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Power Macintosh G3 (Blue

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The Power Macintosh G3 series (commonly known as the "Blue and White G3", or sometimes just the "B&W G3" to distingush it from the original "beige" G3 Power Macintoshes) was a series of personal computers designed, manufactured and sold by Apple Computer, Inc. as part of their Power Macintosh line. It was introduced in January 1999, succeeding the original "beige" Power Macintosh G3, with which it shared the name and processor architecture but little else; it was discontinued in favor of the Power Mac G4 line in August 1999.

The Blue & White G3 used a modified version of the memory/PCI controller, the Motorola MPC106 (codenamed "Grackle"); it used the MPC106 v4. The I/O "Heathrow" had been replaced by "Paddington" (adding 100 Mbit Ethernet and power save features), the audio chip "Screamer" (on the beige G3's "Personality Card") had been replaced by "Burgundy", and other controllers for Firewire (Texas Instruments PCI-Lynx), for USB etc. were added.

Note that "Paddington" only handles the slow IDE bus for CD/DVD and ZIP, in fact it provides up to 16.6 MB/s like its predecessor "Heathrow". The fast IDE bus for the hard disks is an extra chip and provides up to 33 MB/s; this one is the problem in the Rev 1 blue/white G3s.

Though still based on the PowerPC G3 architecture, the G3 B&W was a totally new design. The first new Power Mac model after the release of the iMac, it used a novel enclosure with the logic board on the "door", which swung down onto the desk for easy access (a design that was also used on all Power Mac G4 models except for the Cube). It also introduced the New World ROM to the Power Macintosh line.

[edit] Hardware

The faster models (not the 300 MHz model) used the new copper-based PowerPC G3 CPUs made by IBM, which used about 25% of the power of the Motorola versions clock for clock. The B&W line ranged from 300 to 450 MHz. Despite its 100 MHz system bus and PC100 SDRAM, the 300 MHz B&W G3 performed worse than its 300 MHz Beige predecessor, because it had only 512 KiB L2 cache, half of what the 300 MHz Beige had. The logic board had four PCI slots: three 64-bit 33 MHz slots, and one 32-bit 66 MHz slot dedicated for the graphics card, an ATI Rage 128 with 16 MiB SGRAM. Four 100 MHz RAM slots accepted PC100 SDRAM modules, allowing the installation of up to 1 GiB of RAM with the use of 256 MiB DIMMs. The onboard ATA was upgraded to Ultra ATA/33 (in fact an extra UDMA-33 controller was added, see above), but SCSI was no longer present, having been replaced by two FireWire ports, a new standard (IEEE1394) running at 400 Mbit/s (50 MB/s faster in theory than even the ATA/33 (33 MB/s) hard drive controller. The serial ports were gone, too, having given way to two USB 1.1 ports (12 Mbit/s), as implemented already in the iMac. The ADB port remained, as did the option for an internal modem. Also gone was the internal floppy disk drive. 100BASE-TX Ethernet was now standard, and audio was moved back to the logic board. A Zip Drive remained an option, and some configurations included a DVD-ROM drive and a DVD-Video decoder daughtercard for the graphics card, allowing hardware-assisted DVD video playback. The blue-and-white Power Macintosh G3 was the first Power Mac with the "New World" architecture based on Open Firmware. Initially, many buyers chose to buy the older "Platinum" G3s instead, in order to maintain compatibility with existing peripherals.

Early blue and white G3s ("Revision 1" units) had IDE controller problems related to the ATA/33 hard drive controller that made it impossible to connect two hard drives and prevented the use of newer drives. Using newer ATA drives in those units resulted in overwhelming data transmission errors, if the drives were connected to the on-board ATA/33 controller. This resulted in many users seeking remedies to solve this issue, including replacing their motherboards and employing the use of SCSI, Ultra ATA or SATA PCI controller cards as a workaround. Hard disk use on the secondary ATA channel was found to be impractical as the computer did not provide for hard disk booting via that channel and there was only a constrained unventilated space available for a hard disk connected to that channel which is unsuitable to many newer hard disks due to heat issues.

The secondary ATA channel has also been reported to have issues with respect to flash upgrading certain DVD burners, however otherwise it is generally held to be relatively stable.

The "Revision 2" units fixed the hard driver controller problem with an improved (UDMA-33) IDE controller that supported the standard IDE master/slave two-drive arrangement. This controller worked flawlessly with any drive within the 28-bit LBA constraint. Most Rev. 2 units shipped with a hard disk bracket designed for two drives (in fact Rev. 1 can hold up to three drives side-by-side, while Rev. 2 can hold up to four drives in two stacks, each with two drives) and also included a slightly updated version of the Rage 128 graphics card.


Revision B 350, 400 and 450 MHz units use the same motherboard as the first "Yikes" version of Power Mac G4 systems at 350 and 400 MHz ("Sawtooth" AGP-based G4s used a different board) and processor cards for these models are interchangeable. Note that if a G3's firmware has been upgraded (a required update for installing Mac OS 9), it won't accept G4 CPUs until patched with a third-party replacement firmware.

[edit] Sources

This article was started using a Wikipedia Macintosh G3 (Blue article
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