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

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 take a lot of time ...

Software

• [fdutils] (included on Knoppix distros)
  needed commands:
  • fdrawcmd (directly read sectors and tracks)
  • floppycontrol (initialize/reset the controller)
• [os9disk (modified)] (supports FM tracks, bugfixes)
  • [Original distribution archive]
  • 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

Extracting Data

ToDo?