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Input, Output, and Storage Devices

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Operating Systems and Devices: An Overview

• The operating system must:

– Handle input from the keyboard, mouse, and other input devices

– Handle output to the screen, printer, and other output devices

– Control information storage and retrieval using various types of disk drives

– Support communications with remote computers

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Software Considerations

• The operating system provides the basic input/output support for the parallel, serial, or other ports your printer and other hardware use, but it doesn’t support specific features of individual devices you may connect to these ports

• For that, you need a driver, which may be supplied by the hardware manufacturer or the producer of the operating system

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Standard Input Devices

• There are two standard and universal computer input devices: the keyboard and the mouse

• Because the input/output routines for the mouse and keyboard are highly standardized across operating systems, it is unlikely that you will need to interact with the operating system to set up these devices

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Mouse and Keyboard Drivers

• The main difference between your mouse and keyboard and another device you may connect to your computer is virtually universal standardization

• Newer operating systems include fairly sophisticated keyboard driver routines and custom configuration utilities, such as the one from Windows 2000

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Other Input Devices

• If you do graphics design, web page

development, digital photography, play

games, movie or sound editing, then you

will use one or more specialty input

devices, such as digital tablets, scanners,

joysticks and gamepads, digital sound

input, or digital picture and video input

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Firewire IEEE 1394

• IEEE 1394 is the specification for a digital interface, that supports data communication at 100, 200, or 400 megabits per second

• This technology is currently targeted at multimedia peripherals, which include digital camcorders and external hard drives

• Firewire, invented by Apple is being eclipsed by a new USB standard USB 2.0

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USB 2.0

• Max Transfer Rate 480mbps or 60MB/sec

• Backwardly Compatible with USB 1.1

• Rapid Industry Adoption

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Printers

• A printer is an important part of nearly

every computer installation

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Printer Types

• The following types of printers are the most popular today:

– Dot matrix printers, which produce characters by slamming a group of wires (dots) from a rectangular grid onto a ribbon and then onto paper to produce characters

– Ink-jet printers, another printer that creates characters from dots by squirting tiny droplets of ink directly onto the page

– Laser printers use an imaging technology similar to copiers to produce computer output, and are probably the most popular printer design for business text and graphics

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Printer Types

• Asides from the three major printer types, there are some other printer designs that are used in specialized arenas:

– Line printers, one of the earliest impact printer designs, print an entire line at a time rather than a character at a time

– Thermal-wax transfer printers. Two basic thermal-wax transfer designs exist. One rolls plastic film coated with colored wax and the other is known as phase change

– Dye sublimation printers don’t just melt pigments and spray them onto the paper, they vaporize them

– Imagesetter printers, high-quality output devices frequently used in the printing industry to produce final output or to page masters for offset printing

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Printer Types

• In addition to traditional printers, another printer-like device called a plotter is popular in engineering architecture, and other fields where hard copy output (such as blueprints) won’t fit on standard paper sizes, or can’t be produced by standard character or graphics printers

• Plotter design is even more complex than printers, using pen and control mechanisms

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Printer Connections

• In the early days of computing, nearly all printers were connected to a serial port—the same port where you may connect your modem or mouse today

• Today, the most common PC printer connection is via a parallel or USB port, which manages communications between the computer and peripherals

• The parallel port is sometimes called a Centronics interface, after the printer manufacturer that made it popular

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Printer Connections

• Extended capability port (ECP) communication allows for higher speed bidirectional communication between the computer and printer, as well as the printer and computer

• The Universal Serial Bus (USB) interface is very popular in today’s printer market

• Almost all printers now come with a USB port built into the printer

• Apple computers are also supplied with USB connectivity, but older Apple machines use a slower, similar technology, the Apple Desktop Bus (ADB)

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Display Adapters

• The general industry acceptance of the AGP (Accelerated Graphics Port) bus standard has enabled adapter manufacturers to supply one hardware product, or a line of hardware products, to a variety of hardware platforms

• The AGP bus enables high-performance graphics capabilities

• AGP 4x is standard 8x is out and gaining support

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Basic Display Adapter Technology

• If you are using a PC with a monitor, you have a display adapter card already installed in your computer

• No matter what computer platform you are using, the basic display (and the baseline standard in most cases) consists of 640 pixels horizontally and 480 pixels vertically

• A pixel is a picture element, actually a small dot of light that represents one small portion of your overall screen display

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Basic Display Adapter Technology

• Top-end display adapters are easily capable of displaying 1280 x 1024 pixels, 1600 x1280, or even 2048 x 1536 in some cases

• In general, as you display more pixels on the screen, you’ll need a larger monitor to comfortably read the displayed data

• A resolution of 640 X 480 simply means that images are displayed with 640 dots of light from left to right and 480 dots of light top to bottom

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Installing Display Adapters

• There can be good reasons for upgrading display hardware

• Technology changes, software changes, and our personal needs change, all leading to potential upgrade situations

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Installing Display Adapters

• The majority of display adapters are supplied as AGP cards

• The AGP bus has become a popular standard among computer hardware manufacturers, including Intel-based computers, Macintosh computers, and workstations designed for UNIX, Sun Solaris, and other systems

• Installing any display adapter bus card is similar to installing any other circuit boards

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Installing Circuit Boards

• To avoid damage to circuit boards during installation, follow these simple guidelines:

– Leave the card inside its protective cover until you are ready to install it

– Disconnect all power to the computer

– Prepare the computer by removing the case and any slot covers for the slots you will use

– Position the card inside its cover, near the computer

– Touch a grounded part of the computer

– Insert the card carefully into the chosen slot and press it firmly into place

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Sound Cards

• You’ll find that support for a sound card is automatic with new computers

• Sound devices are of two general types: bus cards and hardware integrated with the motherboard

• Increasingly you will see sound cards built into the motherboard

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Other Output Devices

• Digital video is becoming a popular consumer and professional computer-based feature

• Adapter cards that let you capture and output digital video to a camera or VCR are available, coupled with capable, low-cost video editing software to help you use them

• Enhanced sound output is also now reasonably priced

• You can output (and input) a digital audio stream to minidisk or DAT (Digital Audio Tape) recorders, CDs or even DVDs

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Computer Storage Options

• Most computer systems are supplied with a single 3.5-inch floppy drive, perhaps a high-density floppy or Zip disk, one or more internal, fixed hard drives, and a CD-ROM or DVD drive

• The most popular hard drive interface in the Intel PC architecture is the Integrated Drive Electronics (IDE) interface

• A single IDE interface can support two devices, one so-called master (the first or main drive) and one slave (secondary storage device)

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Computer Storage Options

• The cable usually has three 40-pin header connectors

• Enhanced IDE (EIDE) supports transfer speeds as high as 22 megabits per second

• The last type of drive, which can be used on all PC platforms to mention, is the type that uses the Small Computer System Interface (SCSI)

• SCSI can be a confusing standard, partially because there are so many different SCSI designs, each with its own set of cables and rules

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RAID Arrays

• To address some of issues, a group of researchers at the University of California in Berkeley introduced the concept of a Redundant Array of Inexpensive Drives (RAID)

• RAID arrays serve three purposes: increased reliability, increased storage capacity, and increased speed

• Different levels of RAID focus on different purposes, and there is no RAID level that can be declared superior for all situations

• RAID is implemented as a combination of hardware and software

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Compact Disk (CD) Technology

• CD-ROMs are very important in today’s operating system environment because most software and documentation are distributed on this media

• These disks are different from floppies and hard disks for many reasons, including the way data is stored

• CD-ROMs use a big “spiral” that starts at the inside of the disk and winds itself slowly toward the outside of the disc

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Compact Disk (CD) Technology

• The disc itself is rotated by a precision motor that keeps the disc speed constant

• The optical pickup is typically moved by yet another motor under computer control

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Digital Versatile Disc (DVD) Technology

• The digital versatile disc, or DVD, works a lot like the CD-ROM

• The DVD disc can have two sides with up to two layers per side

• All data on a hard disk, floppy disk, or CD-ROM is stored on one layer of material

• On the CD-ROM, when laser light hits the layer, it is reflected

• On a DVD, the same thing happens, but in addition to the first layer, which is a spiral that moves from the middle of the disk to the outside like a conventional CD-ROM, the DVD disk has a second layer

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CD-ROM and DVD-ROM Interfaces

• CD-ROM and DVD-ROM drives are typically connected to the computer using a hard disk interface

• Most PCs use the IDE interface with SCSI as a close second

• The latest generation of PCs have drivers for CD-ROM and DVD-ROM drives built into the ROM BIOS, which allows them to use the drives without special drivers

• This enables them to boot an operating system directly from a CD-ROM or DVD-ROM

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Recordable and Rewritable CD and DVD

• CD-R and DVD-R can record data once on the media, and then it can be read many times

• Thus, the R stands for recordable

• CD-RW and DVD-RW can write on the media thousands of times

• RW stands for rewritable

• Currently, these devices can record up to 4.7 GB per side, depending on the manufacturer

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Connecting Drives

• All of the drives discussed in this presentation connect to the computer in much the same way as hard disks, typically through an IDE or SCSI standard

• The drivers needed for many of these drives are often quite specialized

• It is very important to make sure you have the drivers required for the operating system with which you want the drives to function