Chapter 1 The Big Picture 1 Computing Systems

Chapter 1 The Big Picture 1

Computing Systems Computing systems are dynamic entities used to solve problems and interact with their environment. They consist of devices, programs, and data. 2 2

Computing Systems Hardware - The physical elements of a computing system (printer, circuit boards, wires, keyboard…). Software - The programs that provide the instructions for a computer to execute. Data - Information in a form a computer can use. 3 3

Layers of a Computing System Communication Application Operating System Programming Hardware Information 4 4

Abstraction - A mental model that removes complex details. This is a key concept. Abstraction will reappear throughout the course – be sure you understand it! 5 5

Early History of Computing Abacus (2400 BC) An early device to record numeric values. Blaise Pascal (1623 -1662) Created a mechanical device to add, subtract, divide & multiply. Gottfried Wilhelm von Leibniz (1646 -1716) Created a mechanical device to perform all four whole number operations. Joseph Jacquard’s Loom (1801), the punched card 6 6

Early History of Computing Charles Babbage (1792 -1871) Difference Engine, Analytical Engine Augusta Ada Byron (Lovelace) Babage’s assistant Considered to be the first Programmer, q Invented the concept of the loop William Burroughs (1857 -1898) Adding Machine Herman Hollerith (1860 -1929) Electro-mechanical Tabulator 7

Early History of Computing Alan Turing (1912 -1954) Turing Machine - an abstract mathematical model Artificial Intelligence Testing Early computers launch new era in mathematics, physics, engineering and economics. Harvard Mark I (1939) ENIAC - Electronic Numerical Integrator and Calculator EDVAC - Electronic Discrete Variable Automatic Computer first machine with a stored program UNIVAC I - Universal Automatic Computer (1951) 8 7

First Generation Hardware (19511959) Vacuum Tubes Large, not very reliable, generated a lot of heat Magnetic Drum Memory device that rotated under a read/write head Card Readers Magnetic Tape Drives Sequential auxiliary storage devices 9 8

Second Generation Hardware (19591965) Transistor Replaced vacuum tube fast, small, durable, cheap Magnetic Cores Replaced magnetic drums information available instantly Magnetic Disks Replaced magnetic tape data can be accessed directly 10 9

Third Generation Hardware (1965 -1971) Integrated Circuits Replaced circuit boards smaller, cheaper, faster, more reliable Transistors Now used for memory construction Terminal An input/output device with a keyboard and screen 11 10

Fourth Generation Hardware (1971? ) Large-scale Integration Great advances in chip technology PCs, the Commercial Market, Workstations Personal Computers were developed as new companies like Apple and Atari came into being. Workstations emerged. 12 11

Parallel Computing and Networking Parallel Computing Computers rely on interconnected central processing units that increase processing speed. Networking With the Ethernet small computers could be connected and share resources. A file server connected PCs in the late 1980 s. ARPANET and LANs Internet 13 12

First Generation Software (1951 -1959) Machine Language Computer programs were written in binary (1 s and 0 s). Assembly Languages and translators Programs were written in artificial programming languages and were then translated into machine language. Programmer Changes Programmers divide into application programmers and systems programmers. 14 13

Second Generation Software (19591965) High Level Languages English-like statements make programming easier. Fortran, COBOL, Lisp are examples. High-Level Languages Assembly Language Machine Language 15 14

Third Generation Software (1965 -1971) n Systems Software q q q n utility programs, language translators, and the operating system, which decides which programs to run and when. Separation between Users and Hardware Computer programmers began to write programs to be used by people who did not know how to program. 16 15

Third Generation Software (19651971) Application Package Systems Software High-Level Languages Assembly Language Machine Language 17 16

Fourth Generation Software (1971 -1989) Structured Programming Pascal, C, C++ New Application Software for Users spreadsheets word processors database management systems 18 17

Fifth Generation Software (1990 present) Microsoft The Windows operating system, and other Microsoft application programs dominate the market. Object-Oriented Design Based on a hierarchy of data objects (i. e. Java). World Wide Web Allows easy global communication through the Internet. New Users Today’s user needs no computer knowledge. 19 18

Computing as a Tool Programmer / User Systems Programmer (builds tools) Applications Programmer (uses tools) Domain-Specific Programs User with No Computer Background 20 20