COMBINATION OPERATING SYSTEMS

As presented here, different types of operating systems are optimized, or at least largely geared toward serving the needs of certain specific environments. In practice, however, a given environment may not exactly fit any of the described molds. For instance, both interactive program development and lengthy simulation are often encountered in university computing centers. For this reason, some commercial operating systems provide a combination of the described services.

For Example, a time-sharing system may support interactive user while also incorporating a full-fledged batch monitor. This allows computationally intensive non interactive programs to be run concurrently with interactive programs. The common practice is assign low priority to batch jobs and thus to exccute batched programs only when the processor would otherwise be idle. In other words, batch processing may be used as a filter to improve processor utilization while accomplishing a useful service of its own. Similarly, some time-critical events, such as receipt and transmission of network data packets, may be handled in real-time fashion on systems that otherwise provide time-sharing services to their terminal user.  

SERIAL PROCESSING

In theory, every computer system may be programmed in its machine language with no systems software support. Programming of the “bare machine” was customary for early computer systems. A slightly more advanced version of this mode of operation is common for the simple evaluation boards that are sometimes used in introductory microprocessor courses. Programs for the bare machine can be developed by manually translating sequences of instructions into binary or some other code whose base is usually an integer power of 2. Instruction and data are the entered in to the computer by means of console switches or, perhaps, through a hexadecimal keyboard. Program are started by loading the program are obtained by examining the contents of the relevant registers and memory locations. Input/output devices. If any, must be controlled by the executing  program directly, say, by reading and writing the related I/O ports. Evidently, programming of the bare machine result in low productivity of both users and hardware. The long and tedious process of program and data entry practically precludes execution of medium and large programs in such an environment.

The mechanics of development and preparation of programs in such environments are quite slow and cumbersome due to serial execution of programs and to numerous manual operations involved in the process. In a typical sequence, the editor program is loaded to prepare the source code of the user program. The next step is to load and execute the language translator and provide it with the source code of the user program. When serial input devices such as card readers are used, multiple-pass language translators may require the source code to be repositioned for reading during each pass. If syntax errors are detected, the hole process must be repeated from the beginning. Eventually, the object code produced from the syntactically correct source code is loaded and executed. If run-time errors are detected, the state of the machine can be examined and modified by means of console switches or with the assistance of a program called a debugger.

The described mode of operation was used initially in the late fifties, but it was also common in low-end microcomputers of the early eighties with cassettes as I/O devices.

In addition to language translators, systems software includes the loader and possibly the editor and debugger programs. Most of these programs use input/output devices and thus must contain some code to exercise those devices.

While a definite  improvement over the bare-machine approach, this mode of operation is obviously not very efficient. Running the computer system may require frequent manual loading of programs and data. This results in low utilization of system resources. User productivity, especially in multiuser environments, is low as users await their turn at the machine. Even with such tools as editors and debuggers, the program development is very slow and is ridden with manual program and data loading.

EVOLUTION OF OPERATING SYSTEMS

An Operating system may process its workload serially or concurrently. That is, resourses of the computer system may be dedicated to single program until its completion, or they may be dynamically reassigned among a collection of active programs in different stage of execution. Because of their ability to execute multiple programs in interleaved fashion, such operating systems are often reffered to as multi programming systems exist. In order to motivate the need for the types of services that each of these varieties provide, we briefly and informally sketch the evolutionary path of operating-system development. In particular, we describe serial processing, batch processing, and multi programming. No specific dates are attached to some of the events because we are interested in the progression of ideas and not in attempting to chart the history of oprating systems. Moreover, much of the historical development of operating systems for mainframes was first retraced by minicomputers and then again by microcomputers and personal computers. Thus many of the concepts and ideas recur are applicable to different systems at deferent times.

The mechanics of program execution and brief sketch of the process of program development, namely, the edit-compile-execute cycle, are described for each type of operating system. While execution of programs is an essential activity in all computer systems, productivity of program preparation is important only in program-development environments, such as university computing centers.

Brainware

Brainware is the people who make the program or simply use the program. Users can be categorized as follows: operators, programmers, systems analysts, and administrators

The relationship between the software and hardware computer user can be described as follows:
Computer users: Operator, Programmers, systems analyst, administrator
Software Application: Group of word processing, database, Table Processing, Browser and others.
Programming Languages​​: English Group low-level, high-level languages ​​such as Basic, Fortran, Cobol, FoxPro and so on.
Operating systems, examples of DOS, Unix Windows, Linux and so on.
Hardware: Equipment input, processor, storage and output devices.
Software users to operate the computer hardware work ordered

Know the Internet

Indeed, what is the internet? Was originally a computer network that was pioneered by DARPA (Defense Advance Research Project Agency), research institutes U.S. Department of Defense

Principles of Computer Security

Computer systems are usually designed to perform a specific function and provide essential services and important for an organization . The computer system is part of a company . As in the rules , we need to protect the system from attack or disruption that is part of the company's capital protection . Steps taken to prevent disruption or failure of a security measure . These actions include checking the validity of input data , and the provision of fire-resistant storage for media and protect the data that is in it . Encrypting data in the communication network is an example of a security measure .Threats can come from everywhere, some of them obvious , some not. Unavoidable , computer power supply can be interrupted at any time , especially in bad weather during the rainy season . Programs can be exposed to viruses or bugs are not known .

Bluetooth , the technology back to life

Be helpful to know the history of the early Bluetooth before membahsnya further . Bluetooth name originated from a prestigious project promoted by the international giant companies engaged in telecommunications and computers , including Ericsson , IBM , Intel , Nokia and Toshiba . With the code name of Bluetooth , the project started in 1998 because it was inspired by a Viking King ( Denmark ) were named Herald Blatand . The Herald Blatand ruling king in the 10th century and controlled most of the Danish and Scandinavian region at that time . Due to the vast area of ​​his power , the king 's finance Blatand Herald scientists and engineers to build a metamorphosis tech project that aims to control the forces of the tribes in the Scandinavian area remotely . Then for menhormati it , which means that Blatand Bluetooth ( in English ) project is named .

VLAN Trunking Protocol ( VTP )

One of the switches is the ability to provide a Virtual LAN ( VLAN ) . It begins with the need for port grouping by function or business needs . Thus the need for a port belonging Engineering , Accounting belonging to another .The reason was that due to flooding . Switch will forward broatcast to all ports . However, by using a VLAN , port group so that we can broadcast from a port in VLAN 1 is only sent to the ports in the VLAN .