PowerPC G3 is a designation used by Apple Computer to a third generation of PowerPC microprocessors from the PowerPC 750 family designed and manufactured by IBM and Motorola. The term is often, incorrectly, imagined to be a physical model of processor when in fact a number of processors from different vendors have been used.

The G3 is a RISC-based microprocessor, belonging to the PowerPC family of processors. Such designations were applied to Apple Macintosh computers such as the PowerBook G3, the multicolored iMacs, iBooks and several desktops, including both the Beige and Blue and White Power Macintosh G3s. The low power requirements and small size made the processors ideal for laptops and the name lived out its last days at Apple in the iBook. The 750 family processors is widely used in embedded devices like printers and storage devices, and is also used in other PowerPC based computers, like newer Amigas and Pegasos,

The 750 family had its shortcomings, namely lack of SMP support and SIMD capabilities and a relatively weak FPU. Motorola's 74xx range of processors picked up where the G3 left off.

PowerPC 740/750

The PowerPC 740/750 design (codename Arthur) was introduced in late 1997 as a evolutionary replacement for the PowerPC 603e. Enhancements included faster memory bus (66 MHz), larger L1 caches (32 kB instruction and 32 kB data), enhanced integer and floating point units and higher core frequency. The 750 model also included an option of 256, 512 or 1024 kB external L2 cache.

740/750 had 6.35 million transistors and was initially manufactured by IBM and Motorola in an aluminium based fabrication process. The die measured 67 mm² at 0.26 μm and it reached speeds of up to 366 MHz while consuming 7.3 W. In 1999, IBM used a copper based process at .20 μm which increased the frequency up to 500 MHz and decreased power consumption to 6 W and the die size to 40 mm².

The PPC 740 slightly outperformed Pentium IIs while consuming far less power, and being smaller in size. The off-die L2 cache of the 750 increased performance by approximately 30% in most situations. The design was so successful that it quickly beat 604e in performance and a planned successor to 604 was scrapped.

PowerPC 750 was used in many computers from Apple, including the original iMac.

BAE Systems manufactures a radiation hardened version of PowerPC 750, for use in space, called RAD750.

PowerPC 745/755

Motorola revised the 740/750 design in 1998 and shrunk die size to 51 mm² thanks to a newer aluminium based facrication at .22 μm. The speeds increased to up to 600 MHz. The 755 were used in some iBook models. After this model, Motorola chose not to keep developing the 750 processors in favour of their PowerPC 7400 processor and other cores.

PowerPC 750CX

IBM continued developing the 750 line and introduced 750CX (codename Sidewinder) in 2000 with 256 kB on-die L2 cache increasing performance, while reducing power consuption and complexity. At 400 MHz drawing under 4 W. 750CX had 20 million transistors including 256 kB L2 cache. Manufactured at a 0.18 μm copper process it hade a die size of 43 mm². 750CX was only used in one iMac revision.

PowerPC 750CXe

750CXe (codename Anaconda), introduced in 2001, was a minor revision of 750CX which increased it frequency up to 700 and memory bus to 133 MHz, from 100 MHz. Several models of iBook and the last G3 based iMac used this processor. The core of this processor is also the base of Gekko, the custom processor of Nintendo GameCube.

A cost reduced version of 750CXe, called 750CXr, is available at lower frequencies.

PowerPC 750FX

The 750FX (codenamed Sahara) came in 2002 and increased frequency up to 900 MHz, the bus speed to 166 MHz and the on-die L2 cache to 512 kB. It is manufactured using a 0.13 μm copper based fabrication with Low-K dielectric and Silicon on insulator technology. 750FX has 39 million transistors, a die size of 35 mm² and consums less than 4 W at 800 MHz at typical loads. It was the last G3 type processor used by Apple.

A low powered version of 750FX is available called 750FL.

PowerPC 750GX

750GX (codenamed Gobi), revealed in 2004 is the latest and most powerful G3 processor from IBM. It has a on-die L2 cache of 1 MB, top frequency of 1 GHz, support bus speeds up to 200 MHz among other enhancements compared to 970FX. It is manufactured using a 0.13 μm copper based fabrication with Low-K dielectric and Silicon on insulator technology. 750GX has 44 million transistors, a die size of 52 mm² and consums less than 9 W at 1 GHz at typical loads.

A low powered version of 750GX is available called 750GL.

Future

IBM have yet to officially announce any successor to 750GX or the future of the 750 family. Rumors has it that IBM once had a 750 type processor codenamed Mojave or 750VX under development with SMP and VMX support but this design have never been officially recognized and is assumed to be scrapped.

Freescale have all but abandoned all 750 designs in favour of e500 core based designs (PowerQUICC III).

PowerPC microprocessors

G3 (Prozessor) | PowerPC G3 | PowerPC G3 | PowerPC G3