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2 Information Processing. 2.1 Basic Knowledge of Computer Platforms. PROCESSING. OUTPUT. data. INPUT. info. 3 Processing Stages. Input Enter data into the computer Processing The computer works on the data Output The processed data or results are given out by the computer. *.
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2 Information Processing 2.1 Basic Knowledge of Computer Platforms
PROCESSING OUTPUT data INPUT info. 3 Processing Stages • Input • Enter data into the computer • Processing • The computer works on the data • Output • The processed data or results are given out by the computer *
5 Components of a Typical PC • Input devices • Output devices • Processing unit • Primary storage units / Main memory • Secondary storage units / Backing storage devices *
Input devices • Input devices are used for entering data (e.g. characters, numbers, sound, video, graphics and etc.) into the computer • E.g., mouse, keyboard, digitizer, microphone, bar-code reader, smart card (e.g. Octopus), scanner, Optical character recognition software, speech recognizer, Chinese handwriting recognizer, touching screen and etc. *
Output devices • Output devices are used for displaying processed data or information (e.g. graphics & movies on screen, printouts, sound and etc.) to the users • E.g., monitor (visual display unit), printer, speakers, plotter and etc. *
Processing unit • At the heart of every computer is the central processing unit (CPU), or processor, which executes program instructions and performs the computer's processing actions. • The CPU is a collection of electronic circuits made up of thousands of transistors placed onto an integrated circuit (also called a chip or microchip). • The two components of the CPU are the control unit (CU) and the arithmetic/logic unit (ALU) *
Primary storage units • it holds data only temporarily as the computer executes instructions. • 2 kinds of primary storage device: • RAM (Random Access Memory) • ROM (Read Only Memory) * RAM ROM
RAM • memory that permits data or information to be written into or read from any memory address at any time. • RAM stores data and information only as long as the computer is turned on (volatile). • ROM • offers random access to data, but it can hold data and information after the electric current to the computer has been turned off (non-volatile). • data can be read from memory but cannot be written into it *
Secondary storage unit • augments primary memory • is used to store data over the long term or for future use. • E.g., hard disks, floppy diskettes, magnetic tapes, CD-ROM (read-only), CD-R (recordable), CD-RW (rewrittable), DVD, magneto-optical (MO) disks, zip disks, jaz disks and etc. *
Why need secondary storage? • contents of primary memory remain there only temporarily. • data vanishes from primary memory as soon as the computer is turned off. • Primary memory is not large enough to contain the large volume of data and information associated with business application.
Input devices Processing unit Primary storage Output devices Secondary storage The relationship between 5 components *
4 step processing The processing sequence is a four step processing called the machine cycle. These four steps, all of which are directed by the control unit, are as follows: • fetch, or obtain the next instruction form memory; • decode, or translate the instruction into individual commands that the computer can process;
execute, or perform the actions called for in the instructions; and • store, or write the results of processing to memory. To execute the machine cycle, the control unit depends on registers, temporary storage areas in the processor.
Communication device • Modem • A modem modulates outgoing digital signals from a computer or other digital device to analog signals for a conventional copper twisted-pair telephone line and demodulates the incoming analog signal and converts it to a digital signal for the digital device. *
Analog and digital signal conversion • Digital-to-analog conversion is a process in which signals having a few (usually two) defined levels or states (digital) are converted into signals having a theoretically infinite number of states (analog). *
Modulation A modem modulates outgoing digital signals from a computer or other digital device to analog signals for a conventional copper twisted-pair telephone line. • Demodulation A modem demodulates the incoming analog signal and converts it to a digital signal for the digital device. *
Major Items Affect the Performance of Computer Operations • CPU • RAM • Cache • Video memory • Display adapter *
CPU • Clock speed is one measure of computer "power," but it is not always directly proportional to the performance level. • http://whatis.techtarget.com/definition/0,,sid9_gci211799,00.html From whatis.com
Bus • A bus is the path over which data are moved. • The width of the bus determines the amount of data that can be moved at one time.
Word • Word size is measured in bits. A word is the number of bits a computer can processsimultaneously. • The larger the word size, the faster a computer can process data.
Memory • The computer's workspace (physically, a collection of RAM chips). It is an important resource, since it determines the size and number of programs that can be run at the same time, as well as the amount of data that can be processed instantly. From whatis.com
Cache • L1 and L2 are levels of cache memory in a computer. • If the computer processor can find the data it needs for its next operation in cache memory, it will save time compared to having to get it from RAM. From whatis.com
L1 is "level-1" cache memory, usually built onto the microprocessor chip itself. For example, the Intel MMX microprocessor comes with 32 thousand bytes of L1. • L2 (that is, level-2) cache memory is built into the CPU chip or on a separate chip that can be accessed more quickly than the larger "main" memory. A popular L2 cache memory size is 1 MB. From whatis.com
Video RAM • Also called "VRAM," it is a type of memory used in a display adapter. It is designed with dual ports so that it can simultaneously refresh the screen while text and images are drawn in memory. It is faster than the common dynamic RAM (DRAM) used as main memory in the computer. From techweb.com
Display adapter • An expansion board that plugs into a desktop computer that converts the images created in the computer (digital) to the electronic signals (analog) required by the monitor. • The display adapter converts the characters or graphic patterns (bitmaps) within the computer's memory into signals used to refresh the display screen. From techweb.com
Display adapters also contain their own memory, which is used to build the images before they are displayed From techweb.com
6 Ways of Increasing Processing and Computer Speed • Cache memory • a form of high-speed memory that acts as a temporary holding/processing cell and eliminates the need to move data to and from the main memory repeatedly. • Co-processors • special chips designed to handle tasks that are performed often. By taking over this processing work from the main processor, they free the CPU to focus on general processing needs.
Accelerator boards • are add-in circuit boards that increase a computer's processing speed. • Packing more transistors on a chip • creating greater chip density, resulting in greater computing speed.
Reduced instruction set computing (RISC) • processes data more simply than complex instruction set computing. With RISC, data for the execution of an instruction are taken only from register. This both simplifies and accelerates instruction processing. • Withparallel processing • computing handle different parts of a problem by executing instructions simultaneously. In the end, the results of each parallel process are combined to produce a result.
Some Common Storage Devices • CD-ROM • CD-R • CD-RW • DVD • Zip • Jaz • Floppy diskettes • Hard disks * From techweb.com
CD-ROM • (Compact Disc Read Only Memory) A compact disc format used to hold text, graphics and hi-fi stereo sound. • It's like an audio CD with spiral, grooved tracks, but uses a different format for recording data. • The audio CD player cannot play CD-ROMs, but CD-ROM players can play audio discs. From techweb.com
CD-ROMs hold 650MB of data, which is equivalent to about 250,000 pages of text or 20,000 medium-resolution images. • The first CD-ROM drives transferred data at 150KB per second (1X). Speeds doubled to 300KBps (2X) and continued upward to more than 40 times (40X) the original. Access times range from 80 to 120ms. From techweb.com
The 120mm CD-ROM is the de facto standard for software distribution and for publishing large databases. • The smaller mini CD-ROM is only 80mm in diameter and holds 180MB (compared to the full-size 650MB). It fits into the deeper well in the center of the tray in most CD-ROM drives. • CD-ROMs have a silver cast just like audio CDs. From techweb.com
There is only one laser in a drive. Two are used here to illustrate the difference in reflection From techweb.com
How a CD-ROM is made ? From techweb.com
CD-R • (CD-Recordable) A recordable CD-ROM technology using a disc that can be written only once. • The drive that writes the CD-R disc is often called a "one-off machine" and can also be used as a regular CD-ROM reader. • CD-Rs create the equivalent of pits in the disc by altering the reflectivity of a dye layer. Different dyes can be used, including cyanine (green), pthalo-cyanine (yellow-gold) and metal-azo (blue). From techweb.com
Blank CD-R discs can be recorded once and read on any CD-ROM reader. CD-Rs have a gold, blue or green cast. From techweb.com
CD-R discs are used for beta versions and original masters of CD-ROM material as well as a means to distribute large amounts of data to a small number of recipients. • CD-Rs are also used for archiving data. A major advantage over other media is that they can be read in most CD-ROM drives. From techweb.com
"Burning" your own CD-Rs is very efficient for small distributions or when it is vital to create copies immediately. • However, when several hundred or more discs must be created, the CD-ROM manufacturing process is generally more efficient. • CD-ROMs are made on a pressing machine from a master plate that was derived from a CD-R recording. From techweb.com
greenish-gold or silver-blue cast, whereas CD-ROMs have a silver cast. (Image courtesy of Sony Electronics Inc.) • CD-R drives such as this internal drive from Sony look just like CD-ROM drives. Only the discs themselves look different. The underside of CD-R media typically has a From techweb.com
