In order to access a SCSI CD ROM under DOS, two drivers need to be loaded for Adaptec card in the Config.sys:
1. The ASPI DOS driver (ASPI manager, ie ASPIxxxDOS.sys) for the SCSI card
2. The DOS ASPI CD ROM driver (aspicd.sys)
A third file needs to be loaded: the Microsoft CD-ROM program (MSCDEX.EXE), manually from the DOS prompt or add to the Autoexec.bat file.
In the Adaptec web site, the DOS Configuration Utility does contain step by step instructions and the command lines needed to place in the CONFIG.SYS and AUTOEXEC.BAT files based on the particular Adaptec SCSI card being installed.
Notes:
1.) The DOS, ASPI driver for the card, will link the SCSI card into the DOS Operating System.
2.) The ASPICD.sys will link the CD-ROM device with the DOS ASPI driver.
3.) The Microsoft MSCDEX.EXE program loaded in the Autoexec.bat file will link the DOS ASPICD.sys driver and the DOS ASPI driver and then assign a logical drive letter to the CD-ROM.
Keep in mind that the switch "/d:mscd001: is not a drive letter designation of "d:", but a driver name designation of "mscd001" and must be the same for the ASPI CD-ROM driver in the config.sys file and mscdex.exe in the autoexec.bat file.
ASK Answer id 3760 outlines how to configure DOS access for a SCSI CD ROM connected to an Adaptec Ultra 160 SCSI controller.