Learning Objective: At this end of this Lesson the students can be able to: Define concisely what is computer. Identify the basic functions of computer. Discuss the evolution of computer. Discuss the different generation of computer. Classify and differentiate computer types.
Definition Is an electronic device that:5+2 5+2 5+2=7 5+2=7
Computer: Basic Function A device that: 1. accepts input input – whatever is put into the computer system. ex. words, symbols, numbers, pictures, audio signal, instructions from a computer program. needs an input device 2. process data data – refers to symbols that represent facts, objects, and ideas. process – a way in which a computer manipulates data this process is controlled by a computer program. processing takes place in a CPU (brain of computer)
Computer A device that: 3. stores data Types of Data Storage 1. Memory – (volatile) ex. memory card, CMOS 2. Storage Device –(non-volatile) ex. hard disk, floppy disk, usb flash disk, CD‟s etc., 3. Why is it important for a computer to have a data storage? 4. produces output output – is the results produced by a computer. ex. reports, documents, music, pictures, videos, etc., needs output devices
First Generation - 1940-1956: Vacuum Tubes first computers used vacuum tubes for circuitry, and were often enormous, taking up entire rooms Magnetic drums as primary storage device Uses machine languages for instr. Input punched cards and paper tape output printouts.
Examples of First Generation Computers UNIVAC – the first commercial computer delivered to a business client. First seen…. ENIAC – the first computer used for scientific studies. EDVAC – the first computer to hold both stored program as well as data
Second Generation - 1956-1963: Transistors Transistors replaced vacuum tubes smaller, faster, cheaper, more energy-efficient and more reliable. Computers could handle an enormous amount of data. used in business, universities, and government from companies.
Third Generation - 1964-1971: Integrated Circuits Drastically increased the speed and efficiency of computers. Uses keyboards and monitors and interfaced with an operating system. Computers been able to run different application program.
Fourth Generation - 1971-Present: Microprocessors Microprocessor or processor is an integrated circuit designed to process instructions. CPU is the most important element of a computer system
Assignment1. Search the internet for the name of the first UNIVAC, ENIAC and EDVAC created.2. Search for the first computer program developed for commercial use.3. Search for different brands of processor and compare the price of the processors with the same specification. (example 2.4 GHz)4. Search for significant contributions of the “Age of Connectivity” – 1991 to present. Ex: WI-FI
Capabilities and Scalability of Computer7/27/2012 17
Capabilities of Computer Capabilities of the computer is defined by its hardware and the software. Capability of computer is endless and limitless we cannot put boundary to its ability. Qualities that defines computer capability: 1. Speed 2. Repetitiveness 3. Accuracy 4. Logic operation 5. Store and recall operation 6. Self checking 7. Self operation7/27/2012 18
Scalability of Computer Scalability is the ability of the system to improve its performance with the additional hardware, proportional to the additional load. Dimension of Scalability: Load scalability: The ability of a machine to adjust its operation to accommodate changing load. Geographic scalability: The ability to maintain performance when there geographic growth. Functional scalability: The ability to enhance the system by adding new functionality at minimal effort.7/27/2012 19
General Applications of Computer Scientific Research Ex. Cloning, weather forecasting, etc.. Business / Commerce Ex. Banking, online shopping, etc.. Entertainment Ex. Movie effects, gaming, etc.. Education / Information Gateway Ex. World wide web, e-learning, etc.. Connectivity/Communication Ex. Email, web conferencing, blue tooth etc.. Aviation Air Traffic Control, Satellite, etc.. Military Operations Ex. Nuclear weapon, GPS (Global Positioning System), etc.. Programming VBasic, Java, Perl, C++, Delphi, etc.. Artificial Intelligence Robotics, Speech Recognition, etc..7/27/2012 20
Classification of Computer How do we classify computer? 1. Technology 2. Function 3. Physical Size 4. Performance 5. Cost Computer Categories 1. Mainframe 2. Minicomputer 3. Microcomputer 4. Supercomputer 5. Server
Mainframe Large, fast and expensive Centralized storage, processing, distribution, and management of large amount of data. Reliable and secured. used by businesses and government. Mainframe usually comes in 3 units overall operations handles communication with all users. finding data requested.
IBM System/360 (S/360) speed from 0.034 MIPS to 1.700 MIPS designed to cover the full range of applications, from small to large, both commercial and scientific. The design is considered by many to be one of the most successful computers in history.
Minicomputer minicomputer is a system capable of supporting from 4 to about 200 users simultaneously smaller, less expensive, and less powerful machines Perform -> all terminals; business applications Still existing?
The PDP-8 (1960’s) the first successful commercial minicomputer built with discrete transistors Built 60‟s – distribute ‟65 Digital Equipment Corporation (DEC)
Microcomputers general-purpose computer useful for individuals, and which is intended to be operated directly by an end user Also called personal computers, PC ex. desktop, notebook, laptops, PDA
ALTAIR 8800 microcomputer design from 1975, based on the Intel 8080 CPU sold thousands in the first month. recognized as the spark that led to the personal computer revolution: computer bus designed.
Apple II 1977 - one of the first highly successful mass produced microcomputer among the first home computers on the market, and became one of the most recognizable and successful. Sold between 5 and 6 million until 1993
Supercomputers Fastest and most expensive (1M – 100M) “Compute-intensive” tasks Molecular modelling Code breaking Weather prediction physical simulations Speed -> Complex processing Movement of thousands of particles in a tornado Creating realistic animation
Illiac IV one of the most infamous supercomputers ever built. 256 processors – parallel processing
The Cray 1 In 1975 the 80 MHz Cray-1 was announced. designed by a team including Seymour Cray for Cray Research. design to use integrated circuits (ICs)
IBM Roadrunner worlds fastest computer US$133-million U.S (DoE) National Nuclear Security Administration. development since 2002, and went online in 2006. Feb 2009 – starts development of “Sequia” – 20 petaflops
Server A special type of computer that is configure to “serve” the computers on a network. store and distribute data and/or allow clients to exchange files or access a centralized resources. can be personal computer, a mainframe or a supercomputer.
Learning Objective: At the end of this lesson, the student should be able to: Identify the different components of the computer system. Discuss the role and importance of each component in the computer system. Differentiate input devices from output devices. Enumerate common input and output devices. Define software and discuss its importance in the system. Enumerate the different types of software and their functions.
Learning Objective At the end of this lesson, the students should be able to: Identify the components of the System Unit Enumerate the components of the motherboard Explain the function of the processor: the Control Unit, Arithmetic and Logic unit. List and briefly explain the various types of memory. Explain the function of buses and list different types of buses. Explain the various types of ports and connectors. Discuss the functions of expansion slots and adapter cards. Differentiate internal and external bays. Explain the function of power supply. Define ‘bit’ and describe how a series of bits are used to represent data.ext: Definition of System Unit
The System Unit the main body of a computer. Consist of: motherboard cooling fans, internal disk drives memory modules expansion cards power supplyext: System Unit w/ labeled parts
Rear View of the system unitext: System Unit for portable
System Unit for Laptops and PDA keyboard and pointing device are on top of the system display is part of the unitext: Motherboard
The Motherboard Also known as the system board. main circuit board of the system unit. Components attached to the motherboard processor memory buses system clock expansion slots and adapter cards portsext: Function of motherboard
Function of the Motherboard provides means of communication between processor and memory. controls the flow of information through all the components. bus is a subsystem that transfers data between computer components inside a computer or between computers. PCI Express bus card slots (from top to bottom: x4, x16, x1 and x16), compared to a traditional 32-bit PCI bus card slot (bottom).ext: Function in figure
bus provides means of transportation bus stops are the memory, the processor and other peripheral devices bus carries data and instruction from one stop to another and drop them off as these stopsext: Old Motherboard
Old Motherboard Specifications An old IBM 8088 Processor Intel 8088 motherboard Speed 4.77 MHz RAM 16K-640K ROM Unknown Cassette Tape, optionally 5.25" Storage floppy drives, hard disks Expansion 5 expansion slots Industry Standard Bus Architecture (ISA) Initially CGA (320x200x16 color, 640x200x2 Video color) or monochrome (80x25 text only)) I/O Parallel, Serialext: Modern Mboard
Modern motherboards include, at a minimum: sockets (or slots) in which one or more microprocessors are installed memory slots into which the systems main memory is installed a chipset which forms an interface between the CPUs front-side bus, main memory, and peripheral buses non-volatile memory chips containing the systems firmware or BIOS a clock generator which produces the system clock signal to synchronize the various components slots for expansion cards power connectors flickers, which distribute electric power to the CPU, chipset, main memory, and expansion cards.[ext: Figure
The Processor central processing unit (CPU) brain of the computer most important and most expensive various sizes and speed Two basic Components 1. Control Unit 2. Arithmetic and Logic Unit (ALU) Functions of the processor 1. execute instructions instructions from program 2. process dataext: Device communication
How device communicates with processor to complete a task Processor instruction data information data information instruction data input devices information output devicesext: Control unit Storage device
The Control Unit components of the processor that manages all of the computer resources. control and directs the flow of data through the processor and to and from other devices. interprets the instructions for a program and executes necessary actions to carry out the instruction.ext: ALU
The Arithmetic And Logic Unit performs arithmetic related operations, comparison operations and logical operations. Functions of Arithmetic Logic Unit (ALU) Arithmetic addition, subtraction, multiplication, division Comparison equal to, greater than, less than, greater or equal to, lesser or equal to Logical AND, OR, NOText: Machine cycle
The Machine Cycle The repetition of series of steps for every instruction the processor executes. Machine Cycle Instruction Cycle Execution Cycle Fetching Decoding Executing Storing Retrieves Translates Carries out Writes (stores) (fetches) a (decodes) (execute) the results to command/data instructions into commands listed memory. from the memory signals the in the instructions computer can understandext: performance
Performance Factors of Processor A. Registers small, high-speed temporary storage located in the ALU. The amount of data which the computer can work with at any given time is referred to as the word size. word size is measured in bit a 64-bit processor can process data twice as much as 32- bit. Functions of Registers store the locations where instructions were fetched from. store an instruction while the instruction is being decoded by the control unit. store data while the ALU computes the data. store the results of calculationsext: System clock
Performance Factors of Processor B. System Clock timer that times the processing operations of the computer. sets the pace for executing instructions. Clock cycle Measured in hertz, cycles per second. 2.4 GHz means ~ 2.4 billion cycles per second. processor can be able to execute instruction in every cycle. the speed of processor to carry out an instructions depends on the speed of the system clock.ext: Cache Memory
Performance Factors of Processor C. Cache Memory (“cash”) sometimes called “RAM cache” or “cache memory” – measured in KB or MB Special high-speed memory that allows a microprocessor to access data rapidly than from memory located elsewhere on the motherboard. Level1 cache(L1) – built into the processor chip. Level2 cache(L2) – located on a separate chip and takes little more time to get data to the processor. used in motherboard, but was later built into the CPU Usually tied with the processor brand and model – non-upgradeable.ext: Method of processing
Performance Factors of Processor D. Method of processing Processors are basically designed to process one instruction at a time, this refers to as Serial Processing. process must complete all of the steps of machine cycle before it begins to process a new instruction. Pipelining a technology that allows a processor to begin a new instruction before it completes the previous one. Parallel Processing new technology for new generation processors allows simultaneous multi-processing. pizza analogyext: Fast processor
Memory Memory is an electronic components in your computer that stores: instructions waiting to be executed data needed by the instructions and the results of processed data. How does computer finds requested data?
A1 B1 C1 D1 A2 B2 C2 D2 01101100 10001011 A3 B3 C3 01100111 10001100 D3 #9 Wilson St Memory are virtual location inside your the content of each computer memory address is each location has called bytes unique identification called addressext: Memory Arcihtecture
common memory architecture within most modern computers.ext: Units of memory
Memory And Storage Size Term Abbreviation Approximate Exact Amount Approximat Size e Pages of Text Kilobyte KB or K 1 thousand 1,024 bytes ½ bytes Megabyt MB 1 million bytes 1,048,576 bytes 500 e Gigabyte GB 1 billion bytes 1,073,741,824 500,000 bytes Terabyte TB 1 trillion bytes 1,099,511,627,776 500,000,000 bytes stated in terms of the number of bytes available for storage in the chip or deviceext: Types
Types of Memory Volatile Non-volatile Temporary memory Permanent memory Contents are lost when the Contents can be preserve computer is turned off. even if the computer is off. Common Type Common Types RAM ROM Random Access Memory Read-only memory Flash memory CMOSext: RAM
RAM Main memory or primary storage RAM is considered "random access" because you can access any memory cell directly holds operating system files, program files and data files needed for processing. can handle multiple programs simultaneously. Ram is volatile. The process of copying items from RAM to a storage device is known as saving. What are the different types of ram and which one is on your pc?
Types of Ram Chips DRAM – Dynamic RAM SRAM – Static RAM Needs to refresh thousands Doesn‟t need to refresh of times to keep contents Slower Faster Less Expensive than SRAM Used for large amount of More expensive temporary storage. Used to create the CPU‟s cache memory.ext: DRAM
How Dynamic RAM Works DRAM mainly consists of millions capacitors and transistors Transistor acts as a switch that control the flow of electrons to the capacitors. To store 1, the bucket is filled, to store 0 the bucket is emptied. 0 and 1 represent bit, the smaller unit of information in a computer. The problem with the capacitors bucket is that it has a leak. In a matter of a few milliseconds a full bucket becomes empty. Therefore, for dynamic memory to work, either the CPU or the memory controller has to come along and recharge all of the capacitors holding a 1 before they discharge.
How Static RAM works Static RAM uses flip-flop technology that holds each bit of memory permanently while there is electric current. Using flip-flop for a memory cell doesn‟t require refreshing but requires a lot of wiring This makes static RAM significantly faster than dynamic RAM but takes up a lot more space on a chip than a dynamic memory cell. Therefore, you get less memory per chip, and that makes static RAM a lot more expensive. used to create the CPUs speed-sensitive cache, while dynamic RAM forms the larger system RAM spaceext: Types of RAM
Common Types of RAM SRAM: DDR SDRAM: Does not need refreshing, but Double data rate synchronous requires several wiring connected to dynamic RAM is just like SDRAM the transistors, used primarily for except that is has higher bandwidth, cache. meaning greater speed. DRAM: RDRAM: Rambus dynamic type of memory that requires constant random access memory refreshing. use of a special high-speed data bus SDRAM: called the Rambus channel that makes memory chips work in parallel Synchronous dynamic random access to achieve a data rate of 600 MHz, or memory 1,600 MBps. faster than DRAM because they are Speed versus heat synchronous with the system clock. the most common form in desktops today.ext: Memory module
Memory Modules SIMM, which stands for single in-line memory module. 30-pin connector, 3.5 x .75 inches in size – max 32 MB In most computers, you had to install SIMMs in pairs of equal capacity and speed. This is because the width of the bus is more than a single SIMM. Later 4.25 x 1 – max 256 MBext: DIMM and RIMM
Memory Modules DIMM, which stands for dual in-line memory module. 168-pin or 184-pin connector, 5.4 x 1 inch in size 8 MB to 1 GB RIMM, which stands for Rambus in- line memory module comparable in size and pin configuration to DIMM but uses a special memory bus to greatly increase speed 800 MHz, or 1,600 MBps data rate Can we use it for portable pc?ext: SODIMM
Memory Modules SODIMM, which stands for small outline dual in-line memory module 144 or 200 pins, 2 x 1 inch 16 MB to 1 GB per module. used in notebooks and laptops. some notebook uses smaller DIMMs, known as MicroDIMM.ext: Most common memory type
Other Memory Modules Top L-R, DDR2 with heat-spreader, DDR2 without heat-spreader, Laptop DDR2, DDR, Laptop DDRext: Access Time
Access Time The amount of time it takes for the processor to read data, instructions, and information from memory. usually expressed in ns (nanoseconds). Newer memory have speed expressed in MHz. RAM TYPE RAM Speed EDO 16 MHz (60 ns) SDRAM 66 MHz (15ns) – 133 MHz (7.5ns) RDRAM 600 MHz (1.7 ns) – 800 MHz (1.3 ns)ext: How much do we need?
How much RAM do you need? The amount of RAM for your system varies depending on several factors. 1. The Operating System you‟re putting in to your computer. Windows 95/98, min of 32 MB, 64 MB is recommended. Windows NT/2000 min 64 MB, 128 MB is recommended. Windows XP, min 128MB, 256MB is recommended. Windows Vista, min 256, 512 is recommended 2. How you‟re going to use your pc. High-end user vs. basic user. Does adding more RAM makes your computer faster?ext: Other Primary Storage
ROM Read-only memory also known as firmware, is an integrated circuit programmed with specific data when it is manufactured. ROM chips are used not only in computers, but in most other electronic items as well.ext: Characteristics of ROM
Characteristics of ROM Data stored in these chips is nonvolatile -- it is not lost when power is removed. Data stored in these chips is either unchangeable or requires a special operation to change, unlike RAM. Ideal memory for storing the BIOS Basic Input Output Systemext: Types of ROM
Types of ROM ROM ROM uses a diode to its control circuit. ROM chip works necessitates the programming of perfect and complete data when the chip is created. ROM are disposable. They use very little power, are extremely reliable and, in the case of most small electronic devices, contain all the necessary programming to control the device.ext: PROM
Types of ROM PROM programmable read-only memory Blank chips that can be coded by anyone with a special tool called a programmer. Mainly consists of wires and fuses that needs to be burn to embed program. This process is known as burning the PROM. PROMs can only be programmed once. Blank PROMs are inexpensive and are great for prototyping the data for a ROM before committing to the costly ROM fabrication process.ext: EPROM
Types of ROM EPROM Erasable programmable read-only memory Can be rewritable many times but needs to be erased. Erasing an EPROM requires a special tool that emits a certain frequency of ultraviolet (UV) light Erasing requires removing into the device and exposure under UV light for several minutes.ext: EEPROM
Types of ROM EEPROM Electrically erasable programmable read-only memory. The chip does not have to removed to be rewritten. The entire chip does not have to be completely erased to change a specific portion of it. Changing the contents does not require additional dedicated equipment. Instead of using UV light, you can return the electrons in the cells of an EEPROM to normal with the localized application of an electric field to each cell. The process of rewriting is versatile but slow.ext: FLASH
Types of ROM Flash memory type of EEPROM that uses in-circuit wiring to erase by applying an electrical field to the entire chip or to predetermined sections of the chip called blocks. Flash memory works much faster than traditional EEPROMs because it writes data in chunks, usually 512 bytes in size, instead of 1 byte at a time.ext: FLASH
FLASH A portable storage devices that use a type of electronic memory called flash memory. also known as a solid state storage device, meaning there are no moving parts instead purely electronic. Here are a few examples of flash memory: Your computers BIOS chip CompactFlash (most often found in digital cameras) SmartMedia (most often found in digital cameras) Memory Stick (most often found in digital cameras) PCMCIA Type I and Type II memory cards (used as solid-state disks in laptops) Memory cards for video game consolesext: Flash vs HDisk
Advantages of using flash memory over hard disk There are a few reasons to use flash memory instead of a hard disk: It has no moving parts, so its noiseless. It allows faster access. Its smaller in size and lighter. Why can‟t we just use flash memory for everything?ext: CMOS
CMOS Complementary Metal Oxide Semiconductor." Technology used in some ROM chips, flash memory chips and other types of memory. run efficiently and fast but using up very little power. You may also find CMOS memory in your computer, which holds the date and time and other basic system settings. The low power consumption of CMOS allows the memory to be powered by a simple Lithium battery for many years.
Computer Bus a subsystem that transfers data between computer components inside a computer or between computers. allows the travel of bits from one destination to another bit is the smallest unit of data that computer can process and store. bit is represented by 0 and 1 0 and 1 are typically referred to as the machine language. 8 bits = 1 byteext: Buses Diagram
Computer buses •FSB or frontside busThe backside bus is a is a physicaleparate connection connection thatetween the processor actually connects thend the Level 2 cache. processor to most ofThis bus operates at the other faster, usually at the components.ame speed as the • usually operates atrocessor, so all that 400-MHz, with neweraching works as systems running at •PCI bus ficiently as possible. 800-MHz. • These slower buses connect to the system bus through a bridge, which is a part of the computers chipset and acts as a traffic cop, integrating the data from the other buses to the systemext: Types bus.
Types of Buses Internal Buses External Buses also known as the system bus also known as expansion or the local bus. reside on the motherboard and bus. connects the processor to connect external devices other devices on the main circuit board. into the main circuit Data bus – used to send and board. receive data between devices Address bus – connects used by keyboard, mouse, processor and ram, responsible monitor and printer for addressing of requests.ext: Factors
Factors That Affects the Speed of data transfer Bus Width The number of bits that the computer can transmit at one time. 32-bit bus can transmits 32 bits (4 bytes) 64-bit bus can transmits 64 bits (8 bytes) Bus Speed The speed that the bus could transfer data from one device to another. Measured in MegaHertz (MHz) current bus speed is 400 MHz – 800 Mhz newerext: Standard Bus
Standards for Different Buses 1. ISA – Industry Standard Architectural Bus 2. VESA/VL Bus – Video Electronics Standard Association Local Bus 3. PCI – Peripheral Component Interconnect Bus 4. AGP – Accelerated Graphic Port Bus 5. PCI Express– Peripheral Component Interconnect Express Bus 6. USB – Universal Serial Bus 7. IEEE 1394 – Firewire 8. PC Card 9. Express Card
ISA computer bus standard for IBM compatible computers. still used to connect slower devices, such as modems and input devices to the processor. Later on replaced by 32-bit EISA Five 16-bit and one 8-bit ISA slots on a motherboard
VESA Video Electronic Standard Association Local Bus A VLB slot itself was an extension of an existing ISA slot. Indeed, either a VLB or an ISA card could be plugged into a VLB slot. Bus width 32 bits Compatible with 8 bit ISA, 16 bit ISA, VLB
PCI Peripheral Component Interconnect The PCI Local Bus developed by Intel is common in modern PCs, where it has displaced ISA and VESA Local Bus as the standard expansion bus, and it also appears in many other computer types Offer past transfer speeds and a 32-bit or 64-bit data bus. Typically house a graphics card, sound card, video card, video capture card, modem, or network interface card.
AGP Accelerated Graphics Port a high-speed point-to-point channel for attaching a video card, primarily to assist in the acceleration of 3D computer graphics. The primary advantage of AGP over PCI is that it provides a dedicated pathway between the slot and the processor rather than sharing the PCI bus. Number of devices: 1 device/slot Capacity up to 2133 MB/s
Specs for each generation per lane PCI Express a computer expansion card standard designed to replace the older PCI and AGP standards. Introduced by Intel in 2004, PCIe is the latest standard for expansion cards that is available on mainstream personal computers.Specs for each generation per lane Clock Transfer Data rate speed rate1.x 1.25 GHz 2.5 GT/s 250 MB/s A PCI Express x16 slot2.0 2.5 GHz 5 GT/s 500 MB/s3.0 4 GHz 8 GT/s 1 GB/s A PCI Express x1 slot
USB Universal Serial Bus (USB) USB was designed to allow many peripherals to be connected using a single standardized interface socket and to improve plug and play capabilities by allowing hot swapping hot swapping allows devices to be connected and disconnected without rebooting the computer or turning off the device. USB can connect computer peripherals such as mice, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, personal media players, flash drives, and external hard drives. For many of those devices, USB has become the standard connection method. Supports up to 127 devices connected in a daisy chain
IEEE 1394 - FIREWIRE The IEEE 1394 interface is a serial bus interface standard for high- speed communications and real-time data transfer, frequently used by personal computers, as well as in digital audio, digital video, automotive, and aeronautics applications. It remains the primary transfer mechanism for almost all high end professional audio and video equipment. Used by Mac but now available to IBM-compatible pc.
PC Card PC Card (originally PCMCIA Card) PCMCIA - Personal Computer Memory Card International Association form factor of a peripheral interface designed for laptop computers. PC Card was originally designed for computer storage expansion, but later on become the form for attaching network cards, modems, and hard disks. Allows attach/detach without affecting the computer.
Express Card ExpressCard is a hardware standard expansion slot, commonly found in laptop computers, replacing older and bigger PC Card slots. Uses of E-Card audio/video adapters, storage modules storage adapters wireless adapters TV tuners various memory card readers. Some popular ExpressCard® applications include TV Tuners, eSATA, FireWire, wireless WAN and wireless networking.
Expansion Port Expansion Port Any connector that passes data in and out of a computer or peripheral device. could be housed on an expansion card. could be built into the system unit. How to figure out which connector for which port?ext: Port Diagram
Universal Serial Bus (USB) A serial bus standard to connect devices to a host computer. sends data over single data line. 1.0 – speed from 1.5Mbit/s to 120Mbit/s 2.0 – speed 480 Mbit/s SB is a standard port designed to improve plug and play capabilities by allowing hot swapping. hot swapping allows devices to be connected and disconnected without rebooting the computer or turning off the device.ext: Firewire
IEEE 1394 interface (FireWire) A serial bus interface standard for high-speed communications and real-time data transfer. Since 2003 many computers intended for home or professional audio/video use have built-in FireWire.ext: Ethernet
Ethernet Port Ethernet is a family of frame-based computer networking technologies for local area networks (LANs). It defines a number of wiring and signaling standards for the Physical Layer of the OSI networking model.ext: Serial
Serial Port A serial communication physical interface through which information transfers in or out one bit at a time (contrast parallel port). Sends data over a single data line one bit at a time at speeds of 56 kbps. Use to connect earlier mouse or modem.ext: Parallel
Parallel Port A parallel port is a type of interface for connecting various peripherals. It is also known as a printer port. Sends data simultaneously over 8 data lines at speeds o 12,000 Mbit/s. Printer, external CD-ROM drive, Zip drive, external hard disk.ext: PS/2
PS/2 Connector The PS/2 connector is used for connecting some keyboards and mice to a PC compatible computer system. Its name comes from the IBM Personal System/2 series of personal computers, Replaced the older "serial mouse" and keyboard connector (but not interchangeable) Serial data at 10 to 16 kHzext: VGA
VGA Port Video Graphics Array (VGA) refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987 also known as RGB connector, D-sub 15, mini sub D15 and mini D15 Used to connect an analog monitor to the system unit.ext: DVI
DVI Port The Digital Visual Interface (DVI) is a video interface standard designed to provide very high visual quality on digital display devices such as flat panel LCD computer displays and digital projectors. It is partially compatible with the High-Definition Multimedia Interface (HDMI) standard in digital mode (DVI-D), and VGA in analog mode (DVI-A).ext: SCSI
SCSI - (pronounced scuzzy), Small Computer System Interface A set of standards for physically connecting and transferring data between computers and peripheral devices. sends data simultaneously over 8 or 16 lines at speeds between 40Mbit/s and 640Mbit/s. Supports up to 16 devices. SCSI is most commonly used for hard disks and tape drives, but it can connect a wide range of other devices, including scanners and CD drives.
Computer Drive Bays Refers to a location in a system unit where a hard or floppy disk drive, CD-ROM drive or tape drive can be installed. A drive bay is a standard-sized area for adding hardware to a computer. Thus, the number of drive bays in a computer determines how many mass storage devices can be internally installed. Commonly used to store disk drives, although they can also be used for front-end USB ports, I/O bays, card readers, fans, tool storage, and other uses.ext: Type: Internal
Internal Bay Also referred to as hidden bays There is no physical outside access. Cannot be used for removable media, such as floppy drives, and USB.ext: Type External
External Bay Also referred to as exposed bay There is a need for physical outside access. Floppy, drives and CD- ROMs slide into external bays and can be seen (and accessed) from the front of your system case.ext: Pow Supp
Power supply unit (computer) A power supply unit (PSU) is the component that supplies power to the other components in a computer. Designed to convert (AC) electric power to usable low- voltage DC power for the internal components of the computer. Some have power selector while some have auto power detection.ext: Connector
Typical Connectors for the PS PC Main power connector is the connector that goes to the motherboard to provide it with power. The connector has 20 or 24 pins. 4-pin Peripheral power connectors (usually called Molex for its manufacturer) that goes to the various disk drives of the computer. 4-pin Berg power connectors (usually called Mini-connector or "mini-Molex"): This is one of the smallest connectors that supplies the floppy drive with power. Auxiliary power connectors: There are several types of auxiliary connectors designed to provide additional power if it is needed.ext: Digital Rep
Learning Objective After this lesson, the students should be able to: Define and differentiate computer program and computer software. Enumerate different type of software. Differentiate System Software and Application Software Define and enumerate the different types of System Software Define and enumerate the different types of Application Software
DEFINITION COMPUTER PROGRAM Is a set of detailed, step-by-step instructions that tells a computer how to solve a problem or carry out a task. COMPUTER SOFTWARE The instructions and associated data, stored in electronic format, that direct the computer to accomplish the task. Differentiate Software, Program and Application.
CLASSIFICATION of SOFTWARE Software are classified based on how they could be used. 1. Copyrighted Software 2. Licensed Software 3. Shareware 4. Freeware
Copyrighted Software software that is exclusive to the owner or the developer. copyright - form of legal protection that grants the copyright exclusive rights to copy the software, to distribute or sell it, and modify it. I purchased a software, can I copy it for my friends? Exclusive Rights in Copyrighted Works 1. Only the copyright owner can reproduce, sell, or distribute the copyrighted software. 2. It is legal to copy the software from the distribution disks to the hard disk of your computer. 3. It is legal to make an extra copy of the software in case the copy you are using becomes damaged 4. If you give away or sell the software, you cannot legally keep a copy. 5. You cannot legally sell or give away modified or copies of the software without permission.
Licensed Softwaresoftware that is protected by law stating the constraints and limitation of the use. software license - legal contract that defines the ways in which you may use a computer program. Differentiate copyright and license? license can extend the regulations declared by the copyright. shrink wrap license – a license that is usually attached in the plastic wrapper of a disk, CD or DVD software
Licenses for Users Single-user license limits the use of the software to only one user at a time Multiple-user license - allows more than one person to use a particular software package Concurrent-use license - allows a certain number of copies of the software to be used at the same time Site license - generally allows the software to be used on any and all computers at a specific location. What about those software offered over the internet for free?
Shareware is a copyrighted software marketed under a “try before you buy” policy.
Freeware also refers to as public domain software put in the public domain to be used by any person without limitations
SOFTWARECATEGORIES System SoftwareApplication Software
System Software helps the computer carry out its basic operating tasks. Classification of System Software 1. Operating systems 2. Utility programs 3. Device Driver 4. Computer Programming Language 5. Communication software.
Operating System Is essentially the master controller for all of the activities that takes place within a computer. It sets the standards for all the program and application that will be used in a computer
Utility ProgramsDesigned to augment the operating system by providing a way for a computer user to control the allocation and use of hardware resources. ex.(OS utility) Defragmenter, Diskformatting, DiskPartitioner, Scandisk etc… ex.(Optional Utility) Norton PartitionMagic, McAfee Antivirus, Symantec File Recovery etc..
Device Driver The system software that helps the computer control a peripheral device.
Computer Programming Language Allows a programmer to write a program using English-like instructions.
Communication Software Allows multiple computer to communicate and share resources Internet LAN WAN
Application Software helps the human user perform an specific task. can be generic or be-spoke Classification of Application Software 1. Document Production 2. Graphic Software 3. Presentation 4. Spreadsheet and Statistical 5. Database 6. Information and Reference 7. Connectivity / Communication 8. Education and Training 9. Multimedia 10.Gaming and Simulation
Document Production Software group of software specific for writing software documentation, designing a brochure, laying out school newsletter etc WORD PROCESSING SOFTWARE replaced typewriters for producing documents such as report, letter, papers and manuscript. ex. MSWORD, Corel WORPERFECT, Lotus WORDPRO DESKTOP PUBLISHING SOFTWARE takes word processing software one step further by helping you use graphic design technique to enhance the format and appearance of a document. ex. AdobePageMaker, Corel Ventura Microsoft Publisher WEB AUTHORING SOFTWARE helps you design and develop customized Web pages that you can publish electronically on the internet. ex. SoftSquad HotMetal, Macromedia Dreamweaver, MSFrontpage
Graphic Software group of software specific that helps you create, edit, and manipulate images. PAINT SOFTWARE sometimes called image editing software, used to draw or create paintings, sketches and other images ex. MSPAINT, CORELDRAW etc PHOTO EDITING SOFTWARE includes feature specially designed to fix poor quality photos. ex. PHOTOSHOP, Windows Imaging 3-D GRAPHICS SOFTWARE helps you create and render three dimensional object. ex. MAYA, 3D Studio, AutoCAD
Presentation Software group of software that provides all of the tools you need for combining text, graphics, animations and sounds into a series of electronic slides. ex. Microsoft Powerpoint, Lotus Freelance Graphics
Spreadsheet and StatisticalSoftware SPREADSHEET SOFTWARE perform calculations based on numbers and formulas that you enter. ex. MsExcel, Lotus 123 STATISTICAL SOFTWARE helps you analyze large sets of data to discover relationship and patters. ex. SPSS, JMP, and DATA DESK Mathematical Modelling Software provides tools for solving a wide range of math, science, and engineering problems ex. MathCAD and MATHEMATICA
Database Software provides a flexible way to join and summarize the information in more than one file.
Information Reference Software software that provides a collection of information and a way to access that information. ex. Microsoft‟s Encarta, Britannica, Comptons Encyclopedia
Connectivity / CommunicationSoftware software that connects your computer to a local computer network on the internet and provides tools that you can use to take advantage of the information and communications they offer. ex. Yahoo messenger, Eudora Email, Netscape and IE
Education and Training Software software that helps the user practice new skills.
Multimedia Software software that transform your computer into video and audio station.
Games / Simulation Software computer into a game station for entertainment and learning purpose.
Activity 3 Assemble your virtual ideal personal computer by browsing different parts comprises of: 1. Display Device 2. System Unit 3. 5 Input Devices (state your personal purpose) 4. 5 Output Devices (state your personal purpose) 5. If you would be installing 10 Software in your assembled computer, what are those? (state your purpose) 6. Create the presentation about your pc. 7. Name the presentation file: Fullname_Act2
Data Representation A way of converting letters, sounds, and images into electrical signals. Why there is a need for conversion? Aext: Why Digital
Why Are Computers Digital Digital device works with discrete – distinct or separate data or digits such as 1 and 0. Analog device works with continuous data. Digital Technology are relatively simple, dependable and adaptable technology. switches have only two states On or Off. 0011 – “off” “off” “on” “on” 0‟s and 1‟ are called the binary digits – “bits”ext: Num & Data
Representing Numbers and Letters Numeric data consists of numbers that might be used in arithmetic ie., annual income, score in exams, age. Computers represent numeric data using the binary number system, also called “base 2”. Character data is composed of letters, symbols, and numerals that will not be used in arithmetic operations. ie., name, address, gender, statusext: Rep vid & Snd
Representing Sounds and Video Computers must digitize colors, notes and instrument sounds into 1‟s and 0‟s. Digitizing is the process of converting colors and sounds into numbers which can be represented by bits. How does computer identify which digits are for which file? file header file identification stored along with the file and can be read by the computer, but never appears in the screen.ext: Diff b & B
Quantifying Bits and Bytes Difference between bits and bytes bit is the smallest unit of data Byte is equivalent to 8 bits bit is abbreviated by lowercase b while byte is represented by uppercase B bit is used for transmission speed Byte is used to denote disk capacity.
Lesson Objective: At the end of this lesson, the students should be able to: Discuss the importance of storage device in the Computer System Differentiate memory and storage. Differentiate Logical and Physical storage. Differentiate the two technologies in storage such as; Magnetic Storage and Optical Storage. Enumerate different types of magnetic storage devices and discuss their operation, characteristics, and advantages and disadvantages. Enumerate different types of optical storage devices and discuss their operation, characteristics, and advantages and disadvantages. List and describe other special purpose storage devices. Explain enterprise Storage Systems and Data Warehouses.ext: Storage Perception
Two Storage Perceptions 1. Logical Storage How we think data are stored in our storage device. ie. Data inside the folder or on the physical devices. 2. Physical Storage Its how data are actually stored in our storage devices. It‟s the process being done by the computer and the storage devices.ext: Diff memory & SD
Memory vs Storage Devices Memory (volatile) Sometimes called primary storage A temporary holding place for data and instructions. More expensive yet faster than other storage devices. Storage Devices (non-volatile) Sometimes called secondary storage. An area in the computer where data are permanently stored. Cheaper than memory chips, has higher storage capacity yet slower data access.
Components Of Data Storage Storage Media The physical mediums on which data, information and instructions are held. Also known as secondary storage. Kinds of Medium 1. Floppy Disk 2. Hard Disk 3. Mini Disk 4. CD 5. PC card/Memory card 6. Other storage such smart cards, microfilm, tapes and other special purpose storage device.ext: Components of DS
Components Of Data Storage Storage Device Piece of hardware that saves (writes) or retrieves (read) data, information and instructions from storage media. Kinds of Devices 1. Floppy Disk Drive 2. Hard Disk Drive 3. Tape Drives 4. CD Drivesext: Storage Basics
Storage Basics Writing Is the process of transferring data, information, and instructions from main memory to the storage medium. Reading Is the process of transferring data, information, and instructions from medium to the storage main memory. Storage capacity The amount of bytes of data, information and instructions that can be kept by storage medium.ext: Storage Tech
Storage Technology1. Magnetic Storage2. Optical Storage
Magnetic Storage Stores data by magnetizing microscopic particles on the disk or tape surface. Uses read-write head mechanism to store and retrieve data Read-write head mechanism in the disk drive records and writes the magnetized particles that represent data. Changing or deleting of data is done by changing the orientation of particles in the disk surface.ext: Adv and Diadv
Magnetic Storage Disadvantages Susceptible to magnetic fields, dust, mold, smoke particles, heat & mechanical problem with the storage device. Gradually lose their magnetic changes resulting in loss of data. Short life span (2 – 20 years) Advantage Newer magnetic storage disks have high storage capacity. Usually cheaper.(?)ext: OpticalStorage
Optical Storage Stores data as microscopic light & dark spots on the disk surface. Uses laser light and it is possible to see the data using high- powered microscope. Disadvantages Several process for writing data Requires software for writing data Slower than hard disk Advantage Strong damage resistance Longer life expectance (20 – 100 years)ext: Factors
Factors for Choosing The BestStorage Technology1. Versatility Accessibility of the medium to different device.2. Durability Susceptibility of the medium3. Speed Access Time Average time it takes for a computer to locate data on the medium and read it. Measures in ms (millisecond) Sequential Access – reads though data from beginning Random Access – “direct access ability to jump to the requsted data. Data Transfer Rate Amount of data that a storage device can move from the storage medium to the computer. Measured in Bps (Bytes per second)
Factors for Choosing The Best Storage Technology 4. Capacity The amount of data that the storage medium could keep. Measured in Bytes. (MB, KB, GB, TB) 5. Cost Amount per megabytes. Storage Term Term Abbreviation Approximate Size Exact Amount Kilobyte KB or K 1 thousand bytes 1,024 bytes Megabyte MB 1 million bytes 1,048,576 bytes Gigabyte GB 1 billion bytes 1,073,741,824 bytes Terabyte TB 1 trillion bytes 1,099,511,627,776 bytesext: FDisk
Magnetic StorageFloppy Disk Technology • Floppy Disk • Floppy Disk Dive
Floppy Disk Small removable, flexible magnetic platter encased in a plastic housing. Made up of of a thin, circular, flexible mylar plastic disk with a magnetic coating. Also referred to as floppies or diskettes.ext: Data Location
Data Location on Floppy Disk A disk drive track is a circular path on the surface of a disk or diskette. A sector is a subdivision of a track on a magnetic disk or optical disc. Each sector stores provides space for 512 bytes (for magnetic disks) or 2048 bytes (for optical discs) of user-accessible data per sector. A cluster is the smallest logical amount of disk space that can be allocated to hold a file. cluster sizes range from 1 sector (512 B) to 128 sectors (64 KB) A - track B – Geometrical Sectors C – Track sector D – Clustersext: Mech Parts
Parts of Floppy Disks Shutter Protects the magnetic disk when not in use. Spring snaps the shutter closed again so no dust or fingerprints can get onto the magnetic disk. Magnetic disk This round piece of plastic is coated with magnetized iron oxide. Hub The metal center of the magnetic disk. The holes in the hub fit over spindles inside the computer and hold the disk in place while it spins. Paper rings glued down to the plastic housing, stay still while the disk spins and clean the disk, removing microscopic bits of dust. Write-protect tab When the hole is open, the disk is locked. Your computer wont allow you to add anything to the disk or erase anything from it. Plastic flap It functions as a simple spring that pushes the paper ring tight against the surface of the magnetic disk.ext: Type of FD
Types of Floppy Disk 3 ½ inch Larger capacity 1.44MB HD / DD 5 ¼ inch Common size before 1987 Capacity – 100K and 1.2MB No longer availableext: Care for FD
Protecting Your Floppy Disk Avoid exposure to heat, cold and magnetic fields. Avoid exposure to dusts, smoke, or water. Do not eject the floppy disk until the light on the front of the drive is off and until all files on the floppy disk have been saved and closed. Always carry disks case or box. Do not touch the surface of the disk. Do not use damage disks or disks with faulty shutter to avoid jamming in the drive. Remember to write protect to avoid accidental erasure of data.ext: Adv and Disadv
Advantages and Disadvantages Advantages: They are very cheap to buy floppy disc drives are very common. Disadvantages: very small storage capacity Susceptible to a lot of damages. Slower The access speed is about 36 KB per second. Not all modern computers have floppy disk drives.ext: FDD
Floppy Disk Drive A device that can read from and write on a floppy disk Can be external or internal Most personal computers have a floppy disk drive, in which you insert and remove a floppy diskext: Parts of FDD
Parts of a Floppy Disk Dive Read/Write Heads: Located on both sides of a diskette used for reading and writing data on the disk. Spindle Motor: engages the metal hub at the center of the diskette, spinning it at either 300 or 360 rotations per minute (RPM). Stepper Motor: move the read/write head assembly to the proper track position. The read/write head assembly is fastened to the stepper motor shaft. Circuit Board: Contains all of the electronics to handle the data read from or written to the diskette.ext: How FDD Works
Floppy Disks Operation How does a floppy disk drive work? Step 1: When you insert the floppy disk into the drive, the shutter moves Step 2: When you Step 1 Step 2 to the side to expose the initiate a disk Step 3: If disk access recording surface on the Step 6 access, the circuit Step writemotor is a instruction, disk. 4:on the drive board A the circuit board causessignals to disk Step 5: the floppy sends A motor verifies whether the to spin. movement control positions the disk can be written to of the read/write read/write heads or not. Step the correct heads The over 6:and the disk. read/write heads location on the Step 5 read data from and recording surface write data on the of the disk. Step 4 floppy disk. Step 3ext: Disk Backup
High Capacity Disk A disk drive that uses disks with capacities of 100 MB and greaterext: HiFD
HiFD HiFD™ (High-Capacity Floppy Disk) drive Uses a 200 MB HiFD™ disk Developed by Sony Electronics, Inc.ext: SuperDisk
SuperDisk Designed to replace regular floppies Can read regular floppies Uses a 120 MB or a 250 MB Super Disk Developed by Imationext: ZipDrive
Zip Drive Uses a Zip® disk that can store 100 MB or 250 MB of data Developed by Iomega Corporation They are stable, inexpensive, and easy to work with yet not the fastest.ext: MO Drive
MO drives Magnetic Optic drives You can only write to it, when it is heated by a laser beam to about 300 degrees Celsius (The Curie point) MO disks are fast, inexpensive, and extremely stable. MO-technology is found in Sonys recordable MiniDisc.
What is a hard disk? Also called a hard drive or a fixed disk A rigid magnetic disk fixed permanently within a drive unit and used for storing computer data Main storage device within a computer. “data center”ext: Cross section
Characteristics of hard disk Consists of several inflexible, circular platters that store items electronically A platter is coated with a material that allows items to be recorded magnetically on its surface. The components of a hard disk are enclosed in an airtight, sealed case to protect them A Hard disk spins around thousands of times per minute(rpm) inside its metal casing, which is why it makes that whirring noise. Capacity is determined by the number of platters. Standard systems come with hard drives between 40Gb and 250Gb. Usually larger, usually faster, usually cheaper and usually fixed. Shock resistant and sealed tightly.ext: Basic Parts
Basic Parts of Hard Disk Platter data/information is written. Read and Write Head read and write/information data on the surface. Actuator mechanism responsible for the movement of RW head for data access. Spindle motor responsible for disk rotationext: Operation
How does a hard disk work? Step 1: The circuit board controls the movement of the Step 1 Step 2 Step 2: A small head activator and a small motor the motor spins plattersWhen the Step 3: while computer is software requests a running disk access,head Step 4: The the read/write heads actuator positions determine the the read/write current or new the head arms over locationlocationdata correct of the on Step 3 the platters to read or write data Step 4ext: Types
Types of Hard Disk External Hard Disk Internal Hard Diskext: Speed
Measuring Speed of Hard Disk Maximum Transfer Rate Highest amount of data that can be transferred per second. 100Mb/s for ATA100 66Mb/s - ATA66 Spindle Rotation Speed The rotation speed of the disk really is the basis of the other two factors of hard disk speed. measured in rpm (revolution/min) usually 5400rpm or 7200 rpm Seek Time The average time it takes for the disk to find the data you need on the platters.ext: Controller
Hard Disk Controllers What is EIDE? What is SCSI? Enhanced Integrated Small Computer System Drive Electronics Interface up to 4 HD w/ up to 8 HD 137GB/disk. Transfer rate 160 Mbps Transfer rate 133 Mbpsext: SATA
Hard Disk Controllers SATA Serial Advance Technology Attachment point to point channel between drive. Transfer rate up to 3GBpsext: Adv and Dis
Advantages and disadvantages Advantages Large storage capacity Faster Data Access Usually fixed inside the computer so cannot get mislaid. Cheapest/MB Can replaced and upgraded. Can have several hard disk on a system unit. Disadvantages Eventually fail Susceptible to contaminants. head crash occurs when read and write head touches the surface of a platter. Not portable.
Caring for your drive1. Protect your drive from excessive jarring and bumping.2. Beware of static.3. Perform periodic checks of your hard disk drive. Disk scanning 1. Logical Scanning 2. Physical Scanning Defragmenting4. Place your hardware in a safe location.5. Make Backups
Optical Medium optical disk / compact disk A flat, round, portable, metal storage medium that usually is 4.75 inches in diameter and less than one-twentieth of an inch thick Common to all modern computers Available in a variety of formats. 1. CD 2. DVDext: CD
Compact Disk Compact Disk originally used to store music, in the form of digital audio, and now used as a data storage device, whence it is called a CD-ROM. holds 650 MB up to 700 MB of data, instructions and information. Developed by Sony and Philips in 1980, mass produced in 1982. A. A polycarbonate disc layer has the data encoded by using lands and pits. B. A reflective layer reflects the laser back. C. A lacquer layer is used to prevent oxidation D. Artwork is screen printed on the top of the disc. E. A laser beam reads the polycarbonate disc, reflected back, and read by the player.ext: How data is written
Compact Discs How does a laser read data on a compact disc? Items are stored using Compact Compact disc disc Compact disc microscopic pits Step 2 Step 31 Step label label label (indentations) and land (flat areas) that are in the middle layer of the disk A laser light reads items from the compact disc pit pitland land lens lens lens lens lens lens Step 1: A laser diode shines 2: If light strikes a pit, 3: Reflected light is it scatters. If light-sensing a light beam light strikes deflected to atoward the land, it is reflected digital compact disc. diode, which sendsback toward of to the computer. signals the1laser diode. prism prism prism 0 prism prism prism 1 Light- Light- Absence of reflected light is sensing sensing read as a digital signal of 0. laser laser laser diode laser laser laser diode diode diode diode diode diode diodeext: Types of CD
Types of CD CD-ROM Compact Disk-Read Only Memory Read-only means you cannot write or save anything on the disk. CD-R Compact-Disk Recordable You can write only once. CD-RW Compact Disk-Rewritable Allows rewriting many times. You must have CD-RW software and a CD-RW drive.ext: Figures
DVD Digital Versatile Disk An extremely high capacity compact disc capable of storing from 4.7 GB to 17 GB Looks just like a CD- ROM but data, instructions, and information is stored in a slightly different manner to achieve a higher storage capacity You must have a DVD- ROM drive or DVD player to read a DVD- ROM.ext: DVD Capacity
Capacity of DVD vs. CD • Three storage techniques used to store DVD-ROM data • Pits are packed closer together to make the disc more dense • Two layers of pits are used, where the lower layer is semitransparent so the laser can read through it to the upper layer • Some are double-sided, which means you can remove the DVD- ROM and turn it over to read the other side Number of Sides 1 2Number of Layers 1 2 1 2Storage Capacity 4.7 GB 8.5 GB 9.4 GB 17 GBext: Caring for CD
Protecting Your Optical Disk Do not expose the disks to excessive heat or sunlight. Do not touch the underside of the disks. Do not write on the underside of the disks. Do not stack the disks on top of one another. Do store the disks in jewel boxes when not in use. Do hold disk by the edges.ext: CD Drives
CD -ROM Drives A device that reads data, instructions and information on a CD-ROM and CD-R. Virtually all modern CD-ROM drives can also play audio CDs as well as Video CDs and other data standards when used in conjunction with the right software.ext: Spped of CD-Rom
CD-R/RW DRIVES Recordable / ReWritable drives also known as burners, writers allow a user to create their own CDs of audio and/or data. great for backup purposes and for creating your own audio CD compilations (not to mention other things like home movies, multimedia presentations, etc.).ext: DVD Drive
DVD-ROM DVD drives can also read CD-ROM drives, so you dont usually need a separate CD-ROM drive. DVD drives have become low enough in price that there isnt much point in purchasing a CD-ROM drive instead of a DVD-ROM drive. “combo drive”ext: DVD Speed