AMD's 64-Bit Chip

EyesWideOpen writes "AMD is set to release a 64-bit chip early next year which will be completely backwards compatible with the Athlon line. The current 64-bit offering from Intel, Itanium, is an entirely new chip that has no backwards compatibility with its x86 line of chips (from the 8080 chip to the Pentium IV) and is designed only for high end servers. AMD's solution to this problem is the Opteron chip (product info) which will be in servers, desktops and laptops. Here is a wired article."

Comments

Re:Of course backwards-compatible

[Gumber]

Of course, Itanium is backwords compatible with x86 code. It just isn't particularly fast when doing so.

ARM and Thumb instruction encodings

[yerricde]

"64-bit code is twice as big as 32-bit code" bloatware excuse

Unfounded. Though I find Itanium's instruction coding (16 bytes per 3 instructions) bloated, not all high-"bit" machines have to have bloated bytecodes. The ARMv4 architecture, used in processors such as the ARM7TDMI in the Game Boy Advance, has a standard 4-byte-per-instruction encoding, and an optional 2-byte-per-instruction encoding called "Thumb". Thumb code runs at about two-thirds of the speed of ARM code on machines with fast memory because some operations take more instructions on ARM than on Thumb, but Thumb code really shines when running on small or slow memory and can help drain less battery power on mobile machines. Apps will often have most of the app in Thumb but some of the time-critical inner loops in ARM.

Other Wired article errors

[clem.dickey]

The Wired article has other errors as well. A 32-bit CPU isn't limited to 4GB; that confuses address space with physical memory. The definition of exabyte is wrong (1000 petabytes, not 1000 terabytes). The 8080 in 1981? Closer to 1975. And many have mentioned the bogus "no compatibility" claim.

One wonders if the whole thing wasn't a troll.

Re:AMD FUD

[Perdo]

A dual 1Ghz Mac can emulate x86 and performs as well as a 266Mhz PII

A 667 mhz 64 bit Alpha can emulate x86 but is only as fast as a 200mhz Pentium Pro

An 800 Mhz Itanic emulates x86 as fast as a 166Mhz Pentium.

Linux can emulate a cluster on a single machine.

Any PC with two network cards can emulate a Cisco router.

Intel stopped marketing Itanium's x86 emulation mode because it is abysmally slow. The emulator is of course compiled on Itanium's still very immature compilers so it will improve in the future.

The Sledgehammer contains a complete x86 core and a complete 64 bit risc core. At 800mhz it outperforms a 1.6Ghz Pentium 4 running stock Windows XP and stock applications.

Running 64 bit SUSE, the Sledghammer performs as well as an Itanium at the same clock speed.

Sledgehammer is expected to ship at 2.0 Ghz. It's should perform as fast as a pentium 4 at 3.4 Ghz. Each processor has it's own memory controller so there is no shared memory bottleneck for multiprocessing. 2 processors should be exactly twice as fast using multithreaded applications. Sledghammer scales to 8 processors.