PC Hardware in a Nutshell, 3rd Edition [Electronic resources] نسخه متنی

1.1 PCs Defined

Who decides what is and what is not a PC?
That question is not as trivial as it sounds, because there has never
been (and probably will never be) an all-embracing

de
jure standard to define the PC. IBM created the

de facto PC standard (and trademarked the name)
when it shipped the first IBM Personal Computer in 1981. For more
than five years, until its introduction of the ill-fated proprietary
PS/2 line in 1987, IBM defined the PC standard. For a short timethereafter, some considered that Compaq defined the standard. But the
days when any PC maker defined the PC standard are far in the
past.

These days, Intel and Microsoft
jointly define the

de facto PC standard. In
fact, a good working definition of a PC is a computer that uses an
Intel or compatible processor

and can run a
Microsoft operating system. Any computer that meets both
requirementsa so-called Wintel
computeris a PC. A computer that does not is not. Computers
based on some Intel processors cannot run any Microsoft operating
system, and thus are not PCs. Conversely, some computers with
non-Intel processors can run Microsoft operating systems, but do not
qualify as PCs. For example, DEC Alpha minicomputers running Windows
NT 4 are not PCs.

Two formal documents, described in the following sections, define the
joint Intel/Microsoft standards for systems and components you are
likely to be working with. These standards are

de
facto in the sense that system and peripheral makers are
not required to comply with them to manufacture and sell their
products. They might as well be

de jure
standards, however, because compliance is required to achieve such
nearly mandatory certifications as inclusion on the Windows
NT/2000/XP Hardware Compatibility Lists.

1.1.1 PC 99 System Design Guide

PC 99 System Design Guide


(PC 99) is a
book-length document that defines required, recommended, and optional
(neither required nor recommended, but must meet the standard if
included) characteristics for several classes of PCs, including
Basic PC 99 (further subdivided into
Consumer PC 99 and Office PC
99), Workstation PC 99,
Entertainment PC 99, and Mobile PC
99.

PC 99 is the penultimate member of a series of
documents, which began in 1990 with the first MPC standard, and
continued with the

PC 95 ,

PC
97 , and

PC 98 revisions.

PC
99 was formalized in mid-1998, took partial effect in July
1999 for systems to be delivered in Q4 1999, came into full effect
January 1, 2000, and defined the standards for systems and components
delivered through late 2001. In some ways,

PC 99
was unrealistically far ahead of its timefor example, in
recommending Device Bay and 1394 as standard storage interfaces. In
other ways, it was far behindfor example, in requiring only a
300 MHz processor and 32 MB of RAM for some configurations. Some
portions are skewed to Intel CPUs (e.g., an L2 cache requirement was
cut from 512 KB to 256 KB when Intel shipped Coppermine Pentium III
CPUs with 256 KB L2 cacheprobably not a coincidence), while
many others are skewed toward Microsoft operating systems. Neither of
those is surprising in the document that defines the Wintel standard.
All of that said,

PC 99 was and remains an
important document because it defined the direction of PC development
as we entered the new millennium.

You can purchase

PC 99 in book form (Microsoft
Press, 1998, ISBN: 0-7356-0518-1). You can view or download

PC 99 1.0 in Acrobat format (http://www.pcdesguide.org/) or

PC
99a the final release of

PC 99 ,
with minor updates and correctionsin compiled HTML help format
(http://www.microsoft.com/hwdev/platform/pcdesign/desguide/default.asp).
The PC Design Guide home page (http://www.pcdesguide.org) also contains
links to these documents in various formats.

If you've ever crawled around under a desk trying to
read the tiny icons on port connectors, you'll
appreciate one very visible manifestation of PC 99
compliancestandard colors for port connectors, listed in Table 1-1. Nearly all PCs and peripherals shipped since
Q4 1999 use these colors.

1.1.2 PC 2001 System Design Guide

The

PC 2001
System Design Guide (PC 2001) is,
according to Intel and Microsoft, the final document in this series.
In many respects,

PC 2001 is more an addendum to

PC 99 than a self-supporting document. Many PC
2001 specifications direct the reader to PC 99 and state only that
the PC 2001 requirements are identical to those of PC 99, or are
similar to those of PC 99 but with minor changes specified. The major
differences between PC 99 and PC 2001 are:

PC 2001 eliminates the strong emphasis of PC 99 on market
classificationsBasic PC, Consumer PC, Entertainment PC, and so
onalthough it does specify different requirements for
workstations and Mobile PCs where appropriate.

PC 2001 no longer categorizes components and functionality as
"recommended," instead specifying
only those that are required. A component or function that is not
required is not mentioned. Some requirements, identified as
"if implemented," are conditional.
If a manufacturer provides that component or feature, it must comply
with the specified standard.

PC 2001 eliminates some former requirements because Microsoft and
Intel deem them no longer important to the industry or
"no longer relevant in defining the optimal user
experience with the Windows operating system,"
whatever that means.

PC 2001 defines requirements intended to support new and forthcoming
technologies implemented in recent Microsoft operating systems,
including Windows 2000, Windows Me, and Windows XP.

PC 2001 places a greatly increased emphasis on legacy-reduced and
legacy-free systems. Some "legacy"
items such as ISA expansion slots and device dependence on MS-DOS are
forbidden entirely, while others are merely strongly discouraged.

PC 2001 emphasizes (although it does not mandate) features that are
collectively called the Easy PC Initiative, which focuses on ease of
setup, use, expansion, and maintenance.

You can download a copy of

PC 2001 in Word, PDF,
or Microsoft Compiled Help format from http://www.pcdesguide.org.