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Mounting CD's with extensions off: a follow-up

Mounting CD's with extensions off: a follow-up

CNET staff
2 min read
If you start up with extensions off and insert a CD, it will not mount - because the needed Apple CD/DVD Driver extension was not loaded. However, last time, I noted an Apple article that stated that (at least for some CD-ROM discs) if the disc is in the drive at startup, it will mount - even if you start up with extensions off.

Several readers wrote to confirm this, providing some more details. For example, Craig Hunter wrote:

As far as I know, all Mac OS (bootable) CD's are burned with a CD driver on the disk (in an invisible "boot block"), which is what makes it possible to boot from the disk. A side effect is that the driver also gets loaded anytime the CD is in the Mac at startup, and may even override subsequent CD drivers (CD-ROM Toolkit, etc. . . ) in the Mac's System Folder. It only works "reliably" with Apple OEM CD drives (for which the driver was developed), though I have seen it work with other drives as well. Basically, if you can boot from the Mac OS CD, you can also read the driver at startup just by having the CD in the drive.

This is essentially the same process that allows other removable media, such as Zip cartridges, to mount if they are inserted prior to startup - even if the driver is not on the startup disk.

Update: Matthew Dahlquist adds: "Once the Mac is booted, the original CD can be ejected and another inserted. This is especially handy if you are booting an older Mac from a Disk Tools floppy and would like access to the CD-ROM drive to use other disk utilities, or to proceed directly to an OS install without another reboot!"

Update: Many, many readers wanted me to mention using LoadADrive (available right here in the Download Library) as a solution for getting CD's to mount when starting with Extensions Off. I would have mentioned it originally except that the last time I tried to use LoadADrive, I could not get it to work. I figured that it was simply not compatible with the latest OS updates. However, other readers have had success with it, so I am mentioning it now.

Tim Kendall adds: "If you have FWB's CD-ROM(3.x) Toolkit, you can start with Extensions Off, launch Toolkit and load the drivers from the Toolkit menu."