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An Introduction to Computers August 12, 2008 Mrs. C. Furman.

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Presentation on theme: "An Introduction to Computers August 12, 2008 Mrs. C. Furman."— Presentation transcript:

1 An Introduction to Computers August 12, 2008 Mrs. C. Furman

2 4 Tasks of a Computer Input Data – keyboard, mouse, scanner, microphone, digital camera, CD-RW/DVD drive, and disk drive. Store Data – integrated circuits. Process Data – CPU, where decisions are made. Output Data – monitors, printers, CD- RW’s, disk drives and memory keys store data and speakers.

3 CPU Arithmetic Logic Unit, which can perform arithmetic and logic operations Executes instructions fast. Speed is determined by the computer’s clock rate. Clock Rate - measured in megahertz (MHz, million cycles per second) and gigahertz (GHz, billion cycles per second)

4 Memory ROM: Read Only Memory – most basic operations RAM: Random Access Memory – primary storage or main memory – data and instructions are temporarily stored RAM can be written to secondary storage. Secondary Storage – floppy disk, hard disk, memory key, or CD- RW.

5 Programs Application Software –Word, powerpoint, games… Operating System Software – OS – run automatically when the computer is turned on and is used to control processing and peripherals, run application software and control input and output. –Windows, Mac OS X Tiger, Unix, and Linux

6 Programming Languages A set of words, codes and symbols that allow a programmer to give instructions to the computer. Low – level and High – level programs…

7 Low – Level Languages Machine language – first generation language. –Consists of 0’s and 1’s Assembly language –Same instructions and structures as machine language –Uses meaningful names or abbreviations instead of numbers. –Second generation language.

8 High-Level Languages Third generation languages Developed in late 1950s English-like instructions Easier to use than machine language Fortran, Pascal, C, C++, Java Compilers – program that convert high-level language into machine language. Interpreter – also translates the program but does it line by line, executing as they go.

9 How is Data Stored? Data – computer representation of something in the real world. Circuits – 2 states ON /OFF Imagine 2 light bulbs / 2 switches, what are the possible combinations? OFF / OFF OFF / ON ON / OFF ON / ON

10 What about 3 lights? How many combinations? What about 8 lights?

11 Apply to the computer… Use a special number system: Binary number system. Decimal Number System: base 10, digits 0 – 9. (Our number system) Binary Number System: base 2, digits 0 and 1. 0 represents off (false), 1 represents on (true). A single binary digit is called a bit.

12 Converting Binary to Decimal Decimal Numbers: 7403 = 7 x1000 + 4x100+ 0x10 + 3 x 1 3x10 0 = 3 0x10 1 = 0 4x10 2 = 400 7x10 3 = 7000 7403

13 Same process as previous slide, but base 2 8 bits in 1 byte: 1011 0110 0x2 0 = 0 1x2 1 = 2 1x2 2 = 4 0x2 3 = 0 1x2 4 = 16 1x2 5 = 32 0x2 6 = 0 1x2 7 = 128 Binary to Decimal Total: 182

14 8 bits = 1 byte What’s the number of combinations in 1 byte? What numbers can be represented with 1 byte?

15 Examples a. 1111 0000 b.1010 1010 c.1100 1100 d.0011 0011

16 Converting Decimal to Binary Binary Is base 2 We multiply to go from binary to decimal. We divide to go from decimal to binary. Right most digit tells even or odd. 1 – even 0 – odd.

17 Convert Decimal to Binary a. Convert 210 to binary. b.151

18 Hexadecimal Hexadecimal: Used to represent 4 binary digits. 1111 = 15 and 0000 = 0, so it is base 16. Digits 0 – 9 plus A – F A:10, B:11, C:12, D:13, E:14, F:15

19 Hexadecimal to decimal 1f 15x16 0 = 15 1x16 1 = 16 31

20 Change from Hexadecimal to Binary and Decimal 0 A 19 1E

21 Octal Octal is base 8 – digits 0 - 7 Convert 1047 8 to decimal 1047 7x8 0 = 7 4x8 1 = 32 0x8 2 = 0 1x8 3 = 512 = 551

22 What is the decimal equivalent? 111 2 345 8 2C 16


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