Digital Information Technology

1. Digital Information Technology Introduction

2. Learning Objectives • Identify the major hardware components of a computer system • Describe the evolution of computer processor technology • Differentiate the various types of input and output technologies and their uses • Identify the characteristics of computer memory and memory capacity terminology • Describe the design and functioning of the central processing unit • Discuss the concept of digital technology and how it impacts storage and processing for character data, numbers, and various forms of multimedia

3. Introduction • E-commerce is enabled by a wide range of digital information technologies including computer hardware, software, databases, networks, the Internet/Web, and various forms of multimedia • In this discussion we focus on the components of a computer system, and how these components function, to gain an understanding of the capabilities and limitations of digital information technology • A computer system consists of the following: • Central processing unit (CPU) • Primary storage • Secondary storage • Input technologies • Output technologies • Communication technologies

4. Computer System Components

5. Processor Technology Evolution • Computer processing hardware technology has evolved quite dramatically in the past 60+ years • The generations of hardware technology include: • 1st generation – Vacuum tubes (1946-1956) • 2nd generation – Transistors (1957-1963) • 3rd generation – Integrated circuits (1964-1979) • 4th generation – Ultra-large-scale integrated circuits (1980-present) • 5th generation – Massively parallel processing • What are the trends associated with the evolution of hardware technology?

6. Processor Speed Terminology • As the speed of computer processors, data access devices, and data transmission continues to increase, new terminology is required to compare current capabilities with older technologies • Time in a computer environment is represented in fractions of a second • The following are common measures of time: • Millisecond = 1/1000 second • Microsecond = 1/1,000,000 second • Nanosecond = 1/1,000,000,000 second • Picosecond = 1/1,000,000,000,000 second

7. Input and Output Devices • Input and output (I/O) devices enable human-computer interaction (HCI) • Input devices enable human data and actions to be converted into a computer-understandable format • Examples include a keyboard and a mouse • Output devices translate computer representations of data into a human-understandable format (text, images, sound, etc.) • Examples include monitors and printers • Input and output devices have traditionally been physical devices, but the trend is toward more virtual I/O devices

8. Computer Memory • Storing characters, numbers, images, and other multimedia files for organizations and individuals requires a massive amount of computer memory • Luckily, as computer hardware technology has evolved, so has the computer memory capacity required to support new applications • Example secondary storage devices include internal computer hard drives, external hard drives, CD/DVD, flash memory devices, and cloud-based storage services • As storage requirements have continued to increase, new terminology is required to describe digital storage capacity

9. Hierarchy of Memory Capacity • Kilobyte • Approximately one thousand bytes • A kilobyte is actually 1024 bytes (why?) • Megabyte • One million (106) bytes • Gigabyte • One billion (109) bytes • Terabyte • One trillion (1012) bytes • Petabyte • One quadrillion (1015) bytes • Exabyte • One quintillion (1018) bytes

10. The Central Processing Unit • The central processing unit (CPU) performs the actual computation inside any computer • The CPU is a microprocessor made up of millions of microscopic transistors embedded in a circuit on a silicon wafer (or chip) • The CPU and all components of a computer system process and store data using digital technology • What is the unique characteristic of “digital” technology?

11. How the CPU Works

12. Digital Technology • Today’s computers are based on integrated circuits (chips), each of which includes millions of subminiature transistors • Each transistor can be in either an “on” or “off” position • The “on-off” states of transistors are described using binary number system where each binary digit, or bit, has a value of either 1 or 0 • This digital concept enables the storage and processing of characters, numbers, and various forms of multimedia

13. Character Representation and Processing • A sufficient number of bits to represent specific characters – letters, numbers, and special symbols – is known as a byte, usually 8 bits • Because a bit has only two states, 0 or 1, the bits comprising a byte can represent any of 28, or 256, unique characters • The two most commonly used coding schemes are: • For microcomputers - the American National Standard Code for Information Interchange (ASCII), pronounced “ask-ee” • For mainframe computers – the Extended Binary Coded Decimal Interchange Code (EBCDIC), pronounced “ebsa-dick” • ASCII and EBCDIC are sufficient for English and Western European languages but are not large enough for Asian and other languages that use different alphabets

14. Number Representation and Processing • Numbers in a computer are stored and processed using binary (base 2) representations • Why? • Humans store numbers and do mathematical computations using a decimal representation (base 10) • Why? • The ALU in a CPU can perform basic computations such as add, subtract, multiply, divide, compare, and determine whether a number is positive, negative, or zero • How does a computer perform these numerical processes?

15. Image Representation and Processing • Pictures are represented by a grid overlay of the picture • Each dot on a screen, or pixel, can display one color • More pixels per square inch improve the picture clarity, but also take more storage space and require more time to download

16. Image Representation and Processing (cont.) • Each pixel can be displayed in a wide range of colors by varying the intensity of red, green and blue displayed for each pixel • Two common image formats are: • Graphics Interchange Format (GIF), 8 bits per pixel, 256 colors • Joint Photographic Experts Group (JPEG), 24 bits per pixel, 16.7 million colors

17. Video Representation and Processing • How is video storage and processing different from image storage and processing? • Video files are digitally stored as a series of interrelated still images • The file sizes vary depending on format, frame size, and frame rate (frames per second, fps) • A typical fps rate is about 15-30, fast enough to fool the human eye and make the series of still images appear as natural movement

18. Audio Representation and Processing • Every sound (wave) can be described by two characteristics – amplitude (loudness) and frequency (pitch) • Digital recording measures the sound’s characteristics at discrete moments in time • The conversion method from analog to digital affects the sound quality and the file size, it has three components: • Sampling rate – number of measurements in a period of time (KHz) • Sampling resolution – precision in measuring the sound within each sample (8-bit, 16-bit, etc.) • Channels – mono or stereo • For example, a telephone is 8KHz, 8-bit, mono; and a CD is 44KHz, 16-bit, stereo