A major leap forward was made in this model through the introduction of a large level 2 backside cache which reduced data bottlenecks and allowed very efficient use by the computer of its bus speed. Because of this, at the time Power Mac G3 machines were widely considered to be faster than Intel PCs of similar CPU speed. The Power Mac G3 was originally intended to be a midrange series, between the low-end Performa/LC models and the high-end Power Mac 8600 and 9600. During development, it quickly became evident that the G3 was a much faster machine than the 604-based Macs, so the Power Mac G3 became the flagship instead.
The original "platinum" Power Mac G3 series (commonly called "beige G3s") came in two versions: a desktop enclosure inherited directly from the Power Mac 7300, and a minitower similar to (but shorter than) the Power Mac 8600 enclosure. Equipped with a 233, 266, 300, or 333 MHz PowerPC G3 CPU from Motorola, these machines used a 66MHz bus and industry-standard PC66 SDRAM, and were one of the first Power Macs to use IDE hard disk drives. These machines had no audio circuitry on the logic board. Instead, a slot for a "personality card" was populated with an audio card on regular versions, while AV versions included a card that added S-Video capture and output. DVD-ROM drives were now an available option, and Zip drives continued to be available as well. These machines had onboard SCSI, ADB, 10Base-T Ethernet, two serial ports, and onboard ATI graphics (originally Rage II, later updated to Rage Pro) with slots for VRAM upgrade. 3 PCI slots and one internal modem slot rounded out the features.
Some early platinum G3s do not support slave devices on their IDE controllers, limiting them to one device per bus (normally one optical drive and one hard disk). This problem was tracked to Revision A logic boards and does not happen in Mac OS X.
Blue and White G3
The Power Mac G3 (Blue and White) series, introduced in early 1999, was a totally new design. The first new Power Mac model after the release of the iMac, it used a novel new enclosure with the logic board on the "door", which swung down onto the desk for easy access. (This case style was also used on all Power Macintosh G4 models except for the Cube.) These models used the new copper-based PowerPC G3 CPUs made by IBM, which used about 1/4 the power of the Motorola versions. 300, 350, 400, and 450MHz versions were made. The logic board had four PCI slots: three 64-bit 33MHz slots, and one 32-bit 66MHz slot dedicated for the graphics card, an ATI Rage 128. Four RAM slots accepted PC100 SDRAM modules, allowing for a maximum of 1GB of RAM, running on a 100MHz bus. The onboard IDE was upgraded to Ultra ATA/33, but SCSI was no longer present, having been replaced by two FireWire ports. The serial ports were gone, too, having given way to two USB 1.1 ports. The ADB port remained, as did the option for an internal modem. 100Base-TX Ethernet was now standard, and audio was moved back to the logic board. Zip remained as 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 Mac G3 was the first Power Mac with the "New World" architecture based on Open Firmware, as well as the first Power Mac without onboard SCSI. Initially, many buyers chose to buy the older platinum G3s instead, in order to maintain compatibility with existing peripherals.
Early blue and white G3s had IDE controller problems, which make it impossible to connect two hard drives and prevent the use of most hard disk drives produced after them. (Using newer drives in those units results in massive data transmission errors.) The "Rev B" units have a corrected IDE controller which allows two hard disks, and works flawlessly with any drive, within the 28-bit LBA constraint. The Rev B units ship with a hard disk bracket designed for two drives and also have an updated graphics card.
Sources and References
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