Page 323 - DCAP103_Principle of operating system

Principles of Operating Systems

Notes Microsoft announced Multi-Tool Word for Xenix and MS-DOS in 1983. Its
name was soon simplified to Microsoft Word. Free demonstration copies of
the application were bundled with the November 1983 issue of PC World,
making it the first program to be distributed on-disk with a magazine.
10.1.4 Windows 2000

The release of NT following NT 4.0 was originally going to be called NT 5.0. However, in 1999,
Microsoft changed the name to Windows 2000, mostly in an attempt to have a neutral name that
both Windows 98 users and NT users could see as a logical next step for them. To the extent
that this approach succeeds, Microsoft will have a single main operating system built on reliable
32-bit technology but using the popular Windows 98 user interface.
Since Windows 2000 really is NT 5.0, it inherits many properties from NT 4.0. It is a true 32-bit
(soon to be 64-bit) multiprogramming system with individually protected processes. Each process
has a private 32-bit (soon 64-bit) demand-paged virtual address space. The operating system
runs in kernel mode, whereas user processes run in user mode, providing complete protection
(with none of the protection flaws of Windows 98). Processes can have one or more threads,
which are visible to, and scheduled by, the operating system. It has Department of Defense C2
security for all files, directories, processes, and other shareable objects (at least, if the floppy
disk is removed and the network is unplugged). Finally, it also has full support for running on
symmetric multiprocessors with up to 32 CPUs.
The fact that Windows 2000 really is NT 5.0 is visible in many places. For example, the system
directory is called \winNT and the operating system binary (in \winNT\system32) is called
ntoskrnl.exe. Right clicking on this file to examine its properties shows that its version number
is 5.xxx.yyy.zzz, where the 5 stands for NT 5, xxx is the release number, yyy is the build
(compilation) number, and zzz is the minor variant. Also, many of the files in \winNT and its
subdirectories have NT in their names, such as ntvdm, NT’s virtual MS-DOS emulator.
Windows 2000 is more than just a better NT 4.0 with the Windows 98 user interface. To start
with, it contains a number of other features previously found only in Windows 98. These
include complete support for plug-and-play devices, the USB bus, IEEE 1394 (FireWire), IrDA
(the infrared link between portable computers and printers), and power management, among
others. In addition, a number of new features not present in any other Microsoft operating
system have been added, including active directory service, security using Kerberos, support
for smart cards, system monitoring tools, better integration of laptop computers with desktop
computers, a system management infrastructure, and job objects. Also, the main file system,
NTFS, has been extended to support encrypted files, quotas, linked files, mounted volumes, and
content indexing, for example. Another novel NTFS feature is the single instance store, which is
a kind of copy-on-write link in which two users can share a linked file until one of them writes
on it, at which time a copy is made automatically.
One of the other major improvement is internationalization. NT 4.0 came in separate versions for
different languages with the text strings embedded in the code. Installing an English software
package on a Dutch computer often caused parts of the operating system to stop using Dutch
and start using English because certain files containing code and text strings were overwritten.
This problem has been eliminated. Windows 2000 has a single binary that runs everywhere in
the world. An installation, or even an individual user, can choose the language to use at run
time because all the menu items, dialog strings, error reports, and other text strings have been
removed from the operating system and put in separate directories, as per installed language.
Like all previous versions of NT, Windows 2000 uses Unicode throughout the system to support
languages not using the Latin alphabet, such as Russian, Greek, Hebrew, and Japanese.
One thing that Windows 2000 does not have is MS-DOS. It is simply not there in any form (nor
was it there in NT). There is a command line interface, but this is a new 32-bit program that
includes the old MS-DOS functionality and considerably new functionality as well.

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