Power Macintosh G3

From Academic Kids

The Power Macintosh G3 was a series of personal computers made by Apple from November 1997 to August 1999. It used the PowerPC G3 (PPC750) microprocessor.

A major leap forward was made in this model through the introduction of a fast, large Level 2 backside cache, running at half processor speed, which reduced data bottlenecks and allowed very efficient use by the computer of its bus speed; 512KB on the 233 MHz and 266 MHz models, 1 MB on the 300 MHz, 333 MHz and later models. Because of this, at the time Power Mac G3 machines were widely considered to be faster than Intel PCs of similar CPU clock 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 faster machine than the PPC604-based Macs, so the Power Mac G3 became the flagship instead, and the PPC60x architecture was dropped altogether from the desktop line.

Beige G3s

The original "platinum" Power Macintosh G3 series (commonly called "beige G3s") came in three versions: a desktop enclosure inherited directly from the Power Mac 7300; a minitower similar to (but shorter than) the Power Mac 8600 enclosure; and a version with a built in screen, the G3 All-In-One, available only to the educational markets. Equipped with a 233, 266, 300, or 333 MHz PowerPC G3 CPU from Motorola, these machines used a 66.83 MHz bus and industry-standard PC66 SDRAM, and used IDE hard disk drives.

There were 233, 266 and 300 MHz desktop models, and 233, 266, 300, and 333 MHz minitower models. The 233 and 266 MHz DT models shipped with 4 GB HDDs, and the 300 MHz with a 6 GB drive, all at 5400 rpm. The 233 MHz minitower shipped with a 4 GB drive, the 266 MHz with a 6 GB drive, and the 300 MHz minitower shipped with two 4 GB drives; all models were 5400 rpm. The 300 MHz minitower was replaced by the 333 MHz tower, which shipped with a 9 GB 7200 rpm SCSI drive, attached to a SCSI/PCI card– also, it had a 100BT ethernet PCI card. Unlike its predecessor, the 300 MHz MT, it had only 6 MB VRAM, because the 300 MHz model shipped with a 128-bit iXMicro PCI video card with 8 MB VRAM. Half of the AIO's case was translucent, suggesting what might come with the iMac. The AIO shipped in two basic configurations, a 233 MHz version with a floppy drive and a 4 GB hard drive, and a 266 MHz version with a built in Zip drive, floppy drive, and the "Wings" personality card.

These machines had no audio circuitry on the logic board. Instead, a PERCH slot (a dedicated 182–pin microchannel connector, which is a superset of the PCI spec, but doesn’t accept PCI cards) for a "personality card" was populated with a "Whisper" personality card on regular versions, offering 16-bit, 44 kHz audio I/O, or a "Wings" personality card, an AV version which included S-Video capture and output, as well as composite I/Os. DVD-ROM drives were now an available option, and Zip drives continued to be available as well. These machines had onboard SCSI, from the 53C96 SCSI controller, ADB, 10Base-T Ethernet, two serial ports, and onboard ATI graphics (originally Rage IIc, later updated to Rage Pro and then Rage Pro Turbo) with slots for VRAM upgrade. 3 PCI slots and one internal modem slot, as well as 3 SDRAM slots (for up to 768 MB RAM) rounded out the features.

Early Platinum G3s with Revision A ROMs do not support slave devices on their IDE controllers, limiting them to one device per bus (normally one optical drive and one hard disk).

Blue and White G3s

The Power Macintosh G3 (Blue and White) series, introduced in January 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 450 MHz versions were made. 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 MB SGRAM. Four RAM slots accepted PC100 SDRAM modules, allowing for a maximum of 1 GB of SDRAM, running on a 100 MHz bus. The onboard IDE was upgraded to Ultra ATA/33, but SCSI was no longer present, having been replaced by two FireWire ports, a new standard (IEEE1394) running at 400 Mbit/s (50 Mbit/s). The serial ports were gone, too, having given way to two USB 1.1 ports, as implemented already in the iMac G3. 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 Mac without onboard SCSI since it was introduced on the Mac Plus. 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.

External links

fr:Power Macintosh G3 Desktop fr:Power Macintosh G3 Minitour fr:Power Macintosh G3 Tout-en-un fr:Power Macintosh G3 (Bleu et Blanc)


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