Think Possibility 2.1 Computer Architecture 2.2 Storage Devices 2.3 Input and Output Devices 2.4 The...

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2.1 Computer Architecture2.2 Storage Devices2.3 Input and Output Devices2.4 The Computing Industry

Unit 2: Hardware Systems

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Unit 2.1: Computer Architecture

•It refers to the design and construction of a computer system.

Computers are classified based on two characteristics:

• What the computer uses for power• How the computer physically represents, processes, stores, and moves data

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Microprocessors

• It is an integrated circuit designed to process instructions.

• It is the most important component of a computer, and usually the most expensive single component.

• It is referred to as “CPU on a chip”

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Microprocessors

How does microprocessor look like?

• It is the largest chip on the motherboard, it can be housed in SEC cartridge or in a square PGA

A PGA is a square chip packaged with pins arranged in concentric squares, typically used for microprocessors.

An SEC cartridge is a popular chip package for

microprocessors.

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Microprocessors

• Inside the chip carrier, a microprocessor is a very complex integrated circuit, containing 50 million miniaturized electronic components.

Functional Areas in a Microprocessor:• Arithmetic Logic Unit - performs arithmetic

and logical instructions. It uses registers to hold data that is being processed.

• Control Unit - fetches each instruction. It gives signal to begin processing.

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What does the CPU look like?

INTEL Pentium 4

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What does the CPU look like?

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Microprocessors

Performance Factors1. Clock Speed

Microprocessor Clock - a timing device that sets the pace for executing instructions

Microprocessor Speed Specification:• Megahertz (MHz) - million cycles per second• Gigahertz (GHz) - billion cycles per second

Cycle - the smallest unit of time in a microprocessor’s universe.

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Microprocessors

2. Word Size

• It refers to the number of bits that a microprocessor can manipulate at one time• It is based on the size of the registers in the ALU and the capacity of circuits that lead to those registers.

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Microprocessors

3. Cache Size

• It is sometimes called “RAM Cache” or “Cache memory”

• It is a special high-speed memory that allows a microprocessor to access data more rapidly than from other memory

Types of Cache:• Level 1 Cache - built into processor chip• Level 2 Cache - located on a separate chip and

takes a little more time to get data to the processor

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Microprocessors

4. Instruction Set

CISC - Complex Instruction Set Computer. It is a general-purpose microprocessor chip designed to handle a wider array of instructions.

RISC - Reduced Instruction Set Computer. It is a microprocessor chip designed for rapid and efficient processing of a small set of simple instructions.

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Microprocessors

5. Processing Techniques

Serial Processing - the processor must complete all of the steps in the instruction cycle before it begins to execute the next instruction.

Pipelining - a processor can begin executing an instruction before it completes the previous instruction.

Parallel Processing - multiple instructions are executed at the same time.

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Random Access Memory

• It is a temporary holding area for data, application program instructions, and the operating system

• It is one of the most expensive computer component• It is the waiting room for the computer’s processor• It holds raw data and program instructions• It holds the results of processing until they can be

stored in a disk or tape• It is volatile, which means that it requires electrical

power to hold date• RAM speed is expressed in nanosecond (ns) and in

MHz

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How does RAM work?

• Capacitors hold the bits that represent data

• A charged capacitor is “turned on” and represents a “1” bit

• A discharged capacitor is “turned off” and represents a “0” bit

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Basic Types of RAM:

• DRAM - Dynamic RAM. A type of physical memory used in most personal computers. The term dynamic indicates that the memory must be constantly refreshed (reenergized) or it will lose its contents.

• SRAM - Static RAM. SRAM is a type of memory that is faster and more reliable than the more common DRAM (dynamic RAM). SRAM can give access times as low as 10 nanoseconds. In addition, its cycle time is much shorter than that of DRAM because it does not need to pause between accesses. Unfortunately, it is also much more expensive to produce than DRAM. Due to its high cost, SRAM is often used only as a memory cache.

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RAM is usually configured as a series of DIPs soldered onto a small circuit board called:

• DIMM - Dual In-Line Memory Module• RIMM - Rambus In-Line Memory Module• SORIMM - Small Outline Rambus Memory Module

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Read-Only Memory

Difference of RAM and ROM:

• ROM is a type of memory circuitry that holds the computer’s startup routine

• ROM is housed in a single integrated circuit and is usually a fair, large, caterpillar-like DIP package which is plugged into the motherboard

• RAM is temporary and volatile, while ROM is permanent and non-volatile

• ROM holds “hard-wired” instructions that remain in place even when the computer power is turned off.

• The instructions in ROM are permanent

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Read-Only Memory

Importance of ROM:

• It contains a small set of instructions called the ROM BIOS (basic input/output system)

• These instructions tell the computer how to access the hard disk, find the OS, and load it into RAM

• Once OS is loaded, the computer can understand your input, display, output, run software, and access your data

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CMOS Memory

• Complementary Metal Oxide Semiconductor Memory

• It is a type of chip that requires very little power to hold data.

• It can be powered by a small, rechargeable battery integrated in the motherboard

• It can retain vital data about computer system configuration even when your computer is turned off

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Unit 2.2 Storage Devices

Two main components of a Data Storage System:

• Storage Medium - contains data• Storage Devices - mechanical apparatus that records and retrieves data from the storage medium

Storage Technology - refers to the storage device and the media it uses

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Storage Devices

How does a storage system interacts with other computer components?

• Data gets copied from a storage device into RAM, where it waits to be processed• After data is processed, it is stored temporarily in RAM, but it is copied to a storage medium for permanent safekeeping

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Storage Devices

Writing Data or Saving a File - process of storing data

Reading Data, Loading Data, or Opening a File - process of retrieving data

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Storage Devices

Difference between a Magnetic Storage and Optical Storage:

Magnetic Storage:

• Stores data by magnetizing microscopic particles on the disk or tape surface• The particles retain their magnetic orientation until that operation is changed, making disks and tapes fairly permanent but modifiable storage media• Examples are hard disk, floppy disk, and tape storage technologies• Data stored on magnetic media such as floppy disks can be altered by magnetic fields, dust, mold, smoke particles, heat, and mechanical problems with the device

Read-Write head mechanism - reads and writes the magnetized particles that represent data

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Storage Devices

Optical Storage:

• It stores data as microscopic light and dark spots on the disk surface

• The dark spots are called pits and the lighter, non-pitted surface areas of the disk are called lands

• Data is read using a laser light and it is possible to see the data using a high-powered microscope

• Transition between pits and lands is interpreted as 0’s and 1’s

• It uses a low-power laser light to read the data • It is less prone to environmental damage

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Storage Devices

Criteria for comparing storage devices:

1. Versatility

• Some storage devices can access data from one type of medium but some devices can access data from several media

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Storage Devices

2. Durability

• Some storage devices are prone to damage from mishandling or other environmental factors and some storage devices are less prone than others.

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Storage Devices

3. Speed

• Fast access to data is important • Access time-the average time it takes a computer

to locate data on the storage medium and read it• Random Access - also called “Direct Access” is

the ability of a device to access directly the requested data

• Sequential Access - reading and writing data from the beginning of the medium

• Data transfer Rate - amount of data that a storage device can move from the storage medium to the computer per second

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Storage Devices

4. Capacity

• In today’s technology, higher capacity is almost always preferred

• Storage capacity-maximum amount of data that can be stored on a storage medium

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Floppy Disk Technology

Floppy disk-a round piece of flexible Mylar plastic covered with a thin layer of magnetic oxide and sealed inside a protective casing. It is a portable inexpensive storage medium that consists of a thin, circular, flexible plastic disk with a magnetic coating enclosed in a square shaped plastic shell.

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• Floppy Disk-3 ½ size and 1.44 MB capacity

• A device that records and retrieves data on a floppy disks

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Zip Disks

• Manufactured by Iomega

• Capacities available are 100MB and 250MB

• Requires special disks drives

• Transportable and provides more storage capacity

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Superdisks

• Manufactured by Imation

• Capacity is 120MB• It provides an

alternative high capacity, transportable storage option

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Advantage:

• Portability

Disadvantage:

• Speed

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Hard Disk Technology

Why hard disk drives so popular?

• Provides large storage capacity• Provides faster access• Economical

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How does hard disk works?

• It has one or more platters and their associated read-write heads

• The driver spindle supports one of more hard disk platters• Both sides of the platter are used for data storage. So more

platters mean more storage• Hard disk platters rotate as a unit on the spindle to position

the read-write heads over specific data• The platters spin continuously, making thousands of

rotations per minute.

Hard disk platter - flat, rigid disk made of aluminum or glass and coated with magnetic iron oxide particles. It is stored inside the drive case or cartridge to prevent dust and other contaminants from interfering with the read-write head

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Controller-a circuit board which is included in the hard drive mechanism that positions the disk and the read-write heads to locate data

Classification of Disk Drives According to Controller:

• Ultra AT Attachment (ATA) and Enhanced Integrated Drive Electronics (EIDE) use the same basic drive technology and both feature high storage capacity and fast data transfer. Ultra ATA drives are twice as fast as their EIDE counterparts.

• Small Computer System Interface (SCSI) drives provide a provide a slight performance advantage over EIDE drives and found in high-performance workstations and servers

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The storage technology used on many PCs transfers data from a disk, through the controller, to the processor, and finally to the RAM before it is actually processed.

A relatively new technology called Direct Memory Access (DMA) allows computer to transfer data directly from a drive into RAM, without processor intervention.

Ultra DMA(UDMA) is a faster version of DMA.

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Hard disks are not as durable as many other storage technologies.

Head crash damages some of the data on the disk. It happens when the read-write head runs into a dust particle or some other contaminant on the disk. Head crash can also be triggered by jarring the hard disk while in use.

Hard disk is sealed in a case to help eliminate contaminants from contacting the platters and causing head crashes.

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What is RAID?

• Redundant Array of Independent Disks• A RAID storage device contains many disk

platters, provides redundancy, and achieves faster data access than conventional hard disks

• The redundancy feature protects data from media failures by recording the same data on more than one disk platter.

• RAID is a popular option for mainframe and server storage, but less popular for PC

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Tape Storage

A tape backup is a copy of the data on hard disk, which is stored on magnetic tape and used to restore lost data. It is relatively inexpensive and can rescue from the overwhelming task of trying to reconstruct the lost data.

A tape is sequential, rather than random-access, storage medium. Data is arranged in a long sequence of bits that begins at one end of the tape and stretches to the other end.

A tape cartridge is a removable magnetic tape module similar to cassette tapes. The beginning and head of each file are marked with special “header labels.”

To locate a file, the tape drive must start at one end of the tape and read through all of the data until it finds the right header label. Access time is measured in slow seconds.

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Tape Storage

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CD Technology

CD-ROM

• Compact Disk Read-Only Memory is based on the same technologies as audio CDs

• A computer CD-ROM contains data that was stamped on the disk surface when it was manufactured.

• CD-ROM technology provides storage capacity that far exceeds that of a floppy or Zip disk. A single CD-ROM holds up to 680MB equivalent to more than 300,000 pages of text.

• The surface of the disk is coated with a clear plastic, making the disk durable

• A 24X CD-ROM Drive would transfer at a rate of 24 X 150KB or 3600 KB per second.

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CD Technology

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CD Technology

CD-Writer Technologies:

• Compact Disc Recordable (CD-R) – records data on a special CD-R disk. As a result, the data on the disk is not actually stored in pits. Dark spots in the dye layer, play the same role as pits to represent data and allow the disks that you create to be read not only by CD-R drive, but also by CD-ROM and DVD Drive.

• Compact Disc Rewritable (CD-RW) – allows you to write data at a later time. The progress requires special CD-RW disks and a CD-RW drive, which uses phase change technology to alter the crystal structure on the disk surface. Altering the crystal structure creates patterns of light and dark spots.

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DVD Technology

• Digital Video Disc or Digital Versatile Disc• It is a variation of CD Technology that was

originally designed as an alternative to VCRs but quickly adopted by the computer industry

• A computer’s DVD drive can read disks contain computer data often called DVD-ROM disks, as well as disks that contain DVD movies sometimes called DVD-Video disks.

• It is a new type of CD-ROM that holds a minimum of 4.7GB (gigabytes), enough for a full-length movie. The DVD specification supports disks with capacities of from 4.7GB to 17GB

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DVD Technology

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Unit 2.3 Input and Output Devices

Data Bus – where data travels from one component to another over circuits. One part of the data bus runs between RAM and the microprocessor and another is between RAM and various storage devices.

Expansion Bus – the segment of the data bus that extends between RAM and peripheral devices. As data moves along the expansion bus, it may travel through expansion slots, cards, ports, and cables.

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Input and Output Devices

Expansion Slots – a long, narrow socket on the motherboard into a which you can plug an expansion card.

Expansion Card – a small circuit board that provides a computer with the ability to control a storage device, an input device, or an output device. It is also called expansion boards, controller cards, or adapters.

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Major Types of Expansion Cards:

• Industry Standard Architecture (ISA) Slots – old technology slots used for some modems and other slow devices. Many new computers have few or no ISA slots.

• Peripheral Component Interconnect (PCI) Slots – offer fast transfer speeds and a 32-bit or 64-bit data bus. These slots typically house a graphics card, sound card, video capture card, modem, or network interface card.

• Accelerated Graphics Port (AGP) – provides a high-speed data pathway that is primarily used for graphics card.

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AGP, PCI, and ISA slots are different lengths

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Most notebook computers are equipped with a special type of external slot called PCMCIA slot (Personal Computer Memory Card International Association). The slot can hold more than one PC Card.

Classification of PCMCIA slots according to thickness:• Type I slots – accept only the thinnest PC cards, such as memory expansion cards• Type II slots – accept most of the popular PC cards-those that contain modems, sound cards, and network cards• Type III slots – commonly included with today’s notebook computers and accept the thickest PC cards, which contain devices such as hard disks drives

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Expansion Port

• Any connector that passes data in and out of a computer or peripheral device.

• Ports are also called “jacks” or “connectors”

• It is often housed on an expansion card so that it is accessible through an opening in the back of the computer’s system unit

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Display Devices

Keys to Computer Display:

• Graphics Card – also called a graphics board or video card contains circuitry that generates the signals for displaying an image on the screen. It also contains special video memory, which stores screen image as they are processed before they are displayed

• Display Device – example is monitor

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Display Devices

Difference between CRT and LCD:

• Cathode Ray Tube (CRT) – uses gun-like mechanisms to direct beams of electrons toward the screen and activate individual dots of color that form an image. CRT monitors are inexpensive and offers dependable computer display.

• Liquid Crystal Display (LCD) – produces an image by manipulating light within a layer of liquid crystal cells. The advantages of LCD monitor include display clarity, low radiation emission, portability, and compactness

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Display Devices

Factors affecting Image Quality:

• Screen size• Dot pitch – measure of image clarity• Resolution – maximum number of

horizontal and vertical pixels displayed on the screen

• Color depth – the number of colors that a monitor and graphics card can display

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Printers

A device that prints text or illustrations on paper. There are many different types of printers.

Factors affecting Print Quality and Price of Printers:

• Resolution – where the quality or sharpness of printed images and text depends. Printer resolution is measured by the number of dots it can print per linear inch, dpi.

• Print Speed – measured either by pages per minute (ppm) or characters per second (cps)

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Printers

Types of Printers:

• Ink Jet Printer• Solid Ink Printer• Thermal Transfer Printer• Dye Sublimation Printer• Laser Printer• Dot Matrix Printer

Think Possibility 2.1 Computer Architecture 2.2 Storage Devices 2.3 Input and Output Devices 2.4 The...

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Transcript of Think Possibility 2.1 Computer Architecture 2.2 Storage Devices 2.3 Input and Output Devices 2.4 The...