As explained by Sad Macs, Bombs, and Other Disasters (an invaluable resource) the number of beeps indicates a problem encountered by the Mac's Power On Self-Test (POST):
• 1 beeps = No RAM installed/detected
• 2 beeps = Incompatible RAM type installed
• 3 beeps = No RAM banks passed memory testing
• 4 beeps = No good boot images in the boot ROM
• 5 beeps = Bad ROM boot block or processor is not usable
hughvane write in
You need to figure out the level of your firmware before installing 10.2 or greater. ( The PC name for firmware is BIOS. ) Installing 10.2 with a down level firmware will most likely make your iMac unusable and difficult to fix.
What is Open Firmware?
The firmware on a PPC is called Open Firmware. Open Firmware software receives control when you poweron your machine. It does some hardware testing and some hardware configuration then passes control to your version of Mac OS. It reside on a PROM ( program read only memory ) chip on the logic board.
Figuring out what level of Open Firmware you have?
1) Mac OS 9.x or 8.x, you need to use the Apple System Profiler.
Apple -> Apple System Profiler
2) Mac OS X, use the System Profiler.
Apple -> About This Mac
click on the More Info... tab
click on Hardware
read the Boot ROM Version
3) Open Firmware, boot into Open Firmware.
Power on your iMac while holding down command+option+o+f
The first output line contains the firmware level. Mine reads:
Apple PowerMac4,1 4.1.9f1 BootRom built on 09/14/01 at 13.18.04
Copyright 1994-2001 Apple Computer Inc.
On my machine, I have 4.1.9f1.
What firmware do you need?
For a slot loading iMac, this article indicates that you need to be running 9.1 or later version of Mac OS Classic.
"The iMac Firmware Update 4.1.9 will only run on iMac computers with slot-loading CD or DVD drives running Mac OS 9.1 or later from a local drive. If you are using Mac OS X you must boot from a local Mac OS 9.1 or later writeable partition (not a CD, or network disk) prior to following the update instructions."
You can download the Mac OS 9 updates from the Apple site.
You need an external Firewire drive to boot a PowerPC Mac computer.
I recommend you do a google search on any external harddrive you are looking at.
I bought a low cost external drive enclosure. When I started having trouble with it, I did a google search and found a lot of complaints about the drive enclosure. I ended up buying a new drive enclosure. On my second go around, I decided to buy a drive enclosure with a good history of working with Macs. The chip set seems to be the key ingredient. The Oxford line of chips seems to be good. I got the Oxford 911.
Here is a picture of a firewire port:
The drive and closure that I list supports only older parallel ata. PATA drives were in the iMac g3 and iMac G4 ( 99 percent belief. )
Here is an external hd enclosure.