G4

G4 is the name for a fourth-generation Motorola-developed processor part of the 74xx series. The RISC-based PowerPC processors were part of Apple computers Mac product line, despite being developed by Motorola. The chip in question featured a popular vector processing technology that Apple dubbed Velocity engine, and that uses an approach called SIMD  or Single Instruction, Multiple Data.

 

Technipages Explains G4

SIMD allowed the processor to perform the same action on up to 16 pieces of data at once, instead of having to repeat that operation 16 individual times. This effectively increased the processor’s speed, as it cut out repeat processes, but it could only help where the exact same action was required – even just slightly different ones still had to be executed in order rather than simultaneously. SIMD also required existing software to be rewritten in order to take advantage of the Velocity engine.

These processors were among the first in this category that were able to cross the 1GHz clock speed mark – a milestone, albeit even slow modern processors are several times faster than that now. The G4 series was 32bit-based and was quickly phased back out when Apple switched to the 64-bit based G5 models that followed the G4. The very first processor labelled as part of the G4 family came out in 1999, and was codenamed Max – the  PowerPC 7400. Other models followed suit, and half a dozen or so machines later, by the year 2005, the last model featuring the G4 processor was released – the PowerPC 7448 nicknamed Apollo 8.

Common Uses of G4

• G4 is a designation used by Apple to describe the generation of PowerPC CPUs used in its G4 generation of computers.
• The G4 CPUs were designed by Motorola in 1999, the first to carry the designation was the PowerPC 7400 CPU.
• The G4 class of CPUs was designed in close cooperation with Apple and IBM.

Common Misuses of G4

• The brand-name G4 refers to a specific CPU and not a range.