Chapter 3 Computer Hardware II A Brief History

Chapter 3 Computer Hardware

II. A Brief History of Computer Hardware Without computers many technological achievements would not have been possible: v. Counting with fingers/toes v. Blaise Pascal, 1642 – invented the first mechanical adding machine 2

A Brief History of Computer Hardware v. Herman Hollerith – Hollerith’s Punch Card system to record census data in late 1880’s; 1911 – merged with competitor to form IBM v. ENIAC (Electronic Numerical Integrator and Calculator), 1946 – the world’s first electronic digital computer 3

II. A Brief History of Computer Hardware v 1950’s – Transistors were invented and replaced tubes v 1958 – Integrated Circuit (“chip”) was invented v 1970’s – 1980’s v. Further miniaturization of circuits v. Apple Computer and IBM PC 4

III. Types of Computer Systems v. Computers come in a variety of sizes, shapes, and computing capabilities – v. Mainframes v. Midrange (obsolete due to powerful microcomputers) v. Microcomputers 5

IV. Microcomputer Systems (Personal Computer) The most important category for businesses and consumers, exceeds the power of many mainframes v. Workstations – support mathematical and graphical demands v. Network Servers – support telecommunications and resource sharing v. Computer Terminals – any device that allows access to a computer 6

IV. Microcomputer Systems (Personal Computer) v. Network Computers – designed specifically for use with networks and the Internet; low TCO (total cost of ownership) v. Information Appliances – Web-enabled devices for accessing information from anywhere – cell phones, PDAs, handheld PCs 7

Corporate PC Criteria v. Why laptops instead of desktops? v. Why would a change in OS be disruptive? v. What are the strengths vs. risks of cabled vs. wireless PCs? 8

V. Midrange, Mainframe, and Supercomputer Systems v. Midrange Systems – popular as Network Servers; disappearing due to microcomputers v. Mainframe Systems – large, fast, and powerful, used for high transaction processing and complex computations; used by corporations and government agencies v. Supercomputers – extremely powerful, extremely high speeds and massive numeric computations 9

V. Midrange, Mainframe, and Supercomputer Systems v. The Next Wave of Computing – minisupercomputers; connecting all the power of unused desktops in an organization v Distributed (Grid) Computing – parallel computing over a network v. Advantages – purchase nodes as a commodity, economies of scale v. Disadvantages – untrustworthy calculations, lack of centralized control 10

The Computer System 11

VII. Moore’s Law v Moore’s Law 1965 – the number of transistors on a chip will double every 18 -24 months – essentially, the power or speed of a computer will double every 18 -24 months v. The Price would halve in that same time, which has also proven to be true v. Recent statistics indicate this time has decreased to 12 months 12

Section 2 Computer Peripherals: Input, Output, and Storage Technologies Peripheral - a generic name for all input, output, and secondary storage devices not part of the CPU (basically, what is connected to the outside of the computer) 13

II. Input technologies v. Input Devices – keyboards, mice, light pens, trackballs, touch screens v. Speech Recognition Systems – understands spoken commands/words v. Discrete Speech Recognition – speak each word separately v. Continuous Speech Recognition – recognizes conversationally-paced speech v. Speaker-Independent Voice Recognition – understands speech from a voice it has never heard before 14

II. Input technologies v. Optical Scanning – converts text or graphics to digital input for direct entry of source documents v. Other Input Technologies v. Magnetic Stripe – on credit cards v. Smart Cards – contain an embedded chip v. Digital Cameras v. Magnetic Ink Character Recognition (MICR) – used in banking industry 15

Forget the ATM: Deposit Checks Without Leaving Home v. What does federal Check 21 Act allow? v. What is the concern of consumers remotely depositing checks? v. What basic security is provided? v. What limits/restrictions are placed on the consumers? 16

IV. Storage Tradeoffs 17

IV. Storage Tradeoffs v. Direct and Sequential Access v. Direct Access and Random Access are the same concept; locate an address on the storage device and go directly to that location for data access v. Sequential Access – All tape devices are accessed serially – device must be read one record at a time from the data until the desired data is found 18

VI. Magnetic Disks – Hard drives are the most common form of secondary storage v RAID (Redundant Arrays of Independent Disks) Storage – interconnected groups of hard drives - fast speeds and fault tolerant (redundant backups) 19

V. Semiconductor Memory v RAM (Random Access Memory) – volatile, may be read and over-written v ROM (Read Only Memory) – non-volatile, may be read but not over-written or erased; PROM and EPROM may be reprogrammed v Flash (Jump) Drives – solid-state memory 20

IV. Storage Tradeoffs v. Computer Storage Fundamentals v Binary Representation – Two-state, on/off, +/-, 0/1 v Bit – Binary digit, 0/1 v Byte – Grouping of bits (typically 8 bits/byte), represents a single character v ASCII – formalized code determining what byte values represent which character v Storage capacities – kilobytes (KB), megabytes (MB), gigabytes (GB), terabytes (TB) 21

Representing characters in bytes 22

VII & VIII. Magnetic Tape & Optical Disks v. Magnetic Tape – slow speeds, but inexpensive for large amounts of backups v. Optical Disks – CD-ROM, CD-R, DVD-R (cannot be erased or re-written); CD-RW, DVD-RW (may be erased or re-written) 23

VII. Radio Frequency Identification (RFID) RFID – for tagging and identifying mobile objects (store merchandise, postal objects, sometimes living organisms); provides information to a reader when requested v. Passive – no power source, derives power from the reader signal v. Active – self-powered, do not need to be close to the reader v. RFID Privacy Issues – may be used as spychips; gathers sensitive information about an individual without consent 24