Knowledge, Glossary about Operating Systems

1613 words - Last update: 2013-10-14 Page created: 2004-04-03 [SB]


Here you find the term explanation supplementing to the most important terms related with operating systems.

ACPI Advanced Configuration Power Interface stands for energy functions to make it at example possible to connect or remove a laptop computer to the docking station without restart. The OnNow energy saving function can shift an ACPI compatible computer to sleep mode and back to normal mode. Suspend to disk is another mode which awakes the computer from the sleep mode in short time to recover the last running operating system state. Modern mainboards supports the power on of the computer about keyboard input and other interfaces in the BIOS.

The API, Application Program Interface serves as standardized programming interface between operating systems and programs. Example is the Win32c API in Windows 95 and Windows 98 SE which is partly also compatible with 32-bit Windows programs of Windows NT.

AppleTalk is the standard network protocol of Macintosh computers for the common access to files and printers.

BASIC The Beginner's All-purpose Symbolic Instruction Code is a simple programming language for realtime interpreted programs by the BASIC interpreter.

The Desktop is the essential component of a graphical user interface of a operating position for the function as work desk. The user has comparatively as well access to his documents and tools like on a real work desk.

GUI The Graphical User Interface was invented as method by research and publications of Dr. V. Bush in 1945 and described as simply access to informations with a graphical interface on computers. At that time, the design model Memex could not be built. With the development of the mouse in the sixties as a pointing equipment for computer it was for the first time possible to use graphical user interfaces efficiently. PARC (Palo Alto Research Centre) started with the first developments of this technique with personal computers at Xerox in the seventies. In the same time period Xerox published the first personal computer with graphical interface and overlaid windows, Xerox Alto was mainly used in education facilities. With the Xerox Star type 8010 the first computer came onto the market with graphical user interface and ethernet connection for the commercial use in 1981. In 1985 the Star technology became transfered into the project Elixir Desktop, a GUI for the PC. Apple used a GUI with the computer system "Lisa" in 1983. The GUI Visi On was released by Visi Corp PC especially for the IBM PC in 1984, Digital Research offered at the same time GEM for Intel/DOS systems. Few time later the X Window System was born at the MIT for UNIX related operating systems

IPX/SPX (Internetwork Packet eXchange, Sequenced Packet Exchange) is needed for the communication with older Novell NetWare servers up to version 4.x, after that as optional protocol for data transmission. It is a particularly efficient network protocol and designed for smaller networks.

Multi-Tasking serves for the almost parallel and time limited execute of program parts in an arbitrary number. This happens by the management of the operating system with the grant and revoke of system resources. Inside fast time switches in milli-seconds or with real time operating systems in nano-seconds the access is regulated.

Computer systems with multi-processors contains at least 2 CPUs. Through this the computer power rises almost proportionally with the number of processors. A part of the performance is needed for the management of the process allocation to coordinate the simultaneous access at shared memory. The operating system is able to distribute the computing load on several processors, named as SMP (symmetrical multi-processing). These processes can be executed parallel at the same time. Condition is the use of especially SMP optimized software. Examples of supporting operating systems are BeOS, Linux and Windows NT/2000 in the corresponding version depending on supported processor number.

The multi-user ability of a operating system makes it possible to let login and work several users at one computer at the same time. The ressoruces of a multi-user system can be used fully.

NetBEUI (NetBIOS Extended User Interface) is a network protocol developed by Microsoft which stands out primarily due to his performance for small networks but cannot be routed in networks.

PDA The Personal Digital Assistent as a small, handy digitally equipment takes over the functions of a memo pad and also for Internet services like WAP and e-mail. Even word processing and other applications are mobile usable.
POSIX The Portable Operating System for unIX specification serves the uniform use of the API and the development of compatible programs under different operating systems. It made it easier to port and run UNIX applications on different operating systems like Windows NT and others. Also under the different UNIX derivatives a uniform standard was created to protect in-house developments of individually companies. In addition, it guarantees the protection of done investments because applications remain transferably.

The Protected Mode is supported by all x86 processors since Intel 286. With this mode memory can be addressed up to 4 gbyte. The processing bandwith is 32-Bit, for compatibility reasons 16-Bit programs can be executed furthermore too. For this a virtual engine is required for the use of real mode programs like MS DOS programs under Windows 9 x/NT, which provides a exclusive 16-Bit environment.

Real mode is an operating mode which was supported before the Intel 286 CPU as the only available mode. It makes the absolute access to working memory and hardware possible. This mode can address up to 1 mbyte RAM, teh processing bandwith is 16-Bit. Example of one real mode operating system is MS-DOS without an Extender. With the Intel 286 CPU the protected mode become introduced, which makes a controlled access to the resources and memory protection possible.

The TCP/IP (Transmission Control Protocol, Internet Protocol) is the standard network protocol for the internet and large companies. Since 1982 it has replaced the previous protocol NCP (Network Control Protocol). At the moment with version 4 it supports a 32-Bit address range and in the near future with TCP/IP version 6 a bigger address range with 128-Bit address range.

Thread To accelerate programs on normal computers and multi-processor systems parallizable program code is distributed in so-called Threads, which can be passed on several CPUs or executed with little deferred time on one CPU. Through this the simultaneous write and printing of one or different documents within an application is made possible.

A Driver is a software which is allocated as software layer between the hardware layer and the application or operating system. Besides the communication between driver software as in the case of a file system encryption these can also be purely virtual. File systems, network protocols, RAM disk and the DOS box are such virtual devices under Windows. As a rule, driver software are primarily developed further with improved efficiency over the time often seen for mainboard chipsets. New characteristics like TwinView for graphics cards or a lower processor load for hard disks operations in the DMA mode are practicable.
So that an application can access the hardware about the API a call is send to the operating system. After check after permission of the request to the hardware driver the connection to the driver software is made. The direct communication between application and driver software to the hardware is considerably faster than indirect about system calls but carried out without supervisory authority or special protection. About the indirect call to the operating system and interfaces bugs are heavily to trace for the user. Unclear remains most whether the bug was caused itself by the application, the operating system or the driver software. Applications are usable by the uniform driver software interface with considerably lower overhead on a broader hardware basis. The applications has not t oinclude self programmed device drivers to use the hardware equipment. Driver software developers for hardware procducts can just do concentrate her work to the hardware communication under compliance of the operating system to driver software interface communication without the need of special adaptation to single programs. By the different interfaces of driver software for a platform like PowerPC to x86 cannot be ported without adapted source code to another operating systems (like Windows 9x driver for Windows NT), except the source code supports the same mechanism. It remains supplementary to mention that the special customization of applications to single hardware components further is made and definitely makes sense in some areas to reduce the bug vulnerability, obtain the highest possible performance or simply increase the stability. Examples are the optimize of older programs for the Pentium 4 instruction set support or the MacOS with closely developed applications by the same company as Apple. [ Also see Windows device driver models ]

WDM The Win32 Driver model was designed in 1996 of Microsoft to create a uniform standard for all future Windows driver software. Hardware manufacturers use these interface between application and kernel around to develop compatible driver software for the hardware, graphic card drivers excepted. As advantages have to be called new extensions like plug & play and the energy management for Windows NT 4.0. The uniform driver software for Windows 98 and Windows 2000 as well as a near system imbedding provide better performance and stability. The development overhead is lowered by the standard.