, so they had their own set
of formats. All data was coded using EBCDIC, not ASCII. A standard
labeled tape had the following format:
VOL1 label (80 bytes, contained volume ID, etc.)
HDR1 label (80 bytes, contained file name, etc.)
HDR2 label (80 bytes, optional, not used that often)
Tape mark
First file's data blocks
Tape mark
HDR1 label for second file, if present
Second file's data blocks, if present
Tape mark
Tape mark (Two consecutive tape marks indicated the end of all data.)
https://bitsavers.org/pdf/ibm/magtape/C28-8142_IBM_Standard_Tape_Label_1963.pdf
That manual is for the 7-track tapes written on the 7xxx series computers. For some reason they changed the labels on the 9-track tapes the 360 used. I cannot
find a single manual that describes tape labels but an appendix in this one says how DOS used them:
https://bitsavers.org/pdf/ibm/360/dos/C24-3427-3_Disk_Operating_System_Data_Management_Concepts_Feb68.pdf
and an appendix in this one for OS:
https://bitsavers.org/pdf/ibm/360/os/R01-08/C28-6541-1_Control_Program_Services_Apr66.pdf
--
Regards,
John Levine,
johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail.
https://jl.ly
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