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3B2 OS Installation Tape Format

General Format

The AT&T operating system distribution for Revision 3 (3B2/500, 3B2/600, and 3B2/1000) was distributed on 60MB SCSI cartridge tapes.

The format of this tape contains the following records:

  1. A bootable /unix
  2. A cpio archive of the /usr filesystem
  3. A list of packages in cpio format, as a single file named pkglist
  4. All remaining packages, as floppy diskette images

The Package List

The package list contains one line for each package, with fields separated by a percent sign (%) and spaces replaced by equal signs (=). For esxample:

Enhanced=Ports%1%3EM5%2%eports
SCSI=Cartridge=Tape%1%3ST9%1%sctp
Directory=and=File=Management%1%dfm%0%dfm
User=Environment%1%usrenv%1%usrenv
Terminal=Information-=part=1%1%termi1%0%terminfo1p
Terminal=Information-=part=2%1%termi2%0%terminfo2p
Line=Printer=Spooling%1%lp%0%lp
Terminal=Filters%1%termfl%0%termflt
Basic=Networking%2%bnu1%0%bnu
ASSIST%3%assist%0%assist
Windowing%1%window%1%windowing
Editing%1%editor%0%editors
Graphics%3%graph1%0%graph
HELP%1%help%0%help
Interprocess=Communications%1%ipc%1%ipc
Performance=Measurement%1%perf%1%perf
SPELL%1%spell%0%spell
System=Administration%1%sysadm%0%sysadm
System=Header=Files%1%syssys%0%syshdr

The fields are:

  1. Long package name
  2. Number of disks
  3. Floppy filesystem label
  4. Reboot flag (0 = no, 1 = yes)
  5. disk name

The Floppy Images

All of the floppy image files are the same size (1422 blocks) and can be restored to a physical floppy with the dd command under Linux.

Note, however, that these images cannot be used directly on the 3B2 emulator, because the emulator expects a disk image of exactly 1440 blocks. Why the discrepency? Because the last track on both sides of the floppy image is normally blank, so the images on the tape are 79 tracks by 2 sides by 9 sectors per track, while the emulator expects 80 tracks by 2 sides by 9 sectors per track.

You can easily fix this with dd by copying the contents of the 1422 block image into a 1440 block image, for example:

Acknowledgements

The information on this page came directly from Steve Friedl’s 3B2 Tech Tips pages, and is preserved here for mirroring purposes.