Every time a computer is turned on a monitor program is loaded from the secondary memory into main memory, which takes control of the computer and provides an interface to interact. Steps involved in booting process of a general OS : Basic Input Output System (BIOS) is stored in ROM, which capable of doing I/O
The objectives of an operating system are : Providing the ‘user-friendly’ interface so that the user need not bother about the underlying hard-ware. The commands given by user in an natural language are interpreted by the operating system, which in turn uses the hardware to get the required task done. Creating an environment for other
When the system is switch on, the operating system is automatically loaded into the main memory and it takes control of the computer system. The operating system provides an interface to the user for interaction with the machine by way of managing files, executing a program, or printing an output etc. The software running on
An interpreter is a program which reads and executes the source code program line by line. It does not translate the source code into machine code. Therefore, an interpreter is also called program execution environment. The designer of an interpreter goes through the source language, and makes a list of the the operations required to
There are four ways a computer system communicate with I/O devices. Direct control Programmed I/O Interrupt driven I/O Direct memory access Direct control : Old and obsolete technique. CPU interact directly with I/O devices with the help of dedicated program. Processing is extremely slow. Programmed I/O : CPU and I/O devices communicates through ‘Device Status
Principle of ‘locality of reference‘ : This principle suggests that at any given time, the CPU will be accessing memory in a localized region of memory. When the instruction is found in the cache, the transaction is called a hit else a miss. When cache memory sits along side the main memory then the architecture
A CPU executes an instruction store in the main memory of the computer. An instruction usually consists of two parts: Op-code (Operation to be performed) and operands (on which operation to be performed ( can be address or data itself)). CPU clock controls the timing of each operation. The length of time taken to go
A bus is a group of current-conducting wires over which data is transferred from one device to another. Their types are : Data bus : Transfers data Size is generally proportionate to CPU power. e.g. 64 bit CPU will have 64 bit wide bus. Generally bidirectional. Address bus : Carries the address of the device.
The main components of the CPU are– control unit (CU), arithmetic nd logical unit (ALU) and a set of registers. Control Unit : Responsible for controlling the movement of data and instructions in and out of the memory and the CPU. Decodes the fetched instruction and initiates the desired operation to be performed by the
A modern computer have four main components : Memory : Primary( is a semiconductor memory, volatile e.g. RAM) and Secondary (non-volatile auxiliary memory e.g. Hard-disk) memories. Input unit : e.g. Keyboard, mouse. Central Processing Unit (CPU). Output Unit. e.g. Monitor, Printer.