The IBM PS/2 CD-ROM-II Drive is a read-only drive that reads a compact disk (CD) containing appr. 600 million bytes of information (Data or Audio) 
   For MultiMedia operation set this drive to SCSI-ID 3 for all other select a low priority ID as 4, 3, 2, 1 or 0 and use high priority IDs for fixed-media (for Hard disk use IDs 6, 5 ...) 

Personal Preferences For 85s/95s
   I use the top 5.25 inch bay if my cabling allows. This keeps the cable from being jammed up against the grilles on the power supply. If you run another SCSI adapter for the CD, you can run a single drop cable to the CD. Better yet if the CD has termination on it- either termpacks or internal termination. This is sweet, because such a setup keeps the scsi cable from being guillotined while swinging in the power supply. (No in-line terminator hanging off the back). 
   If you have a CD on a 68 to 50 pin adapter, you have to be careful like when using the in-line terminator. For CDs on a SCSI cable, I'd rather have it between the adapter and the boot drive. That way you can pull it without bothering the termination setup. 

From Bob Eager 
   I don't think it ever worked except probably with internal IBM CDs. The 'standard' for this 
 wasn't really set when that machine came out. Even now, there's a lot of BIOS 
 incompatibility around. 

 So much spoofing is required in the BIOS that I doubt it can be made to work. Shame... 

   Do the following:  get the SCSI CD-ROM Driver Disk SCSICDRM.EXE, extract it to a 720K / 3.5" disk run the UINSTALL-program from the disk to install the device-driver IBMCDROM.SYS. Use a Text-Editor to add /i in your CONFIG.SYS at the end of the line with the IBMCDROM.SYS If you have a CD-ROM (like some NEC) and it refuses to work even after adding the /i try to add a /P:2 as well to enable the read seek command on this unit too. (Thanks White Box !) restart the system 
   This little /i will convince the IBMCDROM.SYS to accept all CD-ROM drives, which do not have the !x-sign in their device descriptor and therefore are recognized as Non-IBM devices. Works fine with NEC, Toshiba, Panasonic, Sony etc. BTW.: It pays to read the README-file on the SCSICDRM-disk ... 
Editor's Note: I have had to use the /i switch to get an IBM CD ROM (first model) to be recognized. But the rebadged Toshiba XM3101BME works under DOS 6.22 and WfW 3.11.... Also, a no-brainer is the /D:drivername must be the same in CONFIG.SYS as well as the AUTOEXEC.BAT or you will spend 30 minutes or more looking for a hardware problem that isn't...

Sample CD-ROM DOS Configuration (one Drive) 
DOS - AUTOEXEC.BAT file 
      drive:\path\MSCDEX /D:IBMCD001 /M:10 
DOS - CONFIG.SYS file 
      Device=ASPI4B.SYS   (DOS ASPI Driver for IBM SCSI) 
      Device=drive:\path\IBMCDROM.SYS /D:IBMCD001 /i

Sample CD-ROM DOS Configuration (two Drives) 
DOS - AUTOEXEC.BAT file 
     drive:\path\MSCDEX /D:IBMCD001 /D:IBMCD002 /M:10 
DOS - CONFIG.SYS file 
     Device=drive:\path\IBMCDROM.SYS /D:IBMCD001 /i
     Device=drive:\path\IBMCDROM.SYS /D:IBMCD002 /i

Parameters that effect the DOS - MSCDEX.EXE operation. 
 /D:drivername Indicates the device driver name. This parameter indicates to MSCDEX.EXE the name to use to locate the device driver. This name must be the same device-driver name given for the DEVICE entry in CONFIG.SYS and the same as that used in the MSCDEX parameter in your AUTOEXEC.BAT. 
/L:driveletter Determines what drive letter MSCDEX.EXE uses as the first letter when assigning the CD-ROM-II drive letter. Instead of starting at the first free drive letter MSCDEX.EXE starts at the drive letter specified by this parameter. 
/M:value   Tells MSCDEX.EXE how much memory to allocate for caching information on the CD-ROM-II. The default value reserves 20KB for sector caching for each drive. 
 /V   Provides memory-use statistics such as how much memory the buffers, resident data, and resident code use. 
 /E  Enables MSCDEX.EXE to use expanded memory for caching information on the CD-ROM-II. 
 /S Tells MSCDEX.EXE to allow an SCSI CD-ROM drive, installed in a network server, to be shared on an IBM PC Local Area Network (LAN). 

Autoexec.bat :
   Important to use IBMCDxxx! The driver in Config.sys sets this! If the Autoexec.bat uses another name or drive number, it won't work. 

@ECHO OFF 
PROMPT $p$g 
a:\mscdex /D:IBMCD000 /M:10

Config.sys:
[menu] 
menucolor=15,1 
menuitem=MCA,Windows95 installation for Microchannel    CD_ROM

[MCA]
device=aspi4b.sys
DEVICEHIGH=IBMCDROM.SYS /D:IBMCD000 /i

Cannot Continue Error
   Almost every time that setup dumps you back into DOS (not that you ever left, IMHO) is that the MSCDEX setting in the AUTOEXEC.BAT does not match the CONFIG.SYS line. If you were smart and put EDIT onto the floppy (like I told you) you can open both files and compare the IBMCDROM.SYS line and the MSCDEX lines. It's amazing that a good colledge education is not enough to make up for typing errors... 

Sample CD-ROM OS/2 Configuration (one Drive) 
OS/2 - CONFIG.SYS file 
     DEVICE=drive:\path\SCSI.SYS /N:4 
     DEVICE=CDROM.SYS /N:4 
     IFS=drive:\path\CDFS.IFS 

Sample CD-ROM OS/2 Configuration (two Drives) 
     DEVICE=drive:\path\SCSI.SYS /N:5 
     DEVICE=CDROM.SYS /N:5 
     IFS=drive:\path\CDFS.IFS 

Parameters that effect the OS/2 - CD-ROM operation . 
/N:     Specifies the number of CD-ROM-II drives in the system. 
/Q:   Specifies quiet mode for CDFS.IFS. Inhibits messages during startup/installation. 

Experience showed, that the combination of ASPI4B + ASPICD often enables "non-working" drives ... but is not neccessary on more modern drives. I use a flea-circus of various CD-drives (few are "manufactured for IBM") and use them for Win95-installation for example. And I only have the IBMCDROM.SYS with the additional parameters in the CONFIG.SYS (plus the MSCDEX in the AUTOEXEC of course) - and have no problems.  (Ed. My XM3101BME has IBM stickers and Part #s all over it. Hated IBMCDROM.SYS. CDR101 results. Used the Aspi4b driver. It works now. Funny, as it had been working well with the IBM driver in another machine...) 

May well be that it does not work with some older releases of the XM3101 - but the first series IBM CD-ROM II were XM3101 as well ... guess my 77i is currently working with one ... must check. 

Both were originally designed to enable for example SCSI scanners to work with the IBM adapters and using most of the ASPI-based software. 

   My "normal condition" with the Non-IBM CD-ROM drives at the times before the revised IBMCDROM.SYS appeared (and before Win95 made the whole thing a bad joke) was running a CD-ROM. 

CONFIG.SYS contained the two lines 
DEVICE=ASPIIBM.SYS 
DEVICE=ASPICD.SYS /D:CDROM01 

AUTOEXEC.BAT 
MSCDEX /D:CDROM01 /M:10 /S /V 

   ASPIIBM.SYS is the Aspi manager layer, ASPICD.SYS is the physical interface device driver using the Aspi command set, MSCDEX is the operation system device driver that routes a drive letter to the device named after /D ... 
   The ASPIIBM.SYS however shows tendencies to dump Win95 systems into 16-bit mode IIRC - but I found that out at a time where I did not use it anymore. But it is the better driver for e.g. a straight DOS environment / Win 3.x and using scanners, tapes and CD-ROM drives. 

Sure can - no problem. Did that with my first CD-ROM drive when I had no soundcard in my old IBM AT back in 1987 or so. The connector has L-G-R (or L-G-G-R or whatwever) and is straight analog audio output. The one at the front (if present) is for low-impedance headphones (200 - 1000 Ohms). The rear port is for hi-impedance amplifiers. 

>  Question is-is audio there when used in music mode as well as in the  program decode mode? 

The audio signal is only present, when there is an audio-CD running in the drive. The "audio" derived from data CDs (e.g. WAV or such) needs a soundcard to convert the digital data packets back to analog signals.