Make your own free website on


December 29, 2002














(歷史: 以往CPU由16 bits 變成32bits時, 那時大機是用32bits的;

但現在64bits是用於大機; 但家用電腦的CPU又將進入64bits了)

那時大家到說沒有必要用32bits於家用電腦的, 現在又如何呢?....

這次改變與上次的改變, 又有何異同呢 ?!

(here is a brief history of x86 processors)



Fastest Computer New

20位科技菁英: 談科技大未來




Who needs 64 bits?
A surprising number of applications could benefit from 64 bit computing. AMD provided a number of examples:

  1. Databases
  2. Digital Content Creation
  3. CAD
  4. Electronic Design Automation
  5. Encryption
  6. Simulations

Databases can be accessed much more efficiently if 64 bit addressing is available. There are *many* databases with more than 4Gb of records; and even more databases that contain over 4Gb of information.

Don't misunderstand; it is quite possible to address very large database tables with 32 bit processors; it is just easier and more efficient if the processor supports 64 bit operations.

DVD drives are becoming common; and HDTV content is a prime candidate for editing on advanced PC's. TIVO and other similar devices may eventually obsolete VCRs. Digital content creation would also benefit from 64 bit addressing and processing.

CAD, EDA and simulations often deal with enormous models (of buildings, planes, bridges, weather, nuclear explosions, etc.); and you can imagine how such a model might well exceed 4Gb in size. As soon as you exceed the natural addressable range of a processor you have to resort to various "tricks" to address more data; a process that usually exacts a significant performance penalty.

Encryption/Decryption involves vast amounts of computation with large integers; and would benefit immensely from the availability of 64 bit registers and instructions. Just think of the boost to your RC5 standing!

Heck, even hard drives for PC's now store far more than 4Gb! Quite a few of you will have experienced difficulties with installing and using hard drives larger than your BIOS supported.

How to do 64 bits
Intel and AMD chose separate strategies for producing 64 bit processors. Both approaches have their strengths and weaknesses. Even though this article is about the 64 bit AMD x86 architecture I thought it would be useful to briefly discuss Intel's approach. But before that, here is a brief history of x86 processors...



For applications that use a lot of user% CPU, are there benefits to moving to 64-bit?


For applications doing 32-bit arithmetic with no need for large memory beyond 4GB, there is no clear benefit in moving to 64-bit.


Reference: 15465 / 17380

Date: 09 Sep 2002

Keyword: Base operating system, internals,,2:14631,00.html

How can I easily tell if a system is 64-bit enabled?

Answer: There are three requirements to having your RS/6000 run in 64-bit mode.

  1. The first is that the hardware must support it. The CPUs that support this are the Power3 (43P model 260) and the PowerPC RS64 4-way processor card (enterprise server model S70).
  2. AIX 4.3 is the first version of the operating system to support 64-bit.
  3. Finally, 64-bit must be enabled in the /etc/inittab. This is configured automatically during installation of AIX 4.3 for systems that support it.

So the simplest method to tell if your system can run 64-bit applications is to check the /etc/inittab:
# grep load64bit /etc/inittab
load64bit:2:once:/etc/methods/cfg64 >/dev/console 2>&1
# Enable 64-bit execs

Reference: 14631 / 16546 Date: 09 Sep 2002 Keyword: Base operating system, internals