Power Supply

  *A power supply may obtain energy from:

• Electrical energy transmission systems. 
• Common examples of this include power supplies that convert AC line voltage to DC voltage.
• Energy Storage devices such asbatteries andfuel cells.
• Electromechanical systems such as generators and alternators.
• Solar power. 

                               FSP250-60ATV-1A - 250 Watt ATX Power Supply

  =>C:\Documents and Settings\cyber41\Desktop\power supply.gif

  *Key Features:

1. Replaces Dell Dimension 8300 power supplies.
2. Common replacement power supply for HP, Compaq and Dell.
3. Integrated noise killer.
4. Internal ball bearing fan.

LT701

LT 322

                                                

System Unit --ROM

(1)

• The system unit includes the chassis, microprocessor, main memory, bus, and ports, but does not include the keyboard or monitor, or any peripheral devices.
• A system unit is sometimes called a box or main unit. 

How to Assemble a System unit.wmv :(2)







ROM(Read-Only Memory)

1. PROM (Programmable Read-Only Memory)
2. EPROM (Erasable Programmable Read-Only Memory)
3. EEPROM (Electrically Erasable Programmable Read-Only Memory)

   1. PROM (Programmable Read-Only Memory)

• The process is known as burning the PROM.
• This device uses high voltages to permanently destroy or create internal links (fuses or anti-fuses) within the chip.
• It is a permanent storage device that becomes a read-only memory after it is written once by the customer rather than by the chip manufacturer.
• They are frequently seen in video game consoles, or such products as electronic dictionaries, where PROMs for different languages can be substituted.

                      


   2. EPROM (Erasable Programmable Read-Only Memory)

• A type of computer memory chip that retains its data when its power supply is switched off & it is non-volatile.
• It can be erased only by exposing it to strong ultraviolet light & normally used in electronic circuits.
• EPROMs are easily recognizable by the transparent fused quartz window in the top of the package, through which the silicon chip can be seen, and which permits UV light during erasing.

                     

    3. EEPROM (Electrically Erasable Programmable Read-Only Memory)

• EEPROM-chip can be erased, either within a computer or externally, by electric power.
• There are two types of EEPROM: Electrically alterable read-only memory (EAROM) and Flash memory (or simply flash).
• It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products.

                       (3)

Citation:

-(1)http://www.webopedia.com/TERM/S/system_unit.html

-(2)http://www.youtube.com/watch?v=n6umAYBUYHE&feature=related

-(3)http://sunwayiconz.wordpress.com/

CHAPTER 6: THE SYSTEM UNIT

SYSYEM UNIT

• known as " sysyem chassis".
• container of electronic component that make up computer system.
• 4 basic types:

        ~Desktop contain the system's electronic components and selected secondary storage. Input and output devices are located outside of system unit.

http://www.techshout.com/hardware/2008/13/acer-aspire-3450-desktop-launched-in-the-indian-market/


        ~Notebook are much smaller and portable.It often called laptops.The monitor is attached by hinges.

http://hi.baidu.com/wangzhiyun85/blog/item/793fd6180628b80035fa4142.html


        ~Table PC are highly portable devices that support stylus tp input commands and data. (a)Accepts stylus input and has monitor swivels and folds onto its keyboard.

http://www.tabletpc2.com/Archives/2005%20Archives/News-Archive-December-2005.htm

                 (b)Has removable keyboard

http://techsupport24hours.com/tech-support-for-asus-eee-pc-t91/

   
        ~Handheld is the smallest and designed to fit into the palm of one hand.The most widely used handheld computers are personal digital assistants(PDAs) and smartphones.

BINARY CODING SCHEMES

• convert binary data into characters.
• 3 such schemes:

        ~ASCII-the most widely used for microcomputers.
        ~EBCDI-developed by IBM ,used primarly by large computers.
        ~Unicode -16bit code support both ASCII and EBCDI codes and internationallanguages.

SYSTEM BOARD

• known as motherboard.
• connects all system components and allows input and output devices to communicate with system unit.
• a flat circuit board covered with these electronic components including:

        ~Sockets provide connection points for chips.A chips is also called silicon chip,semiconductor,or integrated circuit.
        ~Slots provide connection points for specialized cards or circuit boards.
        ~Bus lines provide pathways that support communication.

http://computer.yourdictionary.com/slot-1

MICROPROCESSOR

• is a single chip that contains the central processing unit(CPU).
• 2 basic components:

        ~Control Unit tells the computer system hoe to carry out program instructions.
        ~Arithmetic-logic unit(ALU)performs logical and arithmetic operations.       

http://www.shutterstock.com/pic-8145061/stock-photo-close-up-of-microprocessor-chip-on-motherboard-in-computer.html

MEMORY

• is a holding data,instructions,and information.
• 3 types momory chips:

        ~RAM is called temporary or volatile storage because their contents are lost if power is disrupted.
   (a)Cache memory-a high speed holding area for frequently used data and information.
   (b)DIMM-to expand memory.
   (c)virtual memory-divides large programs into parts that are read into RAM as needed.

http://www.tomshardware.com/reviews/ram-scaling-notebook,1920-6.html


        ~ROM are nonvolite storage and control essential system operations.

        ~Flash Memory is a type of memory that does not ose it contents when power is removed.it is used to store information about a computer's configuration.



*** Information is getting from the book - Computing Essential 2011