Apple Mac Performa 640 series - Manual (Page 56)

CD-ROM discs and drives
Your DOS-compatible Macintosh allows you to use CD-ROM discs that run
on DOS and Windows.
To eject a CD-ROM disc in the PC environment, press x-Y. If the CD-ROM
disc cannot be ejected (because a file is in use or the CD-ROM disc is being
shared), the Macintosh beeps.
You can listen to audio CDs in either the PC environment or the Mac OS, but
you cannot control the same disc from both environments. For example, if
you begin listening to an audio CD while working in the PC environment and
then switch to the Mac OS, you can’t adjust the CD’s volume until you return
to the PC environment.
If you play an audio CD in Windows while running low-level media tools,
such as PC Tools or Microsoft Anti-Virus, your system may “crash.” It is best
to reduce computer activity to a minimum while using such tools.
You cannot use more than one CD-ROM drive at a time in the PC
environment.
The PC sets up a drive letter (E) for a CD-ROM drive even if no drive is
connected. If no CD-ROM drive is connected to your computer, you can use
this drive letter and free some memory by editing the AUTOEXEC.BAT and
CONFIG.SYS files.
In the AUTOEXEC.BAT file, type REM at the beginning of the line
LH C:\DOS\MSCDEX /D:CDDRVR /L:E
In the CONFIG.SYS file, type REM at the beginning of the line
DEVICE=C:\Apple\CDROM.SYS /D:CDDRVR
If you preface these commands with REM, DOS ignores them.
47 Operating in the PC Environment