Computer Organization and Data Storage Lecture 3 PDF

Computer Organization and Data Storage Lecture 3 Objectives ❑ Define the Turing model of a computer ❑ Define the von Neuman model of a computer ❑ List the three subsystems of a computer ❑ Understand the role of each of three subsystems of a computer...

Computer Organization and Data Storage Lecture 3 Objectives ❑ Define the Turing model of a computer ❑ Define the von Neuman model of a computer ❑ List the three subsystems of a computer ❑ Understand the role of each of three subsystems of a computer 1.2 Objectives ❑ To list five different data types used in a computer. ❑ To describe how different data is stored inside the computer as bit patterns. ❑ To describe how integers are stored in a computer using unsigned format. ❑ To describe how integers are stored in a computer using sign-and-magnitude format. ❑ To describe how integers are stored in two’s 1.3 complement format. Objectives: ❑ To describe how real numbers are stored in a computer using floating-point format. ❑ To describe how text is stored in a computer using one of the various encoding systems. ❑ To describe how audio is stored in a computer using sampling, quantization, and encoding. ❑ To describe how images are stored in a computer using raster and vector graphics schemes. ❑ To describe how video is stored in a computer as images changing in time. 1.4  Please refer to your text book Chapter 1 Introduction Chapter 3 Data storage Chapter 5 Computer Organization Computer Organization Introduction A Turing machine is a hypothetical machine thought of by the mathematician Alan Turing in 1936. Despite its simplicity, the machine can simulate ANY computer algorithm, no matter how complicated it is! Above is a very simple representation of a Turing machine. It consists of an infinitely-long tape which acts like the memory in a typical computer, or any other form of data storage. The squares on the tape are usually blank at the start and can be written with symbols. In this case, the machine can only process the symbols 0 and 1 and " " (blank), and is thus said to be a 3- symbol Turing machine. Introduction At any one time, the machine has a head which is positioned over one of the squares on the tape. With this head, the machine can perform three very basic operations: Read the symbol on the square under the head. Edit the symbol by writing a new symbol or erasing it. Move the tape left or right by one square so that the machine can read and edit the symbol on a neighboring square. Just as a Turing machine reads a symbol from a tape and, according to that symbol and its internal state, writes another symbol, changes state and moves the tape, a von Neumann machine reads a symbol string from memory and according to the value of that string and the current state of its registers, writes another string to memory, changes the state of its registers and moves to read another memory location. Introduction Computers built on the Turing machine store data in their memory. Around 1944-1945, John Von Neumann proposed that, since program and data are logically the same, programs should also be stored in the memory of the computer. Computers built on the von Neumann model divide the computer hardware into three broad categories or subsystems: 1- central processing unit (CPU) 2- main memory 1.10 3- input/output subsystem Introduction 1.11 Computer Hardware (subsystems) Introduction 1.12 Computer Hardware (subsystems) Introduction Inside the System Unit 13 Introduction Computer Hardware The Motherboard Computer chip: A very small pieces of silicon or other semi-conducting material onto which integrated circuits are embedded Circuit board: A thin board containing computer chips and other electronic components Motherboard or system board: The main circuit board inside the system unit All devices must connect to the motherboard External devices (monitors, keyboards, mice, printers) typically connect by plugging into a port exposed through the exterior of the system unit Wireless devices connect through a transceiver or wireless networking technology (like Bluetooth) 15 The CPU Central processing unit (CPU): circuitry and components packaged together and connected directly to the motherboard Does the vast majority of processing for a computer Also called a processor; called a microprocessor when talking about personal computers Dual-core CPU: Contains the processing components (cores) of two separate processors on a single CPU Quad-core CPU: Contains 4 cores Typically different CPUs for desktop computers, portable computers, servers, mobile devices, etc. Often made by Intel or AMD 16 The CPU The central processing unit (CPU) performs operations on data. In most architectures it has three parts: an arithmetic logic unit (ALU), a control unit, and a set of registers, fast storage locations. 1.17 The CPU 1.18 The CPU CPUs today typically have 19 The CPU 20 The CPU Processing Speed CPU clock speed: One measurement of processing speed Measured in megahertz (MHz) or gigahertz (GHz) Higher CPU clock speed = more instructions processed per second Alternate measure of processing speed is the number of instructions a CPU can process per second Megaflops, gigaflops, teraflops Other factors (CPU architecture, memory, bus speed, amount of RAM, etc.) also affect the overall processing speed of a computer Benchmark tests: Can be used to evaluate overall processing speed 21  Assignment Prepare a comparison table between all Intel processors starting from 8086 in 1978 up to the latest (2022) Main Memory Main memory is the second major subsystem in a computer. Memory consists of a collection of storage locations, each with a unique identifier, called an address. Data is transferred to and from memory in groups of bits called words. If the word is 8 bits, it is referred to as a 1.23 Main Memory Memory refers to chip based storage RAM (random access memory): Computer’s main memory Consists of chips arrange on a circuit board called a memory module plugged into the motherboard Stores essential parts of operating system, programs, and data the computer is currently using Adequate RAM is needed to run programs Volatile: Contents of RAM is lost when the computer is shut off Most personal computers use DDR-RAM(Double Data Rate dynamic random access memory) MRAM and PRAM: non-volatile RAM under development 24 Main Memory Main Memory 1.25 Main Memory Address Space Memory units 1.26  Word Size and Cache Memory Word size: The amount of data that a CPU can manipulate at one time Typically 32 or 64 bits Cache memory: Special group of very fast memory chips located on or close to the CPU Level 1 is fastest, then Level 2, then Level 3 More cache memory typically means faster processing Usually internal cache (built into the CPU) Often some cache dedicated to each core; may also have some shared cache accessible by any core 27  Assignment Prepare a report about the different types of ROM (ROM – PROM – EPROM- EEPROM – Flash ) Prepare a report about the different types of RAM (SRAM – DRAM – SDRAM- RDRAM - DDRAM ) Main Memory Main Hierarchy 1.29 Cache Memory 1.30 Input/output System The third major subsystem in a computer is the collection of devices referred to as the input/output (I/O) subsystem. This subsystem allows a computer to communicate with the outside world, and to store programs and data even when the power is off. Input/output devices can be divided into two 1.31 broad categories: non-storage and storage Input/output System Input and output devices Subsystem Interconnection The previous sections outlined the characteristics of the three subsystems (CPU, main memory, and I/O) in a stand- alone computer. We now explore how these three subsystems are interconnected. The interconnection plays an important role because information needs to be 1.33 exchanged between the three Subsystem Interconnection Connecting CPU and Memory 1.34 Subsystem Interconnection Connecting I/O devices to the 1.35 buses  Subsystem Interconnection Bus Width, Bus Speed, and Bandwidth Bus: An electronic path over which data can travel Bus width: The number of wires in the bus over which data can travel Bus width and speed determine the throughput (or bandwidth) of the bus Bus width. Bandwidth :The amount of data that can be transferred by the bus in a given time period A wider bus can transfer more data at one time that a narrow bus 36 Data Storage Data types Data today come in different forms including numbers, text, audio, image, and video. Different Data Types 1.38 Data inside the computer All data types are transformed into a uniform representation when they are stored in a computer and transformed back to their original form when they are retrieved. The universal representation is called a bit pattern. A bit pattern Data inside the computer Storage of different data types Data inside the computer STORING NUMBERS A number is changed to the binary system before being stored in the computer memory However, there are still two issues that need to be handled: How to show the decimal point. 1.41 How to store the sign of the number. Data inside the computer STORING NUMBERS Fixed point representation of integers Data inside the computer Unsigned Representation An unsigned integer is an integer that can never be negative and can take only zero or positive values. Applications of unsigned integers Counting Addressing Storing other data types such as text, images, audio and video. Data inside the computer STORING NUMBERS Signed Integers can be represented using Sign-and-magnitude representation Two’s complement representation Two’s complement representation is the standard representation for storing integers in computers today. Sign-and-magnitude representation Data inside the computer STORING NUMBERS 1.45 Summary of integer Data inside the computer STORING TEXT A section of text in any language is a sequence of symbols used to represent an idea in that language. Numbers are treated separately, as we explained in the previous section, and symbols (., ?, :, ; , …, !) to represent punctuation. 1.46 Other symbols such as blank, newline, and Data inside the computer STORING TEXT Representing symbols using bit pattern 1.47 Data inside the computer STORING TEXT Number of symbols and bit 1.48 patterns Data inside the computer STORING IMAGES Images are stored in computers using two different techniques: raster graphics vector graphics. 1.49 Data inside the computer STORING IMAGES Some colors defined in True- Color 1.50 Data inside the computer STORING AUDIO An Audio Signal 1.51 Sampling An Audio Signal Data inside the computer STORING VIDEO Video is a representation of images (called frames) over time. A movie consists of a series of frames shown one after another to create the illusion of motion. In other words, video is the representation of information that changes in space (single 1.52 Summary and Discussion