Class 11 Computer Science Chapter 5 Notes

• Describe Van Neumann’s Stored Program Computer.
• Describe most important components of modern stored program machine.
• Describe Bus Interconnection and explain three types of bus.
• Describe Input / Output Unit.
• Explain the TWO ways / methods of transferring data from the peripherals into the computer.
• Explain CPU Registers.
• Explain different types of operations performed by computer.
• Define Instruction Format ? Explain various Instruction Code Formats in use.
• Explain Fetch-Decode-Execute Cycle with diagram.
• Define Software ? Differentiate between Application Software and System Software.
• Explain Main Functions of Operating System.
• Describe Machine Code, Assembler, Assembly Language, Compiler, Source Code and Object Code and Interpreter.
• Differentiate between Compiler and Interpreter. 
• Main Memory: The stored program computer has another very important component that is use to store program and data while these are being executed. This unit is commonly known as the Main Memory of the computer. Sometimes we also call it the working area of the computer. I/O Unit: This handles the processor's communication with its peripherals. For example, Disc drive, monitor, printer etc. There are registers to hold the data coming in or going out and a peripheral device selection unit which determines which interface to send the data to. As the data and instructions should be in the memory before the computer can start executing it so to place data and instructions in the memory this stored program computer also has some I/O devices. Bus Interconnection: This is another important component of the basic architecture and this component is used to connect different parts of the computer together. The CPU is centrally located on the motherboard. Since the CPU carries out a large share of the work in the computer, data pass continually through it. The data come from the RAM and the units (keyboard, drives etc.). After processing, the data is send back to RAM and the units. The CPU continually receives instructions to be executed. Each instruction is a data processing order. The work itself consists mostly of calculations and data transport: On large machines, CPUs require one or more printed circuit boards. On personal computers and small workstations, the CPU is housed in a single chip called a microprocessor. Two typical components of a CPU are: 
• The arithmetic logic unit (ALU): The ALU part of a computer that performs all arithmetic computations, such as addition and multiplication, and all comparison operations. The ALU is one component of the CPU. The control unit (CU), which extracts instruction from memory and decodes and executes them, calling on the ALU when necessary. Main Memory: As mentioned earlier, a computer executes a program in its main memory, which is another very important component of the stored program computer. A computer cannot work without having some kind of main memory in it. In these section, we will learn more about different types of memories used in a computer and their working. Mostly the modern computer memory is built in the form of a chip of a semi conductor material. It is built in the form of thousand or even millions of cells each capable of storing a bit i-e a 0 or 1. This is shown in figure 5.3. below.