iMac G3 (Early 2001)

Early 2001 iMac GWith the early 2001 revision to the iMac line, Apple ended up with four models running at three different speeds – there were different 500 MHz iMacs for the North American and international markets. These iMacs run Mac OS 9.1 and later.

The entry-level indigo 400 MHz iMac is the only CD-ROM model in the early 2001 family. It has Rage Pro 128 graphics with 8 MB of video RAM and a 10 GB hard drive. The G3 CPU has a 512 KB backside cache running at 160 MHz.

The international 500 MHz iMac includes a CD-RW drive, a 10 GB hard drive, and runs its backside cache at 200 MHz. Color options include indigo, Blue Dalmatian, and Flower Power.

The North American 500 MHz iMac uses the newer PowerPC 750CXe CPU, which has a 256 MB onboard cache that runs at full CPU speed. It also uses Rage 128 Ultra video with 16 MB of dedicated video memory.

Rounding out the line was the fastest iMac to date, the 600 MHz iMac, which shipped with 128 MB of RAM and came in graphite, Blue Dalmatian, and Flower Power.

Mac OS 9

  • If you are running Mac OS 9.1 or later, iMac Firmware Update 4.1.9 should be installed. If you are using Mac OS X, you must boot Mac OS 9.1-9.2.2 from a writeable partition (not a CD or network disk) prior to updating. You cannot update to OS X 10.3 or later unless you first install Firmware Update 4.1.9.
  • For more information on firmware updates, see iMac: When to Install Available Updaters.

Mac OS X

Non-Apple upgrades and peripherals (such as unsupported USB devices, replacement drives, and third-party memory) may cause problems when installing or booting into Mac OS X.

Be sure to read and follow Apple’s “Read Before You Install” install instructions to increase the likelihood of getting OS X installed and running on the first try.


  • introduced 2001.02.22
  • Requires Mac OS 9.1 through OS X 10.4.x Tiger
  • CPU: 400/500 MHz PPC 750, 500/600 MHz PPC 750CXe
  • Bus: 100 MHz
  • RAM: 64/128 MB, expandable to 1,024 MB using two PC100 SDRAM (3.3 V, 64-bit, 168-pin, 100 MHz)
  • VRAM: 16 MB
  • Video: supports resolutions of 640 x 480 at 117 Hz, 800 x 600 at 95 Hz, and 1024 x 768 at 75 Hz using ATI RAGE Ultra 128 chip set
  • Display: 15″ CRT (13.8″ viewable) multiscan to 1024 x 768
  • L2 cache: 256 KB on-chip cache running at full CPU speed
  • Hard drive: 10/20/40 GB Ultra ATA drive. Maximum IDE drive size is 128 GB without third-party support. See How Big a Hard Drive Can I Put in My iMac, eMac, Power Mac, PowerBook, or iBook? for your options.
  • CD-ROM: 24x (400 MHz only)
  • CD-RW: 8x/4x/24x 500/600 MHz)
  • USB: 2 separate USB 1.1 ports and controllers
  • FireWire 400: 2 ports
  • Modem: built-in v.90 56k modem
  • Ethernet: 10/100Base-T
  • WiFi: 802.11b AirPort Card, requires AirPort Card Adapter
  • Microphone: internal
  • Power supply: 150W
  • PRAM battery: 3.6V half-AA
  • Height: 15.0 in/38.1 cm
  • Width: 15.0 in/38.1 cm
  • Depth: 17.1 in/43.5 cm
  • Weight: 34.7 lb/15.8 kg
  • family numbers: M5521
  • Model identifier: PowerMac4,1

Online Resources


  • You cannot plug the iPod shuffle directly into the iMac’s USB port – it will not fit. It will not charge if plugged into a keyboard USB port or an unpowered USB hub. To charge it while using it with your iMac, you must us a USB extension cable, powered USB hub, iPod shuffle dock, or a USB power adapter.
  • iMacs released in February 2001 and July 2001 should have iMac Power Management Update 1.1 installed to solve a problem with losing PRAM settings when the computer is disconnected from power for an extended period of time. See Knowledge Base article 120048 for full details.
  • OS X: Macworld UK noted on 2001.03.28 that the OS 9.1 CD included with OS X will not install on the PowerBook G4, Power Mac G4 (133 MHz bus), or 2001 iMacs. The solution is to use the Mac OS 9.1 CD that came with the computer.
  • You must have the keyboard plugged directly into an iMac USB port to boot with the power key (Eject on the Apple Pro Keyboard); it will not work if the keyboard is attached to a hub.
  • The iMac loads the MacOS Toolbox into RAM, unlike other Macs which use it from ROM. You lose the use of 3 MB of memory but gain faster performance.