Basic knowledge about Operating Systems

2081 words - Last update: 2016-08-21 Page created: 2004-04-03 [SB]

Basic knowledge

How did the web sites of the companies look like earlier?
Which operating systems are there for the PDA?
Where can I find the glossary about operating systems?
What are file systems and how different are these?
What is the operating system core or so called kernel?
What is a RISC/CISC architecture or Platform?
Where can I find some references for information purposes?

Operating System

To understand better how an operating system linked between the hardware and the application programs the following layer model is helpful. Since the time-sharing era of the operating systems the process and the resource allocation become controlled themselves. The general structure of an operating system is appropriate described as follows: "The more software layers of the hardware surround, the better the application variety and interface can be optimized to the user. By these abstraction layers a computer gets only right useable for the user."

This model is built up purely schematically, for comparison purposes the following operating system models are compareable:

BeOS | JavaOS | Linux | OS/2 | Solaris
Windows 98 | Windows CE | Windows NT | Windows XP
Windows Server 2003

operating system model

Hardware Depending on design concept programs the hardware access is allowed directly or only over additional layers. Over additional layers the performance is reduced a little and in contrast in the context of direct access the performance arised.

Layer 1: HAL (Hardware Abstraction Layer) The Hal makes the use on a hardware platform possible for which the especially processor architecture is designed. Architectures are the x86, alpha, PowerPC or SPARC. If the porting of the operating system for other platforms is in the foreground, the Hal has a central role for the porting.

Layer 2: File system, drivers Important tasks of the operating system is the representation of several file systems which is practicable realized virtually over corresponding driver. Additional functions like encrypting or compression are also included. Driver software for standard components like keyboard, LPT or COM interfaces are supported directly by the operating system rudimentarily like in DOS for example. Modern operating systems have standard driver software included for most hardware components. The manufacturers provide driver software of their own for extended functions and optimal performance for her hardware.

Layer 3: Management The management layer provides the smooth process of system processes by cooperative, präemptives or real time multitasking. Depending on priority the operating system assigns CPU time, memory and I/O accesses to the process.

Layer 4: System interface (kernel) The system interface separates the operating system core of the API, frequently it serves also as separation mark of the CPU mode of the privileged ring 0 of the kernel.

Layer 5: API (Application Program Interface) With software interfaces like the Win32 API different programs use unlocked operating system functions like copy or open dialog for file transfers. These are provided to all programs uniformly with parameters about standard application instructions. Remote data transmission services for example.

Libraries Libraries provides the operating system and applications ready to use program parts for simplified access to different functions. By libraries (.dll, .OCX, ...) developers can use frequently required functions without having to invent these for the application newly.

Applications Application programs use the resources and device time allocated by the operating system for use. The user interacts with the computer over appropriate input and output devices.

Executable programs

Files that contain by operating systems executable program code can be recognized by the file ending (Windows) and under some operating systems directly by the file format (UNIX and derivatives). Files with the file extension *.com are obviously for DOS, *.exe applications can be 16-bit, 32-bit or also for 64-bit Windows operating systems be applicable. Before Windows 95 there are only 16-bit applications (with a Win32 extension also few 32-bit applications), since Windows 95 for booth 16-bit and and 32-bit programs. There then still is the newer *.msi file format of Microsoft which contains the program and the assisting installation script in especially packed text form. Parts of the program code are paged out also in *.dll files, the depending "part of the application" takes advance of it and execute in the context of the application the code from the DLL file. Under Windows the Visual BASIC files and the .NET framework are example of it.

Behind the file format *.rpm for Linux, an established standard by Red Hat for software with an integrated installation routine, can contain only the source code of an application or in compiled form especially for a distribution. This can be recognized on abbreviations like "src" for source code or "mdk" for a Mandrake Linux distribution. The applications are ELF-Binaries without file extension, about the file header and the file attribute "executably" a runable application for the user depending on assigned file rights.

The *.pkg format is used under BeOS for files with one own installation routine.

Market shares of the operating systems

To obtain a summary of the market shares in the server and desktop area of the operating systems different market research firms accomplished analyses. The results are presented in the public media and afterwards only to the client or the paying customer. From the following sources informations about the market shares of operating systems can be gathered. The market researchers based up her results on interviews and sales numbers by the manufacturer, the number of operating systems that are can freely copied are not ascertainable thereby. Only the sales figures of the commercial Linux distributors are taken into the reports. It has to be examined if multiple installations on a desktop PC and virtual operating system installations on servers were counted too. So the studies are based upon estimated values. Studys of IDC and Gartner which have the same topic often differs from each other depending on the used method at the elevation of the numbers.

The company IDC (International Data Corporation) with headquarter in the USA is a daughter enterprise of the IDG (International Data Group Inc.) and was founded in 1964 and has worldwide offices. IDC creates reports for current numbers of market shares by operating systems and about many other information fields. IDC creates forecasts about the future development and determines current market numbers from the sales figures of the manufacturer and interviews. Since 1979 exists the enterprise Gartner which has also his headquarter in the USA and is represented worldwide. Gartner creates market analyses especially for the IT area and supports his customers at the decision finding in special questions by the making of detailed reports. There still is the company Netcraft since 1995 next to the formerly named two enterprises with headquarters in England which is especially specialized in the Internet area. Netcraft provides publicly information about the used operating systems on servers besides to other information areas on the Internet. It has to considered that Netcraft taken into account only the first checked URL of a web site for the operating system determination. Entry pages can run in enterprises on another server like for load balancing as the interlinked enterprise web site and differs often in the operating system. Maybe one server is counted multiple times because it is hosting several web presences with that operating system. For security reasons maybe the operating system identification is different fro mthe real used operating system to cover the correct operating system up and provide false information to a possible attacker.

Netcraft has pointed out the portions of Linux distributions in a news of 12/05/2005 on web servers. Red Hat reached up to 34% followed by Debian with 25% and the greatest growth, Fedora 16%, SuSE 11%, cobalt 7%, gentoo 3%, Mandriva and Centos comes with 3 % each.

IDC published the proportionate sales of the servers operating systems for the 1st quarter 2005 in a press release on 26-5-2005. In the total turnover of 12.1 billion U.S. dollars 4.2 billion U.S. dollars are assigned to Windows and UNIX servers each, with Linux servers were had a turnover of 1.2 billion U.S. dollars. 2.5 billion U.S. dollars are assigned to other servers operating systems.

IDC has published a study (PDF for download) which was accomplished in the job of the OSDL. Examined was the development of the operating system Linux in the desktop and server market. As a result it came out that Linux has established itself and the sales volume related to Linux will increase to 2008 in the software market to about 35.7 billion U.S. dollars and obtain approximately a share of 28% in the server market. The sold number shall reach 17 million Linux installations at new and upgraded PCs in the desktop market in the year 2008. Altogether it shall reach in the desktop and server area 42.6 million Linux installations at all.

Netcraft had released a news on 12-7-2004 with the current numbers of the Linux distributions on web servers. The number of active web sites for Linux amounted to 2,944.979 in the sum, Linux Red Hat comes up to about 49.8%, Cobalt on 20.3%, Debian 15.9%, SuSE 11.8%, Mandrake 1.3% and gentoo on 1.0%.

heise online published the report on 8-10-2003 Microsoft-Betriebssysteme dominieren weiter (Microsoft operating systems are dominate further) with the following information. In the year 2002 121 million licences were sold in the desktop area. These divide Windows with estimated 93.8 %, Mac OS with 2,9 %, Linux with 2,8 % and other operating systems with 0,5 %. On the 5.7 million server operating systems sold 55.1 % been allotted to Windows operating systems, to Linux 23.1 %, Unix with 11 % and Novell Netware 9.9 %.

IDC published the figures of the market shares for the year 2001. The Microsoft Windows operating systems came os 2.2%, Linux on 2.1%, up to 93.2%, Mac in the sales figures in the desktop market. Microsoft obtained a quota of 49%, Linux 22.4%, NetWare 11.7%, UNIX 11.6%, in the server market.

IDC published the figures of the market shares in March 2001 for the year 2000. The Microsoft Windows operating systems (95/98/NT/2000/ME) came in the sales numbers in the desktop market up to 93,2%, Mac OS to 4%, Linux on about 2%. Microsoft obtained a share in the server market of 42%, Linux 27%.

With the determination of the operating systems on which a Website and not only the hostname is really hostet, Netcraft released in one news of June 2000 the following numbers. The number of active web sites amounted to 7,727.817, Linux 29.99%, Microsoft 28.32%, other operating systems 23.59%, Solaris 16.33%, 1.76% unknown.

IDC published the figures of the operating systems sold in the market for the current year in December 1998. In the server market Windows NT achieved 36%, Linux 17%, Novell Netware 24%, UNIX derivatives 23%.