Motorola has introduced the MPC7450 PowerPC microprocessor.

The company says this is the highest performing microprocessor available today. The processor integrates AltiVec, called Velocity Engine by Apple. This is the third of four G4 PowerPC chips, and ships at speeds of 533, 667 and 733MHz.

The new chip has been installed in the two top-of-the-line Power Macs, introduced Tuesday. The two lower-spec Power Macs use the older 7410 chip, which has also been given a speed bump. Industry insiders claim Motorola delayed the availability announcement until after Steve Jobs' Macworld keynote speech on Apple's request. Motorola sources hinted at the imminent availability of the third-generation G4 chip in an interview with Macworld last autumn. Company sources predicted good news for Mac users in the first part of 2001. At the time, these sources would not confirm whether Apple was to install the new breed microprocessor in its machines.

Fast Jon Rubinstein, Apple's senior vice president of hardware engineering, said: "Apple's new Power Mac G4 line features a new high-performance architecture coupled with incredibly fast microprocessors running at up to 733MHz."

The new breed of microprocessors offer a seven-stage pipeline, with two additional execution units - this means instructions and data are processed significantly faster. The L2 cache has been integrated "onto the die", and this provides another speed bump. The processor also supports a large backside L3 cache with a fast datapath.

System bus The MPC7450 uses a high-performance system bus (MPX). It can reach sustained bandwidth performance of 1064MB per second - five times the bus performance of Motorola's G3 chips.

The AltiVec/Velocity Engine has also been improved. It can now despatch two instructions to any of the four AltiVec execution units per clock cycle. This means software instructions and data-crunching speeds get a much faster theoretical performance speed - if an application has been built with Velocity Engine support.

The microprocessors are manufactured using Motorola's proprietary HiPerMOS 6 0.18 copper fabrication process. This delivers chips with low-power requirements, something that enables Apple to offer low-noise fanless computers. Apple now offers these all across its reinvigorated product range.