Slashdot Mirror

Having the ability to process 32bit code on a 64bit chip if anything increases the speed because you can have two 32bit instructions run every cycle rather than a single 64bit instruction.

Not if, say, a 32-bit arithmetic instruction uses an entire ALU, as I think is the case on most 64-bit machines; I don't know if there are any that'd split a 64-bit ALU up into two 32-bit ALUs and run two 32-bit instructions through them (especially given that registers generally aren't split that way, either).

The SIMD "multimedia" instructions that most general-purpose instruction set architectures have picked up may process multiple less-than-full-word-size units in one ALU and in one instruction, but that's one instruction, not two.

Second of all Motorola already makes 64bit chips, these funny things called PowerPC chips. IBM and Apple use them, Apple runs 32bit code on the 64bit chip

What chips that implement the 64-bit version of the PowerPC instruction set does Apple use? (Chips that implement the 32-bit version of the instruction set, but that have a 64-bit bus interface, don't count as "64-bit chips" here.)

and now the 750 which is 128bit

No, it's 32-bit - it implements the 32-bit version of the PowerPC, without the AltiVec instructions, and according to this page at Motorola's Web site it has only a 64-bit bus interface for data.

Perhaps you're thinking of the 7400, which has the AltiVec instructions, but it also has only a 64-bit data bus, and only implements the 32-bit version of the core PowerPC architecture (note that the page for the 7400 links to the 32-bit version of the "Programming Environments Manual"), even if it also implements the AltiVec instructions that work on 128-bit registers.

Having the ability to process 32bit code on a 64bit chip if anything increases the speed because you can have two 32bit instructions run every cycle rather than a single 64bit instruction.

Not if, say, a 32-bit arithmetic instruction uses an entire ALU, as I think is the case on most 64-bit machines; I don't know if there are any that'd split a 64-bit ALU up into two 32-bit ALUs and run two 32-bit instructions through them (especially given that registers generally aren't split that way, either).

The SIMD "multimedia" instructions that most general-purpose instruction set architectures have picked up may process multiple less-than-full-word-size units in one ALU and in one instruction, but that's one instruction, not two.

Second of all Motorola already makes 64bit chips, these funny things called PowerPC chips. IBM and Apple use them, Apple runs 32bit code on the 64bit chip

What chips that implement the 64-bit version of the PowerPC instruction set does Apple use? (Chips that implement the 32-bit version of the instruction set, but that have a 64-bit bus interface, don't count as "64-bit chips" here.)

and now the 750 which is 128bit

No, it's 32-bit - it implements the 32-bit version of the PowerPC, without the AltiVec instructions, and according to this page at Motorola's Web site it has only a 64-bit bus interface for data.

Perhaps you're thinking of the 7400, which has the AltiVec instructions, but it also has only a 64-bit data bus, and only implements the 32-bit version of the core PowerPC architecture (note that the page for the 7400 links to the 32-bit version of the "Programming Environments Manual"), even if it also implements the AltiVec instructions that work on 128-bit registers.

the 32- versus 64-bit refers to the size of the instructions on the chip

No. Check out the PowerPC Programming Environments Manuals section of this page, and the (PDF) documents it links to. The instructions are 32 bits; the addresses and data they manipulate can be 64-bit in 64-bit PowerPC processors.

To me its not the end - its just another bringe on the same road because the athlon is still tied up to the original 80386 design wich was tied up to the 80086 design which was derived from the 4004 (Intels firts production processor).
I think the x86 line will be dead and the wintel marriage too when another architecture like the ARM or the PowerPC will make standard machines bought by normal end users .....

IPIX North American Sales
1-800-336-7113
sales@ipix.com

IPIX Stockhouse Manager, Jeff Puckett
1-888-909-IPIX
stock@ipix.com

IPIX CLIENTS
Suprisingly.. blank

Maybe you'd like to talk to their investors?

Motorola
Mediaone
Advance Internet
American Express
Financial Advisors
Cendant
General Electric
Invision
JP Morgan

--