Paper Name: Computer Organization And Architecture

Paper Name: Computer Organization and Architecturelogical terms” . A device that accepts data1, processes the data according to theinstructions provided by the user, and finally returns the results to the user andusually consists of input, output, storage, arithmetic, logic, and control units. Thecomputer can store and manipulate large quantities of data at very high speedThe basic function performed by a computer is the execution of a program. A programis a sequence of instructions, which operates on data to perform certain tasks. Inmodern digital computers data is represented in binary form by using two symbols 0and 1, which are called binary digits or bits. But the data which we deal with consistsof numeric data and characters such as decimal digits 0 to 9, alphabets A to Z,arithmetic operators (e.g. , -, etc.), relations operators (e.g. , , etc.), and many otherspecial characters (e.g.;,@,{,],etc.). Thus, collection of eight bits is called a byte. Thus,one byte is used to represent one character internally. Most computers use two bytes orfour bytes to represent numbers (positive and negative) internally. Another term, whichis commonly used in computer, is a Word. A word may be defined as a unit ofinformation, which a computer can process, or transfer at a time. A word, generally, isequal to the number of bits transferred between the central processing unit and themain memory in a single step. It ma also be defined as the basic unit of storage ofinteger data in a computer. Normally, a word may be equal to 8, 16, 32 or 64 bits .Theterms like 32 bit computer, 64 bit computers etc. basically points out the word size ofthe computer.1.3 VON NEUMANN ARCHITECTUREMost of today’s computer designs are based on concepts developed by John vonNeumann referred to as the VON NEUMANN ARCHITECTURE. Von Neumann proposedthat there should be a unit performing arithmetic and logical operation on the data.This unit is termed as Arithmetic Logic (ALU). One of the ways to provide instruction tosuch computer will be by connecting various logic components in such a fashion, thatthey produce the desired output for a given set of inputs. The process of connectingvarious logic components in specific configuration to achieve desired results is calledProgramming. This programming since is achieved by providing instruction withinhardware by various connections is termed as Hardwired. But this is a very inflexibleprocess of programming. Let us have a general configuration for arithmetic and logicalfunctions. In such a case there is a need of a control signal, which directs the ALU toperformed a specific arithmetic or logic function on the data. Therefore, in such asystem, by changing the control signal the desired function can be performed on data.1Representation of facts, concepts, or instructions in a formalized manner suitable forcommunication, interpretation, or processing by humans or by automatic means. Anyrepresentations such as characters or analog quantities to which meaning is or might beassigned

Paper Name: Computer Organization and ArchitectureAny operation, which needs to be performed on the data, then can be obtained byproviding a set of control signals. This, for a new operation one only needs to changethe set of control signals.But, how can these control signals by supplied? Let us try to answer this from thedefinition of a program. A program consists of a sequence of steps. Each of these steps,require certain arithmetic or logical or input/output operation to be performed on data.Therefore, each step may require a new set of control signals. Is it possible for us toprovide a unique code for each set of control signals? Well the answer is yes. But whatdo we do with these codes? What about adding a hardware segment, which accepts acode and generates termed as Control Unit (CU). This, a program now consists of asequence of codes. This machine is quite flexible, as we only need to provide a newsequence of codes for a new program. Each code is, in effect, and instruction, for thecomputer The hardware interprets each of these instructions and generates respectivecontrol signals,The Arithmetic Logic Unit (ALU) and the Control Unit (CU) together are termed as theCentral Processing Unit (CPU). The CPU is the moist important component of acomputer’s hardware. The ALU performs the arithmetic operations such as addition,subtraction, multiplication and division, and the logical operations such as: “Is A B?”(Where A and B are both numeric or alphanumeric data), “Is a given character equal toM (for male) or F (for female)?” The control unit interprets instructions and produces therespective control signals.All the arithmetic and logical Operations are performed in the CPU in special storageareas called registers. ‘The size of the register is one of the important consideration indetermining the processing capabilities of the CPU. Register size refers to the amount ofinformation that can be held in a register at a time for processing. The larger theregister size, the faster may be the speed o processing. A CPU’s processing power ismeasured in Million Instructions Per Second (MIPS). The performance of the CPU wasmeasured in milliseconds (one thousand of a second) on the first generation computers,in microseconds (one millionth of a second) on second-generation computers, and isexpected to be measured in Pico-seconds (one 1000th of a nano-second) in the latergenerations. How can the instruction and data be put into the computers? An externalenvironment supplies the instruction and data, therefore, an input module is needed.The main responsibility of input module will be to put the data in the form of signalsthat can be recognized by the system. Similarly, we need another component, which willreport the results in the results in proper format and form. This component is calledoutput module. These components are referred together as input/output (I/O)components. In addition, to transfer the information, the computer system internallyneeds the system interconnections. Most common input/output devices are keyboard,monitor and printer, and the most common interconnection structure is the Busstructure.

Paper Name: Computer Organization and ArchitectureAre these two components sufficient for a working computer? No, because input devicescan bring instructions or data only sequentially and a program may not be executedsequentially as jump instructions are normally encountered in programming. Inaddition, more than one data elements may be required at a time. Therefore, atemporary storage area is needed in a computer to store temporarily the instructionsand the data. This component is referred to as memory. It was pointed out by vonNeumann that the same memory can be used or storing data and instructions. In suchcases the data can be treated as data on which processing can be performed, whileinstructions can be treated as data, which can be used for the generation of controlsignals.The memory unit stores all the information in a group of memory cells, also calledmemory locations, as binary digits. Each memory location has a unique address andcan be addressed independently. The contents of the desired memory locations areprovided to the central processing unit by referring to the address of the memorylocation. The amount of information that can be held in the main memory is known asmemory capacity. The capacity of the main memory s measured in Kilo Bytes (KB) orMega Bytes (B). One-kilo byte stands for 210 bytes, which are 1024 bytes (orapproximately 1000 bytes). A mega byte stands for 220 bytes, which is approximatelylittle over one million bytes. When 64-bit CPU's become common memory will start to bespoken about in terabytes, petabytes, and exabytes. One kilobyte equals 2 to the 10th power, or 1,024 bytes. One megabyte equals 2 to the 20th power, or 1,048,576 bytes. One gigabyte equals 2 to the 30th power, or 1,073,741,824 bytes. One terabyte equals 2 to the 40th power, or 1,099511,627,776 bytes. One petabyte equals 2 to the 50th power, or 1,125,899,906,842,624 bytes. One exabyte equals 2 to the 60th power, or 1,152,921,504,606,846,976 bytes. One zettabyte equals 2 to the 70th power, or te: There is some lack of standardization on these terms when applied to memory anddisk capacity. Memory specifications tend to adhere to the definitions above whereasdisk capacity specifications tend to simplify things to the 10th power definitions(kilo 103, mega 106, giga 109, etc.) in order to produce even numbers. Let us summarize the key features of a von Neumann machine. The hardware of the von Neumann machine consists of a CPU, which includesan ALU and CU. A main memory system An Input/output system The von Neumann machine uses stored program concept, e.g., the program anddata are stored in the same memory unit. The computers prior to this idea used

Paper Name: Computer Organization and Architectureto store programs and data on separate memories. Entering and modifying theseprograms were very difficult as they were entered manually by setting switchesand plugging and unplugging. Each location of the memory of von Neumann machine can be addressedindependently. Execution of instructions in von Neumann machine is carried out in asequential fashion (unless explicitly altered by the program itself) from oneinstruction to the next.The following figure shows the basic structure of von Neumann machine. A vonNeumann machine has only a single path between the main memory and controlunit (CU). This feature/ constraint is refereed to as von Neumann bottleneck.Several other architectures have been suggested for modern computersvon Neumann Machine.1.4 Attributed to John von Neumann Treats Program and Data equally One port to Memory . Simplified Hardware "von Neumann Bottleneck" (rate at which data and program can get into theCPU is limited by the bandwidth of the interconnect)HISTORY OF COMPUTERSBasic information about the technological development trends in computer in the pastand its projections in the future. If we want to know about computers completely thenwe must start from the history of computers and look into the details of varioustechnological and intellectual breakthrough. These are essential to give us the feel ofhow much work and effort has been done to get the computer in this shape.The ancestors of modern

Paper Name: Computer Organization and Architecture SYLLABUS 1. Introduction to Computers Basic of Computer, Von Neumann Architecture, Generation of Computer, . “Computer System Architecture”, John. P. Hayes. 2. “Computer Architecture and parallel Processing “, Hwang K. Briggs. 3. “Computer System Architecture”, M.Morris Mano.