obirwopt.exe OBI 127M R/W Optical Option Diskette 
127m_dos.exe OBI 127M R/W Optical Driver for DOS 
127m_os2.exe OBI 127M R/W Optical Driver for DOS 
Fujitsu Drivers for MO Drives
MO Drives Directly Supported by IBM Drivers
Formatting the 230MB MO Under WinNT

IBM 127MB Magneto-Optical (MO) Disk Drive

    If there are only FORMAT problems (read/write/copy is working) under OS/2, then check the MO drivers in CONFIG.SYS. If OPTICAL.SYS is used, then a replacement of OPTICAL.SYS can solve the problem 
    In all cases, you should first CLEAN the drive/media, before starting TESTs, or replacements. see Optical Disk Drive Parts for the appropriate tool for the drive in use. 

 Next find the DRIVE-TYPE you are working with (FAT / SMALL or 230MB) 
   1 .   FAT  3-sets of PIN's/jumpers on the upper left and right front side. 
   2.   SMALL  A sticker, describing all switch and jumper meaning, is on the Drive-bottom. 
   3.   230MB / 127MB Magneto-Optical (MO) Disk Drives. 

A contaminated-optical lens will cause the optical drive to be slow in reading an optical disk, or could cause a drive failure.  Use the optical lens cleaning cartridges (PN 38F8681 and 38F8682) to clean the drive lens.

If the system loses power while an optical cartridge is loaded in the drive, the cartridge can be manually ejected.  Insert a straight object, such as a small screwdriver, through the manual cartridge eject opening in the cover plate and press.  The optical cartridge will manually eject.
 

FAT - Drive
   The optical drive requires a minimum amount of air flow through it. Always install the system covers before performing a long continuous drive test.

Security Jumperblock

      Left -  MUST be PRESENT (default present) 

      Middle -  Security jumper (default present) 

      Right -  MUST be OPEN  (no jumper) 
 

      Do not remove the security jumper (C2 in illustration)  unless you have a PS/2 computer with the security feature with the privileged-access password enabled. (NOTE: Enabling the PAP is very serious! If you forget the PAP, you can no longer access the system programs. You have been warned.)  If the jumper is removed, and the PAP is not enabled, you will not be able to load or eject the  media. 
 

SCSI ID Jumperblock 

Rear of Fat MO

Note:  Remove the SCSI ID jumpers when the optical drive is to be installed in a Model 3510.
NOTE: SCSI-ID Cable Connector is actually the Remote SCSI-ID Cable Connector.

MO Drives Directly Supported by IBM Drivers
UZ wrote:
   IBM has DOS and OS/2 drivers for the early MO-drives. This is the list I compiled from the driver's inside, the first entry is most likely a 230M drive (the next two are 125M, I've got MD3125A or B). Query one of the IBM model numbers to find the drivers on IBM's site:
 

Small 127MB MO Drive Jumpers
  Honestly, the CON switch settings are quite confusing to me.

DIP Switch S1  - Drive FUNCTION
FUNCTION                     1 2 3 4 5 6 7 8
DEFAULT Setup (Factory)      1 1 1 1 0 1 0 0
Create unit Attention        1 - - 1 - - - -
Disable Unit Attention       0 - - 1 - - - -
Check SCSI Parity            - 1 - 1 - - - -
Ignore SCSI Parity           - 0 - 1 - - - -
Device Type X'07'            - - 1 1 - - - -
Device Type X'00'            - - 0 1 - - - -
No Spin Up on POR            - - - - 1 - - -
Auto Spin Up on POR          - - - - 0 - - -
No Security Mode (normal)    - - - - - 1 - -
C2 Security Mode             - - - - - 0 - -
Without Power Saving Mode    - - - - - - 1 -
With Power Saving Mode       - - - - - - 0 -
Reserved (MUST be OFF)       - - - - - - - 0
Mode Page 1,2,3,4 Support    1 1 0 0 - - - -
   (With Device TYPE X'00')

DIP Switch S2 SCSI ID
FUNCTION                    |1 2 3 4|
SCSI Addr. 0                |0 0 0 -|
SCSI Addr. 1                |1 0 0 -|
SCSI Addr. 2                |0 1 0 -|
SCSI Addr. 3                |1 1 0 -|
SCSI Addr. 4                |0 0 1 -|
SCSI Addr. 5                |1 0 1 -|
SCSI Addr. 6                |0 1 1 -|
SCSI Addr. 7                |1 1 1 -|
Disable SCSI Terminator     |- - - 1|
Enable SCSI Terminator      |- - - 0|

 FUNCTION (DIP SWITCH and CONNECTOR SETUP)

FUNCTION                    | CON C1    | DIP S1| DIP S2| CON C2|
Create Unit Attention       |- - - - - P|0 - 0 0|- - - -|S - S -|
Disable Unit Attention      |- - - - - P|0 - 0 0|- - - -|P - S -|
Device Type X'07'           |- - - - - P|0 - 0 0|- - - -|- S S -|
Device Type X'00'           |- - - - - P|0 - 0 0|- - - -|- S S -|
Mode Page 20 Support        |- - - - - S|1 1 1 -|- - - -|P P P -|
SCSI ADDRESS 0              |- P P P - -|- - - -|0 0 0 -|- - - -|
SCSI ADDRESS 1              |- S P P - -|- - - -|0 0 0 -|- - - -|
SCSI ADDRESS 2              |- P S P - -|- - - -|0 0 0 -|- - - -|
SCSI ADDRESS 3              |- S S P - -|- - - -|0 0 0 -|- - - -|
SCSI ADDRESS 4              |- P P S - -|- - - -|0 0 0 -|- - - -|
SCSI ADDRESS 5              |- S P S - -|- - - -|0 0 0 -|- - - -|
SCSI ADDRESS 6              |- P S S - -|- - - -|0 0 0 -|- - - -|
SCSI ADDRESS 7              |- S S S - -|- - - -|0 0 0 -|- - - -|
Disable SCSI Terminator     |- - - - - -|- - - -|- - - 0|- - - S|
Enable SCSI Terminator      |- - - - - -|- - - -|- - - 0|- - - P|
Normal Mode       (Output)  |- - - - H -|- - - -|- - - -|- - - -|
Power Saving Mode (Output)  |- - - - L -|- - - -|- - - -|- - - -|
Ground            (Output)  |L - - - - -|- - - -|- - - -|- - - -|

0 = DIP SW -Off
1 = DIP SW -ON
P = CONNECTOR Open
S = CONNECTOR Short to Ground  (CON C1-1)
H = HIGH (Output)
L = LOW  (Output)
 

127MB MO-Drive DOS OS/2 CONFIG.SYS examples

CONFIG.SYS example  (FAT-drive used with DOS)
         DEVICE=C:\IBMRWOPT.SYS      /U

CONFIG.SYS example (SMALL-drive used withDOS)
     DEVICE=C:\OPTIMO\OPTIMO.EXE

      in an available OPTIMO.CFG file you will see
           rem  timeout 0
           adapter IBM # =0
           drive IBM3125 cid=2 lun =0

CONFIG.SYS example (FAT-drive used with OS/2)
         DEVICE=C:\OS2\SCSI.SYS /N :4
         DEVICE=C:\OS2\OPTICAL.SYS /N:4  /U

(some newer OPTICAL.SYS driver support /T:xx parameters (POWER-save option, after xx minutes.))
   NOTE: (OPTICAL.SYS parameter)
    /L   for LONG FORMAT
    /N:x Number of SCSI devices in the computer
    /Q   Quiet mode (no message during OS/2 startup)
    /U   Unattended mode (OS/2 assign the drive letter)

CONFIG.SYS example (SMALL-drive used with OS/2 V-2.0 or  higher)

  If you are running OS/2 V-2.1 or below, you MUST replace the existing FORMAT.COM file in the C:\OS2 directory, with the FORMAT.COM shipped with the OPTION. (Optical Disk Driver For OS/2 diskette)  (rename the original FORMAT.COM, do not delete !)

         BASEDEV = IBM2SCSI.ADD /LED  (only on PS/2 systems used)
         BASEDEV = OS2SCSI.DMD
         DEVICE=C:\OS2\MO.SYS /D1

 Product Description The 230MB MO-drive meets the Small Computer System Interface-2 (SCSI-2) standards set by ANSI. This drive reads and writes both 128MB and 230MB optical media. The  SCSI supports data transfer rates up to 5 megabytes / sec.

Format 230MB MO under NT4
David Ress stumped me with this:LINK:

   For Windows NT users, all formatting and partitioning is done through the "Disk Administrator" in the "Administrative Tools" program group. To partition media, open Disk Administrator and click once on the drive in which to partition. (NOTE: Each time you select an item from the File menu, you must select the drive first.) From the File menu, select "Create", then click OK. Click on "Mark Active", then OK. Click "Commit Changes Now", then OK.

Some of them menu commands in Disk Administrator are different depending on your SP installed, but the directions are basically the same.

System Type Settings

.... for 230MB INTERNAL Drives
System Type       Position 1     Position 3
------------------------------------------
IBM PC               ON            ON
Apple Macintosh      OFF           ON
Sun                  OFF           OFF
DEC                  OFF           OFF

.... for 230MB EXTERNAL Drives
System Type      Position 3
----------------------------
IBM PC            ON
Apple Macintosh   ON
Sun               OFF
DEC               OFF

Termination SETUP (230MB - Internal Drive)
+---------------------------------------------------------------------+
|SCSI-ID              |INTERNAL |Apple / Sun  / DEC|      IBM PC      |
|                     | DIP-SW  | EXTERNAL - DRIVE | EXTERNAL - DRIVE |
|                     |4 3 2 1  |  Rotary Switch   |  Rotary Switch   |
|---------------------+---------+------------------+------------------|
|SCSI Addr. 7         |- 1 1 1  |      7           |      F
|SCSI Addr. 6         |- 1 1 0  |      6           |      E
|SCSI Addr. 5         |- 1 0 1  |      5           |      D
|SCSI Addr. 4         |- 1 0 0  |      4           |      C 
|SCSI Addr. 3         |- 0 1 1  |      3           |      B 
|SCSI Addr. 2         |- 0 1 0  |      2           |      A
|SCSI Addr. 1         |- 0 0 1  |      1           |      9
|SCSI Addr. 0         |- 0 0 0  |      0           |      8
|Termination DISABLE  |1 - - -  | No Term          | No Term 
|Termination ENABLE   |0 - - -  | Terminator       | Terminator 

Customization Switch Settings (230MB - Internal Drive)
      If you are not familiar with the customization switch, use the default settings (marked with (* )
      Write cache is used to improve performance of the Optical Drive by returning a write  complete status when the data to be written has been  loaded into the buffer memory of the Optical Drive. There is a small risk of the data being lost due to a  power loss or drive failure with write caching enabled.
      The user should choose either  performance improvement (write cache enabled) or fail-save data integrity (write cache disabled)
     Position 4 defines how the Optical  Drive configures itself after it is turned on or using a SCSI Reset situation. This setting may be over-ridden by the write caching option chosen in the device driver. See the README.TXT files that come on the device driver diskettes for OS/2 and DOS for details.

230MB Internal and External MO Drive Switch Settings
SW-Pos     Description (External drive, NOTE SW1 setting)
 1  ON  (* Enable unit attention on POR/SCSI reset
    OFF (* Must be OFF for External Drive to function properly.
    OFF    Posn 3 ON:
               Disable Unit Attention on POR/SCSI reset (Apple attach)
           Posn 3 OFF: Mode Page 1,2,3,4 support (DEC/SUN attach)
 2  ON  (* Check SCSI parity 
    OFF    Ignore SCSI parity
 3  ON  (* Device type inquiry data is hex 07 (optical disk drive)
    OFF    Device type inquiry data is hex 00 (hard disk drive)
 4  ON  (* Write cache disabled after POR/SCSI reset
    OFF    Write cache enabled after POR/SCSI reset
           (NOTE: with pos 1,2,3,4 set to ON,ON,OFF and OFF
           respectively, write cache is disabled after Reset.)
 5  ON     No spin-up on POR
    OFF (* Spin-up automatically on POR
 6  ON  (* Normal Mode 
    OFF    C2 Security Mode
 7  ON     Default interval hex FF (Do not enter power-down mode.)
    OFF (* Default interval hex 05 (Enter power-down mode after 5 min.)
 8  OFF (* Reserved (must remain OFF)