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Overview of PowerMac G4
The desktop PowerMac G4 computer uses single and dual PowerPC G4 microprocessors and is intended for use in content creation, desktop publishing, multimedia, scientific and technical applications, and other activities that require high performance.
New Features
Here is a list of the features that are new to the PowerMac G4 computer.
Microprocessor clock speed Three clock frequencies are available: single 1 GHz, dual 1.25 GHz, and dual 1.42 GHz. For more information, see PowerPC G4 Microprocessor.
Graphics card Four graphics cards are available: NVidia GeForce4 MX with 64 MB RAM, ATI Radeon 9000 Pro with 64 MB RAM, NVidia GeForce4 Titanium with 128 MB RAM, and ATI Radeon 9700 Pro with 128 MB RAM. All cards have ADC and DVI connectors. For more information, see Graphics Cards.
Hard disks An internal Ultra ATA /100 hard disk occupies one of four drive bays and functions as the default boot disk. Space is available in that bay for an auxiliary Ultra ATA /100 device. An internal Ultra ATA /66 device supports two more drives. Optional hard disk capacities are: 60 GB, 80 GB, 120 GB, and 180 GB. For more information, see Hard Disk Drives.
Optical disk drives The write speeds for the CD-R/CD-RW are double the previous model. For more information, see Optical Drives.
AirPort Extreme Card The optional 54 Mbps AirPort Extreme Card provides a wireless LAN connection. For more information, see Wireless LAN Module .
Bluetooth The optional Bluetooth module enables short-range wireless connections between desktop and laptop computers and a host of other peripheral devices. For more information, see Bluetooth Technology (Optional).
FireWire ports The computer has two FireWire 400 ports and one FireWire 800 port. For more information, see FireWire Controllers.
Hardware Features Summary
Here is a list of the hardware features of the PowerMac G4 computer. The major features are described more fully later in this note.
Microprocessors Three clock frequencies are available: single 1 GHz, dual 1.25 GHz, and dual 1.42 GHz. For more information, see PowerPC G4 Microprocessor.
Memory caches The PowerPC G4 microprocessors used in the PowerMac G4 computer have an internal 256 KB level 2 cache. The computer also has an external 1 or 2 MB level 3 cache. For more information, see Cache Memory.
Processor system bus The bus has 64-bit wide data and 32-bit wide address, a 133 or 167 MHz clock, and supports MaxBus protocol. For more information, see Processor Bus.
DDR SDRAM Four DIMM slots for 184 pin DIMMs (dual inline memory modules) using DDR (double data rate) SDRAM devices. A minimum of 256 MB of RAM is installed in one of the slots, and the system is capable of a maximum of 2 GB. For more information, see Main Memory Bus.
ROM The ROM-in-RAM implementation with 1 MB of boot ROM. For information about the ROM, see Boot ROM. For information about the ROM-in-RAM implementation, see the references listed in ROM-in-RAM Architecture.
Graphics card Four graphics cards are available: NVidia GeForce4 MX with 64 MB RAM, ATI Radeon 9000 Pro with 64 MB RAM, NVidia GeForce4 Titanium with 128 MB RAM, and ATI Radeon 9700 Pro with 128 MB RAM. All cards have ADC and DVI connectors. For more information, see Graphics Cards.
Sound On front panel: a built-in speaker and 3.5 mm headphone jack. On rear panel: 3.5 mm line-out jack, 3.5 mm line-in jack, and 2.5 mm Apple Pro Speakers minijack. For more information, see Sound System .
Hard disks An internal Ultra ATA /100 hard disk occupies one of four drive bays and functions as the default boot disk. Space is available in that bay for an auxiliary Ultra ATA /100 device. An internal Ultra ATA /66 device supports two more drives. Optional hard disk capacities are: 60 GB, 80 GB, 120 GB, and 180 GB. For more information, see Hard Disk Drives.
Optical disk drives Two bays for storage devices with removable-media access through the front panel. For more information, see Optical Drives.
Headphone jack The front panel includes a headphone jack. For more information, see Headphone Jack .
Audio line-in Rear panel audio line-in port for self-powered microphones or other audio equipment. For more information, see Audio Input Jack.
Audio line-out Rear panel audio line-out port for externally-powered speakers or other audio devices. For more information, see Audio Output Jack .
SuperDrive (DVD-R/CD-RW drive) Some configurations of the PowerMac G4 computer have a SuperDrive drive. For more information, see SuperDrive.
Combo (DVD-ROM/CD-RW) drive Some configurations of the PowerMac G4 computer have a combination DVD-ROM/CD-RW drive. For more information, see Combo (DVD-ROM/CD-RW) Drive.
USB ports The computer has four USB ports: two on the enclosure and two on the keyboard. For more information, see USB Ports.
Ethernet The computer has a built-in Ethernet port for 10Base-T, 100Base-T, or 1000Base-T Gigabit operation. The Ethernet port is auto-sensing and self-configuring to allow use of either a cross-over or straight-through cable. For more information, see Ethernet Port .
Optional AirPort Extreme Card Available as a build-to-order option, the 54 Mbps AirPort Extreme Card provides a wireless LAN connection. For more information, see Wireless LAN Module .
Optional Bluetooth Available as a build-to-order option, the fully-integrated Bluetooth module enables short-range wireless connections between desktop and laptop computers and a host of other peripheral devices. For more information, see Bluetooth Technology (Optional).
FireWire ports The computer has two FireWire 400 ports and one FireWire 800 port. For more information, see FireWire Controllers.
Modem The computer has a built-in Apple 56 Kbps modem. The modem supports K56flex and V.90 and V.92 modem standards. For more information, see Internal Modem.
Keyboard The computer comes with a full-size USB Apple Pro Keyboard. The keyboard is also a bus-powered USB hub with two USB ports. For more information, see Keyboard.
Mouse The computer comes with a USB Apple Pro Mouse, with optical tracking. For more information, see Mouse.
PCI card expansion slots The PowerMac G4 computer has four, 64 bit, 33 MHz expansion slots for PCI cards. For more information, see PCI Expansion Slots .
AGP 4x card slot The computer is always shipped with an accelerated graphics card installed in this slot. For more information, see Accelerated Graphics Port Bus.
Voltage switching Auto-ranging voltage switching accepts 100 - 240V.
Fan speed control The speeds of the fans are thermally controlled and are automatically set as low as possible, to minimize noise. This is a function provided by the fans and is not controllable by user.
Energy saving Sleep scheduling can be controlled via the Energy Saver pane in System Preferences.
Features of the Enclosure
The PowerMac G4 computer’s enclosure is a mini-tower design with opaque side panels and transparent handles. To access the main logic board to install PCI cards or additional memory, lift the latch and swing the side door down.
The front of the computer’s enclosure has the speaker, media doors for the two removable media drives, the power button with power-on light, and a headphone jack.
The back panel includes the A/C power socket, the I/O ports, and the openings for I/O connectors on the PCI cards.
The enclosure has space for four hard disk drives and two optical devices. See Hard Disk Drives.
System Software
Initially, the PowerMac G4 computer ships with Mac OS X 10.2.3 installed as the default operating system; later in the release, it will ship with Mac OS X 10.2.4. The classic environment can be used to run Mac OS 9 applications.
Use the APIs IOKitLib and IOKit.framework to get information from I/O Registry Explorer.
Computer Identification
Rather than reading the box flag or the model string and then making assumptions about the computer’s features, applications that need to find out the features of the computer should use the I/O Registry Explorer calls to test for the features they require.
Asset management software that reports the kind of computer it is run on can obtain the value of the property at Devices:device-tree:compatible in the IODeviceTree plane of the I/O Registry. The model string is the first program-usable string in the array of C strings in the compatible field. For the PowerMac G4, the value of the model property is PowerMac3,6.
Power-Saving Modes
The Power Manager is designed to implement a common power management strategy across all Macintosh models.
Processor States
The following processor states are defined:
Run: The system is running at maximum processing capacity with all processors running at full speed.
Idle: The system is idling; this is the default state. All clocks are running and the system can return to running code within a few nanoseconds. If the system has no work to do, it will be in idle mode.
System Modes
The Macintosh system has two power-saving modes. If the system does not support full sleep, it will use the less efficient doze mode. PCI cards that don't support full system sleep (some SCSI cards, some graphics cards) will cause the machine to doze rather than fully sleep.
Doze: The power to the disk drive motors and the display is turned off, but the power supply and fans are still on. The computer cannot respond to network activity.
Full sleep: The main power supply is shut down. A trickle supply provides auxiliary power to the PCI slots and keeps the DRAM state preserved for a quick recovery. All processors are powered off with their state preserved in DRAM. All clocks in the system are suspended except for the 32.768 KHz timebase crystal on the PMU99 IC. This mode allows the computer to meet the 5 W sleep requirement while providing the ability to start up without rebooting. This system may be awakened by administrative network packets, keyboard or mouse activity, USB device removal, or PMU scheduled wakeup.
Velocity Engine Acceleration
The Velocity Engine (an implementation of AltiVec) is the vector processing unit in the PowerPC G4 microprocessor. Some system software has been modified to take advantage of the accelerated processing that the Velocity Engine makes possible. System software has also been modified to support low-level operations using the Velocity Engine.
For complete information on the Velocity Engine, refer to the following Apple website:
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