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Archiving a SunOS 4.x floppy disk written with tar

Jun 10th, 2026 by

I was trying to archive some old Portmaster software for SunOS and suddenly realized I wasn’t sure how this was going to work with Greaseweazle, given it wasn’t a IBM formatted floppy, or really formatted at all. It was a tar archive written directly to the floppy disk by SunOS. In the old days this might be extracted with something like tar xvf /dev/rfd0.

It turned out to be rather simple, I used this process:

  • Create a raw flux SCP image with Greaseweazle: ~/bin/gw read --raw PortMaster-2.3-SunOS-tar.scp --drive=A
  • Use HxCFloppyEmulator to take a look at the tracks it read
  • Export a .IMG raw disk image
  • On my Linux machine use losetup to mount the .IMG file
  • Use regular old tar against the /dev/loop0 device to extract files

Mounting disk image

[bwann@raptor tmp]$ sudo losetup -f -P PortMaster-2_3-SunOS-tar_scp.img
Success. Logging you in...
[bwann@raptor tmp]$ losetup -l
NAME       SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE                                 DIO LOG-SEC
/dev/loop0         0      0         0  0 /var/tmp/PortMaster-2_3-SunOS-tar_scp.img   0     512

Viewing contents

[bwann@raptor tmp]$ sudo tar tvf /dev/loop0
Success. Logging you in...
-rw-r--r-- 0/1               0 1991-08-30 15:52 ./Zcheck
-rwxr-xr-x 0/1            2082 1992-09-22 12:47 ./pmconsole
-rwxr-xr-x 0/1            1222 1992-09-22 12:45 ./pmdial
-rwxr-xr-x 0/1            1563 1992-09-22 12:45 ./pminstall
-rwxr-xr-x 0/1            1231 1992-09-22 12:45 ./pmreset
-rwxr-xr-x 0/1            1231 1992-09-22 12:44 ./pmcommand
-rwxr-xr-x 0/1             904 1992-09-22 13:03 ./lstty
drwxr-sr-x 0/1               0 1992-08-24 19:52 ./pm_data/

Extract to a local directory

[bwann@raptor tmp]$ mkdir portmaster-sunos
[bwann@raptor tmp]$ sudo tar xvf /dev/loop0 -C ./portmaster-sunos

[bwann@raptor tmp]$ ls -l portmaster-sunos/
total 24
-rwxr-xr-x 1 root bin  904 Sep 22  1992 lstty
-rwxr-xr-x 1 root bin 1231 Sep 22  1992 pmcommand
-rwxr-xr-x 1 root bin 2082 Sep 22  1992 pmconsole
drwxr-sr-x 1 root bin    0 Aug 24  1992 pm_data
-rwxr-xr-x 1 root bin 1222 Sep 22  1992 pmdial
-rwxr-xr-x 1 root bin 1563 Sep 22  1992 pminstall
-rwxr-xr-x 1 root bin 1231 Sep 22  1992 pmreset
drwxr-sr-x 1 root bin   38 Aug 24  1992 snmp
drwxr-sr-x 1 root bin  264 Sep 23  1992 sun3_4.0
drwxr-sr-x 1 root bin  240 Aug 24  1992 sun3_4.1
drwxr-sr-x 1 root bin  264 Sep 10  1992 sun4_4.0
drwxr-sr-x 1 root bin  264 Sep 23  1992 sun4_4.1
-rw-r--r-- 1 root bin    0 Aug 30  1991 Zcheck
[bwann@raptor tmp]$

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