Sbg school of learning

Bus Bus in  Computer system is an electronic components that is used to carry data or instructions between different components of computer system. PCI Bus: The Peripheral Component Interconnect (PCI) bus produced by Intel in 1992 provided direct access to system memory for any connected hardware devices. This bus allowed multiple packets of information from different sources to travel down it simultaneously. Previously it was used to connect to the graphics card and this setup meant that information from the graphics card travelled through the bus along with any other information coming from a device connected to the PCI. When all the information arrived at the CPU, it had to wait in line to get time with the CPU. This system worked well for many years, but eventually the PCI bus could not keep up. The Internet and most software were more and more graphically oriented, and the demands of the graphics card needed priority over all other PCI devices. This is now ...

Chipset:   The PC has become so complex that even the most recent, powerful processors can’t do the entire job of managing the flow of data by themselves. The CPU has been given help in the form of the chip set, located nearby on the motherboard. The chip set traditionally consisted of two microchips, often referred to as the North Bridge and the South Bridge, that acted as the administrators to the CPU, or chief executive. The chip set bridged logical and physical gaps between the CPU and other chips, all the time watching and controlling the input and output of specific components. The exact function of the chip set is constantly changing. In 2003 AMD introduced the AMD Athlon 64 bit chip, where the CPU reclaimed some of the memory controller functions of the North Bridge. Intel later also adopted this architecture with their core i-series of processors.   But in all cases, the bridges determine what kinds of memory, processors, and other components can work with t...

Boot-Up Process: A PC cannot do anything useful unless it is running its operating system - software that acts as a supervisor for all its software applications. It sets the rules for using memory, drives, and other hardware devices on the computer. Before a PC can run the operating system, it needs some way to load it from disk into RAM. The way to do this is with the bootstrap – a small amount of code that is executed on startup or system boot. The bootstrap is aptly named because it lets the PC do something entirely on its own   without any outside operating system.   The boot-up sequence of events is as follows: 1. The computer loads the basic input/output system (BIOS) from ROM. The BIOS provides the most basic information about storage devices, boot sequence, security, Plug and Play (auto device recognition) capability and a few other items.   2. The BIOS triggers a test called a power-on self-test (POST) to make sure all the major components are functioni...

Brief   History of Internet Internet, a global network that connects other computer networks, together with software and protocols for controlling the movement of data. The Internet, often referred to as 'the Net', stems from a network called ARAPNET (Advanced Research Project Agency Network), which was initiated in 1969 by a group of universities and private research groups funded by the US Department of Defense. It now covers almost every country in the world. Its organization is informal and deliberately nonpolitical--its controllers tend to concentrate on technical aspects rather than on administrative control. Introduction to the Internet The connection of computers can form a network, this connection may be direct (by direct cabling) or indirect (dial-up). The benefit of connecting computers can exchange information and share resources such as application software, printers, files, databases or even other networks The interconnection of networks among ...

Scheduling Algorithms CPU scheduling deals with the problem of deciding which of the processes in the ready queue is to be allocated the CPU. In this section, we describe several of the many CPU-scheduling algorithms that exist.   First-Come, First -Served Scheduling This non-preemptive scheduling algorithm follows the first-in, first-out (FIFO) policy. As each process becomes ready, it joins the ready queue. When the current running process finishes execution, the oldest process in the ready queue is selected to run next. By far the simplest CPU-scheduling algorithm is the first-come, first-served (FCFS) scheduling algorithm. With this scheme, the process that requests the CPU first is allocated the CPU first. The implementation of the FCFS policy is easily managed with a FIFO queue . When a process enters the ready queue, its PCB is linked onto the tail of the queue. When the CPU is free, it is allocated to the process at the head of the queue. The run...

Scheduling Criteria Different CPU-scheduling algorithms have different properties, and the choice of a particular algorithm may favor one class of processes over another. In choosing which algorithm to use in a particular situation, we must consider the properties of the various algorithms. Many criteria have been suggested for comparing CPU-scheduling algorithms. Which characteristics are used for comparison can make a substantial difference in which algorithm is judged to be best. The criteria include the following: ·          CPU utilization : We want to keep the CPU as busy as possible. CPU utilization may range from 0 to 100 percent. In a real system, it should range from 40 percent (for a lightly loaded system) to 90 percent (for a heavily used system). ·          Throughput : If the CPU is busy executing processes, then work is being done. One measure of work is the number of processes compl...

CPU Scheduling CPU scheduling  is a process which allows one process to use the  CPU  while the execution of another process is on hold(in waiting state) due to unavailability of any resource like I/O etc, thereby making full use of  CPU . The aim of  CPU scheduling is to make the system efficient, fast and fair. Scheduling is a fundamental operating-system function. Almost all computer resources are scheduled before use. The CPU is, of course, one of the primary computer resources. Thus, its scheduling is central to operating-system design. CPU-I/O Burst Cycle The success of CPU scheduling depends on the following observed property of processes: Process execution consists of a cycle of CPU execution and I/O wait. Processes alternate between these two states. Process execution begins with a CPU burst. That is followed by an I/O burst, then another CPU burst, then another I/O burst, and so on. Eventually, the last CPU burst will end with a system reque...

Operating Systems  What is an OS – It is a control program that provides an interface between the computer hardware and the user. Part of this interface includes tools and services for the user.  “An operating system is a program that acts as an intermediary between a user of computer and computer hardware. The purpose of the OS is provide an environment in which the user can execute programs. The primary goal of an OS is thus to make the computer convenient to use. A secondary goal is to use the computer hardware in an efficient manner.” Computer Hardware – CPU, memory, I/O devices provide basic computing resources. System and Application Programs – Compilers, database systems, games, business programs, etc. define the ways the computing resources are used to solve the users problems. Operating System – Controls and coordinates the computing resources among the system and application programs for the users. End User – Views the computer system as a...