Chap3

1. Using Management Information Systems David Kroenke Hardware and Software Chapter 3

Learn the terminology necessary to be an intelligent consumer of hardware products.

Know the functions and basic features of common hardware devices.

Understand the essentials of the representation of computer instructions and data.

Know the purpose of the CPU and main memory, and understand their interaction.

Understand the key factors that affect computer performance.

Learn basic characteristics of the four most popular operating systems.

Know the sources and types of application software.

Learn about viruses, Trojan horses, and worms and how to prevent them.

Computing devices consists of computerhardwareandsoftware.

Hardware is electronic components and related gadgetry that input, process, output, and store data according to instructions encoded in computer programs or software.

Your personal computer and other computers like it aregeneral-purpose computers.

They can run different programs to perform different functions.

Some computers arespecial-purpose computers.

The programs they run are fixed permanently in memory.

The computer in your cell phone is a special-purpose computer, and so is the computer in your car that meters fuel to your cars engine.

The principles and fundamental components of general-purpose and special-purpose computers are the same;

The sole difference is the computer can process a variety of different programs

One easy way to categorize hardware is by its primary function:

Input hardware

Processing hardware

Output hardware

Storage hardware

Communication hardware

Processing devicesinclude thecentral processing unit (CPU) , which is sometimes called the brain of the computer.

The CPU selects instructions, processes them, performs arithmetic and logical comparisons, and stores results of operations in memory

The CPU works in conjunction withmain memory.

The CPU reads data and instructions from memory, and it stores results of computations in main memory (RAM).

Computers also can havespecial function cardsthat can be added to the computer to augment the computers basic capabilities.

A common example is a card that provides enhanced clarity and refresh speed for the computers video display.

Storage hardwaresaves data and programs.

Amagnetic diskis by far the most common storage device, althoughoptical disks , such as CDs and DVDs are popular.

In large corporate data centers, data are sometimes stored onmagnetic tape .

Computers represent data usingbinary digits , calledbits.

A bit is either a zero or a one.

Bits are used for computer data because they are easy to represent physically.

A computer can be designed so an openswitchrepresents zero and a closed switch represents a one.

Or, the orientation of amagnetic fieldcan represent a bit;

Magnetism in one direction represents a zero

Magnetism in the opposite direction represents aone

Or, foroptical media , small pits are burned onto the surface of the disk so that they will reflect light

In a given spot, a reflection means a one

No reflection means a zero

Computers use bits for two purposes:Instructions and Data

Instructions Add two numbers together

The collection of instructions that a computer can process is called thecomputers instruction set.

Microsoft Intel instruction set.

Macintosh -PowerPC instruction set

In 2006, Apple began offeringMacintosh computers with a choice of either Intel or PowerPC processors.

Currently, you cannot run a program designed for one instruction set on a computer having a different instruction set.

2. Data.

All computer data are represented by bits.

The data can be numbers, characters, currency amounts, photos, recordings, or whatever.

Bits are grouped into 8-bit chunks calledbytes.

For character data, such as letters in a persons name, one character will fit into one byte.

Thus, when you read a specification that a computing device has 100 million bytes of memory, you know that the device can hold 100 million characters.

It is not possible to determine the type of computer data just by looking at the data.

The bit string 01000001 can be interpreted as the decimal number 65, as the character A, or as part of a picture or a sound file.

Further, it could be part of a computer instruction.

The CPU determines how to interpret a bit string from the context in which it encounters it.

If the string occurs in the context of reading instructions, it will be interpreted as a computer instruction.

If it occurs during arithmetic operations, it will be interpreted as the number 65.

Suppose that your IS department states that you can buy three different computer configurations for three different prices.

The computers are described by expressions like the following:

Intel Pentium 4 Processor at 2.8 GHz with 533MHz Data Bus and 512K cache, 256MB RAM

Intel Pentium 4 Processor at 2.8 GHz with 533MHz Data Bus and 512K cache, 512 MB RAM

Intel Pentium 4 Processor at 3.6 GHz with 533MHz Data Bus and 1MB cache, 256 MB RAM

Now, you, have two choices :

You can tell the people in the IS department to specify what they think is best;

Or, with a little bit of knowledge on your part, you can work with the IS department to ask intelligent questions about the relationship of these computers to the kind of work your department does

Themotherboardis a circuit board upon which the processing components are mounted and/or connected.

Thecentral processing unit(CPU)reads instructions and data from main memory, and it writes data to main memory via adata channel,orbus.

Main memoryconsists of a set of cells, each of which holds a byte of data or instruction.

Each cell has an address, and the CPU uses the addresses to identify particular data items.

Main memory is also calledRAM memory , or justRAM.

RAM stands forrandom access memory.

The termrandomis used to indicate that the computer does not need to access memory cells in sequence; rather, they can be referenced in any order.

To store data or instructions, main memory or RAM must have electrical power. When power is shut off, the contents of main memory are lost.

The termvolatileis used to indicate that data will be lost when the computer is not powered.

Main memory isvolatile.

Magnetic and optical disks maintain their contents without power and serve as storage devices.

You can turn the computer off and back on, and the contents of both magnetic and optical disks will be unchanged.

Magnetic and optical disk arenonvolatile.

Memory is used for three purposes:

It holds instructions of the operating system

It holds instructions for application programs such as Excel or Acrobat.

It holds data.

The operating system (OS) is a computer program that controls all of the computers resources

It manages main memory.

It processes key strokes and mouse movements.

It sends signals to the display monitor.

It reads and writes disk files.

It controls the processing of other programs.

Memory swappingoccurs when there is a request to the operating system to store data in memory and the data will not fit because there is not enough free memory to store the requested data.

For this case, the operating system will have to remove or swap something to make space.

Smaller degrees of swapping occurs when:

Your computer has a very large main memory.

You use only one or a few programs at a time.

You use small files.

You may have a serious problem if:

Your computer has a small memory capacity.

You need to use many programs or process many large data files.

Solution - add more main memory!

The CPU reads instructions and data from memory via the data bus.

The maximum speed at which it transfers data is determined by the speed of main memory and the speed and width of the data bus.

A bus that is 16 bits wide can carry 16 bits at a time; one that is 64 bits wide can carry 64 bits at a time.

The wider the bus, the more data it can carry in a given interval of time.

Because the data transfer rate depends on both the width of the data bus and the speed of main memory, another way to speed up the computer is to obtain faster memory.

Some data are accessed more frequently than other data.

Because of this, computer engineers found they could speed up the overall throughput of the CPU by creating a small amount of very fast memory, calledcache memory.

The most frequently used data are placed in the cache.

Typically, the CPU stores intermediate results and the most frequently used computer instructions in the cache.

Each CPU has a clock speed that is measured in cycles per second, or hertz.

A fast modern computer has a clock speed of 3.0 gigahertz (abbreviated GHz), or 3 billion cycles per second.

In general, the faster the clock speed, the faster work will get done.

A fast CPU and data bus are most useful when processing data that already reside in main memory.

Once you have downloaded a large spreadsheet, a fast CPU will rapidly perform complicated, formula-based what-if analyses.

A fast CPU also is useful for processing large graphics files.

Example, manipulating the brightness of the elements of a large picture

If the applications that you or your employees use do not involve millions of calculations or manipulations on data in main memory, then buying the fastest CPU is probably not worthwhile.

Two key performance factors for main memory are speed and size.

Normally, a particular computer make and model is designed to use a given memory type, and the speed for that type is fixed.

There is nothing you can do to increase memory speed.

You can, however, increase theamountof main memory, up to the maximum size of memory that your computer brand and modelcan hold.

If your computer is constantly swapping files, installing more memory will dramatically improve performance.

Memory is cheap and is often the best way to get better performance

Magnetic and optical disks provide long-term, nonvolatile data storage.

The types and sizes of such storage devices will affect computer performance.

Data are recorded on magnetic disks in concentric circles.

The disks spin inside the disk unit, and as they spin magnetic spots on the disks are read or written by theread/write head .

The time required to read data from a disk depends on two measures:

Rotational delaythe time it takes the data to rotate to the data point

Seek time -time it takes the read/write head arm to position the head over the correct circle

There are two kinds of optical disks: CDs (compact disks) and DVD (digital versatile disks).

Both are made of plastic and coated with a photosensitive material.

Bits are recorded by burning a pit into the photosensitive material using a low-power laser.

The presence of a pit causes light to reflect and signifies a one; the absence of reflection signifies a zero.

Nonvolatile

Thepracticaldifferences between CDs and DVDs are capacity and speed.

A typical CD has a maximum capacity of 700 MB, whereas a DVD disk can store up to 4.7GB.

DVD transfer rates about 10 times faster than those for CDs.

There are two types of video display monitors: CRTs and LCDs.

CRT monitorsusecathode ray tubes , the same devices used in traditional TV screens.

dot pitch -the distance between pixels on the screen.

The smaller the dot pitch, the sharper and brighter the screen image will be.

LCD monitorsuse a different technology calledliquid crystal display.

With LCD monitors, no tube is required, so they are much slimmer, around 2 inches or so deep.

pixel pitch- distance between pixels on the screen.

The smaller the pixel pitch, the sharper and brighter the image will be.

Application softwareconsists of programs that perform a business function.

Some application programs are general purpose, such as Excel or Word.

Other application programs are specific

QuickBooks, for example, is an application program that provides general ledger, and other accounting functions.

You can buy computer software several ways:

Off-the-shelf

Off-the-shelf with alterations

Tailor made

Horizontal-market application softwareprovides capabilities common across all organizations and industries.

Word processor, graphics programs, spreadsheets, and all presentation programs are all horizontal-market application software.

Vertical-market application softwareserves the needs of a specific industry.

Examples of such programs are:

Those used by dental offices to schedule appointments and bill patients

Those used by auto mechanics to keep track of customer data and customers automobile repairs

Those used by parts warehouses to track inventory, purchases, and sales

Sometimes organizations developcustom application software.

They develop such programs themselves or hire a development vendor.

Custom development is difficult and risky.

Every application program needs to be adapted to changing needs and changing technologies .

Firmwareis computer software that is installed into devices like printers, print servers, and various types of communication devices.

The software is coded just like other software, but it is installed into special, read-only memory of the printer or other device.

Users do not need to load firmware into devices memory.

Firmware can be changed or upgraded, but this is normally a task for IS professionals.

Computing devices consists of hardware and software.

General-purpose computers can run multiple programs; special-purpose computers, like those in cell phones, run only one program that is fixed in memory.

Hardware can be categorized according to its primary functions: input, processing, output, and storage.

Input hardware includes devices such as keyboards and mice.

Processing hardware includes the CPU and main memory.

Output devices are video displays, printers, and the like.

Storage devices include magnetic and optical disks.

Computers use bits to represent data.

A bit, or binary digit, has a value of zero or one.

Bits are used to represent computer instructions and data.

Four popular operating systems are Windows, Mac, OS, Unix, and Linux.

Computer software consists of the operating system and application software.

Software can be purchased off-the-shelf, purchased off-the-shelf and then altered, or tailor-made.

Types of software include horizontal, vertical, and custom.

Firmware is program code installed in read-only memory of printers or communications devices.

A virus is a computer program that replicates itself and consumes the computers resources.

The program code that causes unwanted activity is called thepayload.

There are many different virus types:

Viruses

Trojan horses

Acomputer virusattaches itself to a program or file so it can spread from one computer to another, leaving infections as it travels. Much like human viruses, computer viruses can range in severity: Some viruses cause only mildly annoying effects while others can damage yourhardware ,softwareorfiles . Almost all viruses are attached to anexecutable file , which means the virus may exist on your computer but it cannot infect your computer unless you run or open the malicious program. It is important to note that a virus cannot be spread without a human action, (such as running an infected program) to keep it going. People continue the spread of a computer virus, mostly unknowingly, by sharing infecting files or sendinge-mailswith viruses as attachments in the e-mail.

Awormis similar to a virus by its design, and is considered to be a sub-class of a virus. Worms spread from computer to computer, but unlike a virus, it has the capability to travel without any help from a person. A worm takes advantage of file or information transport features on your system, which allows it to travel unaided. The biggest danger with a worm is its capability to replicate itself on your system, so rather than your computer sending out a single worm, it could send out hundreds or thousands of copies of itself, creating a huge devastating effect. One example would be for a worm to send a copy of itself to everyone listed in your e-mail address book. Then, the worm replicates and sends itself out to everyone listed in each of the receiver's address book, and the manifest continues on down the line.Due to the copying nature of a worm and its capability to travel across networks the end result in most cases is that the worm consumes too muchsystem memory(ornetworkbandwidth), causing Webservers , network servers and individual computers to stop responding. In more recent worm attacks such as the much-talked-about .Blaster Worm., the worm has been designed to tunnel into your system and allow malicious users to control your computer remotely

ATrojan Horseis full of as much trickery as the mythological Trojan Horse it was named after. The Trojan Horse, at first glance will appear to be useful software but will actually do damage once installed or run on your computer. Those on the receiving end of a Trojan Horse are usually tricked into opening them because they appear to be receiving legitimate software or files from a legitimate source. When a Trojan is activated on your computer, the results can vary. Some Trojans are designed to be more annoying than malicious (like changing your desktop, adding silly active desktop icons) or they can cause serious damage by deleting files and destroying information on your system. Trojans are also known to create abackdooron your computer that gives malicious users access to your system, possibly allowing confidential or personal information to be compromised. Unlike viruses and worms, Trojans do not reproduce by infecting other files nor do they self-replicate.

Prevention steps are:

Find and apply patches to the operating system and to applications.

Never download files, programs, or attachments from unknown Web sites.

Do not open attachments to emails from strangers.

Do not open unexpected attachments to emails, even from known sources.

Run aretroactiveantivirus program at regular intervals, at least once per week.

Antivirus programs

Application software

Binary digit

Cache memory

CD-ROM

CRT monitor

Chap3

Technology

Transcript of Chap3