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Observe Yourself or -5. Turn off communication devices. Dress properly. Module 3 Processing & memory. Learning Objective. After completing this module, students will be able to: Explain how data is encoded to computer. Discuss components and characteristics of the system unit.
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Observe Yourself or -5 • Turn off communication devices Dress properly
Learning Objective • After completing this module, students will be able to: • Explain how data is encoded to computer. • Discuss components and characteristics of the system unit. • Describe how CPU processes an instruction. • Name various types of memory
Binary • Topic • Data representation • Measuring capacity • Coding scheme • Parity bit
Human Language • Number 0-9 • Character A-Z • Voice • Picture
Digital Data Representation • Digital computers can understand only states, • and • and • The 0s and 1s used with digital devices can be represented in a variety of ways • Open or closed circuit • Absence or presence of an electronic charge • Absence or presence of a magnetic spot
Bit • Regardless of their physical representations, these 0s and 1s are commonly referred to as bits (binary digits). • A bit is the smallest unit of data that a digital computer can recognize, so the input you enter stored on you PC are all just .
bit by itself typically represents only a fraction of a piece of data. Consequently, bits are usually grouped together to form letters and other characters, documents, program files, graphics files, and more. • Eight bits grouped together are collectively referred to as a byte. • Byte terminology is frequently used in a variety of computer contexts. For example, document size and storage capacity are measured in bytes, based on the amount of data that is contained in the document or that can be stored on the storage medium. • The size of any item such as program, written document, photo file, music file is measured in bytes.
Prefix for larger amounts of data • KB • MB • GB • TB • PB • EB • ZB • YB
Coding System • Number • Text • Graphics • Audio • Video
Representing Numerical Data • Numbering system
Data Representation • Decimal System • Use 10 symbols (0,1,2,3,4,5,6,7,8,9) • For human understanding • Binary System • : the basic unit of computing • Two number system • Use 2 symbols (0 and 1) • Electrical current being off (0)and on (1) • All data and program instructions in the computer are represented as binary
Convert Decimal to Binary • Choose a method of conversion • Comparison with descending powers of two and subtraction • Short division by two with remainder 9
Examples of decimal & binary number • The binary number 1001 • 1*23 + 0*22 + 0*21 + 1*20 • 9 in decimal system
Coding Schemes for Text • Binary coding schemes assign a unique binary code to each letter • Extended Binary Coded Decimal Interchange Code • For mainframe • 8 bits for a character • Combination of 28 =256 characters • American Standard Code for Information Interchange • For microcomputer • Requires 7 or 8 bits per character, depending on the version • 8 bits for a character • Combination of 28 = 256 characters
Problem before • Fundamentally, computers just deal with numbers. • They store letters and other characters by assigning a number for each one. • Before Unicode was invented, there were hundreds of different encoding systems for assigning these numbers. • No single encoding could contain enough characters • These encoding systems also conflict with one another. • That is, two encodings can use the same number for two different characters, or use different numbers for the same character. • Any given computer (especially servers) needs to support many different encodings; yet whenever data is passed between different encodings or platforms, that data always runs the risk of corruption.
U • bits for a character • Combination of
Audio Data • Samples are digital representations of the sound at a particular moment. • For example, audio CDs record sound using -byte samples sampled at a rate of times per second (the minimum number of times in order to maintain sound quality). • With so many samples per second, sound files take up a great deal of storage space. • EX: about MB for a 2-minute stereo song.
Graphics Data • Graphics data consists of still images, such as photographs or drawings. • One of the most common methods for storing graphics data is in the form of a • A grid of hundreds of thousands of dots (pixels), arranged to represent an image. • The color to be displayed at each pixel is represented by some combination of 0s and 1s, and the number of bits required to store the color for one pixel is called
Monochrome 1 bit Grayscale 8 bits
16 color image : 4 bit depth 256 color image : 8 bit depth True color image : 24 bit depth
How much storage space is required for ? • How much storage space is required for grayscale picture at resolution 800*600 ? • How much storage space is required for true color picture at resolution 800*600?
Video Data • Movie you see on TV, Video come from series of still pictures project continuously. • This will cause moving picture.
Video Data • Video data is displayed using a collection of frames; each frame contains a still graphical image. • When the frames are projected on after the other – typically at a rate frames per second – the illusion of movement is created. • With so many frames, the amount of data involved in showing a two-hour feature film can be substantial. Video Motion
How does the computer know if an error has occurred? • Bits travel from one point to another. The signal may be interfered by the environment that causes data error. • How can we detect this error?
Parity Bit • Parity bit, also called a check bit, is an extra bit added to a group of bits to make the parity of the group odd or even, for purposes of checking accuracy.
Data 0001 Sum of bits is odd or even Extra bit 0001 2 1 is Even 0001 1 is Odd 0
The sender and receiver must both • agree to use parity checking and • to agree on whether parity is to be odd or even. • If the two sides are not configured with the same parity scheme, communication will be impossible.
The System Unit • It houses • the motherboard (including the processor chip and memory chips) • Power supply • Storage devices
Power Supply • It is a device that converts AC to DC to run the computer.
Power Problem • Power surge • Power brownout • Power failure Picture http://www.gilliselectricinc.com/images/protection-surges.jpg
Surge Protector • It is a device that protects a computer from being damaged by surges (spikes) of high voltage. Williams ed8. p201 http://www.aeropause.com/archives/surgeprotector.JPG
Voltage Regulator • It is a device that protects a computer from being damaged by insufficient power. Williams 8ed. p202
UPS • A UPS (uninterruptible power supply) is a battery-operated device that provides a computer with electricity if there is a power failure. Williams 8ed. p202 http://www.hyper-v-mart.com/images/PowerWareUPS.jpg http://www.tdhvisions.com/images/UPS_6.jpg
Bay • It is a shelf or an opening used for the installation of electronic equipment, generally a hard drive, DVD drive.
The main circuit board in the system unit which contains • Soldered (nonremovable) components • Sockets or slots for components that can be removed – microprocessor chip, RAM chips, and various expansion cards. Williams 8ed. p202 http://asusmotherboards.org/wp-content/uploads/2009/02/asus-p5e3-motherboard-premium.jpg
Shape of Microprocessor • Microprocessor is a brain of your computer. • It performs processing.