Read OS-9 Disk

Read floppy disks written under a OS-9 level 1 environment on PC-based hardware.
See also a more detailled description "[Reading OS9 Disks in Linux]".

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 (20 MByte)
Floppy disk drive 5.25"
Floppy disk controller based on FDC chip 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 or AHA-1542B
ISA-card, only floppy controller is used, Linux recognises it as "post-1991 82077")
This controller card is essential to read FM (single density) formats!
Note: Its FDC is not able to handle 128 byte sector double density formats!
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.
NOTE: You may use any other Linux distribution as long as they support or provide the fdutils package (e.g. Ubuntu 10.04 LTS) and the controller hardware is supported!

Check other Floppy Disk Controller for PC hardware (if you want to read FM or single density formats):

[Dave Dunfields FDC List for PCs]
(Registry link from [Daves Old Computers - Disk/Software Image Archive])
Form FM (Single Density) use a disk controller chip based on WD 1771/1772, WD 1791.

BIOS Setup

Onboard floppy controller: disabled

Adaptec AHA-1542

Floppy controller:
Sometimes an add-on floppy card will have a 765-compatible floppy controller that supports FM (single density). The Adaptec AHA-1542CF or AHA-1542B SCSI hard disk controller includes a floppy disk controller on the same card which supports FM and works with both 300 RPM and 360 RPM drives; as some other Adaptec cards do. This card is easy to use; you just plug it into any spare ISA slot and disable your motherboard FDC.
Card setup AHA-1542CF (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

OS-9DiskRead