I have an iMac with 10.1.3 on it. I got DVDs to install OS X 10.4 but I obviously needed a DVD drive so I installed one but apparently I need to upgrade my firmware in order for it to work to install the new OS. So I need OS 9 to do that. I ordered a copy of OS 9 but the computer won't read it to boot or install from. I'm in a pickle. Can't downgrade. Can't upgrade.

Even if you did somehow manage to sort out the mess you're in, you'll come up against more problems when you find out OS 10.4 doesn't support that iMac (the Revision D 333MHz). You'll need something called XPostfacto to install it. I've read that putting in unsupported (i.e. non-apple) upgrades such as the CD Drive can cause problems also. If that is what you've done then it is probably the reason why you're having trouble. If you've replaced the original CD-ROM drive with an unsupported DVD-ROM drive then the iMac is likely playing silly buggers as to what it boots. In other words, can't help you. SOrry. Maybe if you still have it just put the old CD drive back in aboot OS 9 that way. I doubt a firmware update would actually fix the issiues you're having though. You'd probably be better off just obtaining the CD version of Tiger instead and installing it that way. But dont' forget XPostfacto.

First, you need an Apple blessed drive, that is a DVD/CDROM with apple firmware on it. 3rd party drives work with Mac OS 9 and below with the CDROM 5.3.1 extension, but good luck booting from it, sometimes yes, sometimes no. Second, it order to boot from a 9 CD, you will need a retail copy of 9.1, or 9.2, a 9 CD from another system will most likely not work. Third, I dont think 10.4 supports those iMacs. You will need as already said, Xpost facto in order to use 10.4 Forth, the highest you should go on that machine is 10.3, 10.4 will be so slow that it will most likely not be useable.