Information Technology Reference
In-Depth Information
H
Microsoft Windows
H.1 Introduction
DOS has long been the Achilles heel of the PC and has limited its development. It has also
been its strength in that it provides a common platform for all packages. DOS and Windows
3.
x
operated in a 16-bit mode and had limited memory accessing. Windows 3.0 provided a
great leap in PC systems as it provided an excellent graphical user interface to DOS. It suf-
fered from the fact that it still used DOS as the core operating system. Windows 95/98 and
Windows NT have finally moved away from DOS and operate as full 32-bit protected-mode
operating systems. Their main features are:
•
Run both 16-bit and 32-bit application programs.
•
Allow access to a large virtual memory (up to 4 GB).
•
Support for pre-emptive multitasking and multithreading of Windows-based and MS-
DOS-based applications.
•
Support for multiple file systems, including 32-bit installable file systems such as VFAT,
CDFS (CD-ROM) and network redirectors. These allow better performance, use of long
file names, and are an open architecture to support future growth.
•
Support for 32-bit device drivers which give improved performance and intelligent mem-
ory usage.
•
A 32-bit kernel which includes memory management, process scheduling and process
management.
•
Enhanced robustness and clean-up when an application ends or crashes.
•
Enhanced dynamic environment configuration.
The three most widely used operating systems are MS-DOS, Microsoft Windows and UNIX.
Microsoft Windows comes in many flavours; the main versions are outlined below and Table
H.1 lists some of their attributes.
•
Microsoft Windows 3.
x
- 16-bit PC-based operating system with limited multitasking. It
runs from MS-DOS and thus still uses MS-DOS functionality and file system structure.
•
Microsoft Windows 95/98 - robust 32-bit multitasking operating system (although there
are some 16-bit parts in it) which can run MS-DOS applications, Microsoft Windows 3.
x
applications and 32-bit applications.
•
Microsoft Windows NT Version 4 - robust 32-bit multitasking operating system with in-
tegrated networking. Networks are around NT servers and clients. As with Microsoft
Windows 95/98 it can run MS-DOS, Microsoft Windows 3.
x
applications and 32-bit ap-
plications.
•
Windows NT Version 5/2000 - available as Workstation, Server and SMP Server (multi-
processor). It runs on Alphas, Intel
x
86, Intel IA32, Intel IA64 and AMD K7 (which is
similar to an Alpha).
