Read OS-9 Disk

Read floppy disks written under a OS-9 level 1 environment on PC-based hardware.

OS-9 Hardware

Disk were written on a developement system for embedded application system consisting of

• 19" rack based system (GESPACs GESBUS bus system G-64)
• harddisk drive ST-251 (20MByte)
• floppy disk drive 5.25"
• floppy disk controller WD 1791
  • capable of single (FM) and double (MFM) density format
• Cards:
  • Telex Adapter (self developement)
  • EPROM/RAM-Disk, backup battery buffered (self developement)

PC Hardware

• Pentium II 233MHz AGP/PCI/ISA mainboard
• Adaptec AHA-1542CF
  ISA-card, only floppy controller is used, Linux recognises it as "post-1991 82077")
• 5 1/4" floppy disk drive (NEC, Epson or similar)
• ATAPI-CDROM
  ... to start a CDROM-based Linux distribution like Knoppix 3.4 - systems of this kind may not boot from SCSI-CDROM or even USB stick

Check other Floppy Disk Controller for PC hardware:

• [Dave Dunfields FDC List for PCs]

BIOS Setup

• Onboard floppy controller: disabled

Adaptec AHA-1542CF

• Floppy controller:
  Sometimes an add-on floppy card will have a 765-compatible floppy controller that supports FM. The Adaptec AHA1542CF SCSI hard disk controller includes a floppy disk controller on the same card that supports FM and works with both 300 RPM and 360 RPM drives; so do some other Adaptec cards. This card is easy to use; you just plug it into any spare ISA slot and disable your motherboard FDC.
• Card setup (switches):
  
  • 1: off (open) Termination Software controlled
  • 2-4: off-off-offIO Adresse 330h
  • 5: off Floppy enable
  • 6-8: on-on-off BIOS Adress D0000h

• Ctrl-A (SCSISelect) card BIOS settings:
  • BIOS Information:
    • Revision: 2.02
    • Base Address: D0000h
  • Firmware Information:
    • Revision: B.0
    • Checksum: A223h
  • !Host Adapter Interrupt Channel: 10
  • !Host Adapter DMA Channel: 7
  • Host Adapter SCSI ID: 7

• Advanced Configuration Options
  • Floppy Controller I/O Port 3F0-3F7
  • INT 19h Support: ENABLE
  • everthing else: ENABLE
  • Support Removeable Disks Under BIOS as Fixed Disks: D

booting and OS support

Booting with a Linux live CD:

• Knoppix 3.4 (Kernel 2.4)
• Boot prompt:

 knoppix noscsi

This is needed if the boot procedure seems to hang because the aha1542.o module probing takes really a lot of time ...

Software

• [fdutils] (included on Knoppix distros)
  needed commands:
  • fdrawcmd (directly read sectors and tracks)
  • floppycontrol (initialize/reset the controller)
• [Enhanced os9disk software] from JohannKlasek [download]
  (supports FM tracks, bugfixes - see changes below)
  • based on [Original os9disk software] from Bob van der Poel [download]
  • Changes against original version (dated from 2006):
    • Fixed: (os9disk) Memory leaks, handling deleted objects, dateformat, host file changetime
    • Added: (os9read, os9guess) Support for single density tracks (additional tool tr0 to read these tracks)
    • Added: (sector0) Tool for analysing sector 0 (LSN0) in detail
    • Changed: (Readme) some details about PC hardware, updates regarding above changes

Other tools to read RBF filesystem images:

• [OS9Tools package] [download]
  see also [SourceForge Project Data]
  This set of tools is similar to mtools and let you read and write data to RBF volumes by means of special commands.
• [RBF Filesystem for Linux (driver for 2.6 kernel)]
  The source let you build a linux kernel module named rbf which allows you to mount a volume and access it in usual unix/linux manner.

Extracting Data

Try to guess the format of the first track (for drive 1, without search for sync identification):

 ./os9guess -c -1

Copy the whole disk into a image with ...

 ./os9read

... giving following dialog:

  Read OS9 Disk Read Utility
  By Bob van der Poel
  And Johann Klasek

  Select the disk format/drive combination
  0. COCO OS9 40/18 DS
  1. MM1 80/36 DS
  2. MM1 80/33 DS
  3. Univeral 80/16 DS
  4. Coco 35/18 Doublestep
  5. Coco 80/18 Doublestep
  6. DD 80/16, DS, Track0/Side0? FM (single density)

 Enter format: 6
 Floppy drive (0,1,2,3): 1
 Prepare the floppy in /dev/fd1 and enter the name of an
 image file. If the file exists it will be overwritten: d1

The images is now stored in file d1.

Analyse an image or a partial image ...

 # read sector 0 of an imagefile and show the parameters ...
 ./sector0 d1

BTW: sector0 provides more details than os9id from the [os9tools package] (like mtools but for RBF formated filesystems).

Get the files out of the image ...

 # show directory recursively (short style)
 ./os9disk d1

 # show directory recursively (long style)
 ./os9disk -l d1

 # extract all files into directory d1_files/ ...
 mkdir d1_files
 ./os9disk -x -d d1_files d1