Append B （附录 B ） The Alpha AXP Processor
Alpha AXP 体系结构是一个为了速度而设计的 64 位的加载 / （ load/store ） RISC 体系结构。所有的寄存器都是 64 位长的： 32 个整数寄存器和 32 个浮点寄存器。第 31 个整数寄存器和第 31 个浮点寄存器用于 null 操作：读取它们得到 0 ，写向它们没有任何结果。所有的指令和内存操作（不管是读或写）都是 32 位。只要具体的实现遵循这种体系结构，允许不同的实现方式。
没有直接在内存中操作数值的指令：所有的数据操作都是在寄存器之间进行。所以，如果你希望增加内存中一个计数器，你必须首先把它读到一个积存其中，修改之后再写回去。只有通过一个指令写向一个寄存器或内存位置，而另一个读取这个寄存器或内存位置，指令之间才能过相互作用。 Alpha AXP 的一个有趣的特点是它有可以产生标志位的指令，比如两个整数是否相等，这个结构不是存放到处理器的一个状态寄存器，而是存放到第三个寄存器。初看上去比较奇怪，但是不依赖于状态寄存器意味着可以更容易地让这个 CPU 每一个循环执行多个指令。执行过程中使用无关的寄存器的指令不需要互相等待，如果只有一个状态寄存器则必须等待。没有对于内存的直接操作以及数目众多的寄存器对于同时多条指令也有帮助。
Alpha AXP 体系结构使用一系列子例程，叫做体系结构的授权库代码（ privileged architecture library code PALcode ）。 PALcode 和操作系统、 Alpha AXP 体系的 CPU 具体实现和系统硬件相关。这些子例程向操作系统提供上下文切换、中断、异常和内存管理的基本支持。这些子例程可以被硬件调用或通过 CALL_PAL 指令调用。 PALcode 用标准的 Alpha AXP 汇编程序编写，带有一些特殊扩展的实现，用于提供直接访问低级硬件的功能，例如内部处理器的寄存器。 PALcode 在 PAL 模式运行，这是一个特权的模式，会停止一些系统事件的发上，并允许 PALcode 完全控制系统的物理硬件。
Appendix C （附录 C ）
Useful Web and FTP Sites （有用的 web 和 ftp 站点）
~axp This is David Mosberger-Tang's Alpha
AXP Linux web site and it is the place to go for all of the Alpha AXP HOW-
TOs. It also has a large number of pointers to Linux and Alpha AXP specific
information such as CPU data sheets.
Red Hat's web site. This has a lot of useful pointers.
ftp://sunsite.unc.edu This is the major site for a lot of free software. The Linux
specfic software is held in pub/Linux.
Intel's web site and a good place to look for Intel chip
information.
The Linux Journal is a very good Linux
magazine and well worth the yearly subscription for its excellent articles.
This is the primary site for infor-
mation on on Linux.
ftp://tsx-11.mit.edu/ ~ftp/pub/linux MIT's Linux ftp site.
ftp://ftp.cs.helsinki.fi/pub/Software/Linux/Kernel Linus's kernel sources.
The UK Linux User Group.
Home page for the Linux Documen-
tation Project,
Digital Equipment Corporation's main web page.
DIGITAL's Altavista search engine. A very good
place to search for information within the web and news groups.
The Linux HQ web site holds up to date offical and
unoffical patches as well as advice and web pointers that help you get the best
set of kernel sources possible for your system.
The AMD web site.
Cyrix's web site.
Appendix D( 附录 D)
The GNU General Public
License
Printed below is the GNU General Public License (the GPL or copyleft), under
which Linux is licensed. It is reproduced here to clear up some of the confusion
about Linux's copyright status|Linux is not shareware, and it is not in the public
domain. The bulk of the Linux kernel is copyright c 1993 by Linus Torvalds, and
other software and parts of the kernel are copyrighted by their authors. Thus, Linux
is copyrighted, however, you may redistribute it under the terms of the GPL printed
below.
GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc. 675 Mass Ave, Cambridge,
MA 02139, USA Everyone is permitted to copy and distribute verbatim copies of
this license document, but changing it is not allowed.
D.1 Preamble
The licenses for most software are designed to take away your freedom to share and
change it. By contrast, the GNU General Public License is intended to guarantee
your freedom to share and change free software{to make sure the software is free
for all its users. This General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to using
it. (Some other Free Software Foundation software is covered by the GNU Library
General Public License instead.) You can apply it to your programs, too.
When we speak of free software, we are referring to freedom, not price. Our General
Public Licenses are designed to make sure that you have the freedom to distribute
copies of free software (and charge for this service if you wish), that you receive
source code or can get it if you want it, that you can change the software or use
pieces of it in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid anyone to deny
you these rights or to ask you to surrender the rights. These restrictions translate
to certain responsibilities for you if you distribute copies of the software, or if you
modify it.
For example, if you distribute copies of such a program, whether gratis or for a fee,
you must give the recipients all the rights that you have. You must make sure that
they, too, receive or can get the source code. And you must show them these terms
so they know their rights.
We protect your rights with two steps: (1) copyright the software, and (2) offer you
this license which gives you legal permission to copy, distribute and/or modify the
software.
Also, for each author's protection and ours, we want to make certain that everyone
understands that there is no warranty for this free software. If the software is modified
by someone else and passed on, we want its recipients to know that what they have
is not the original, so that any problems introduced by others will not re ect on the
original authors' reputations.
Finally, any free program is threatened constantly by software patents. We wish to
avoid the danger that redistributors of a free program will individually obtain patent
licenses, in e
ect making the program proprietary. To prevent this, we have made it
clear that any patent must be licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and modification follow.
D.2 Terms and Conditions for Copying, Distribu-
tion, and Modification 0. This License applies to any program or other work which contains a notice
placed by the copyright holder saying it may be distributed
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