MIS Chapter 4

keyboards

flatbed plotter

four

bits

byte

megabyte

terabyte

kilobyte

the main memory

bus

operating system

place the new data into unused memory

hertz

It cannot effectively utilize more than 4GB of main memory

volatile

cache

magnetic disk

They have software that enables them to connect to a network.

It is typically accessed from another computer via a network

a server farm

Both client and server computers need an operating system.

Linux

Windows

server operating systems

Virtualization

just buys a license to use the product

horizontal-market application

vertical-market application software

a desktop program

thin-client applications

They generally have more features and functions than thin-client applications

An organization can tailor its applications to fit its requirements

Firmware

A) Bytecode

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T

T

F

T

F

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F

T

T

F

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T

F

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T

F

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F

In a generic computer, hardware consists of electronic components and related gadgetry that input, process, output, and store data according to instructions encoded in computer programs or software. Typical input hardware devices are the keyboard, mouse, document scanners, and bar-code scanners. Processing devices include the central processing unit (CPU), which is sometimes called "the brain" of the computer. The CPU works in conjunction with main memory. Main memory is sometimes called RAM, for random access memory. Output hardware consists of video displays, printers, audio speakers, overhead projectors, and other special-purpose devices. Storage hardware saves data and programs. The magnetic disk is still the most common storage device, although solid state drives may soon replace them.

All computer data are represented by bits. The data can be numbers, characters, currency amounts, photos, recordings, etc. All are simply a string of bits. Bits are grouped into 8-bit chunks called bytes. For character data, such as the letters in a person's name, one character will fit into one byte. Bytes are used to measure sizes of noncharacter data as well. For example, a given picture can be said to be 100,000 bytes in size. This statement means the length of the bit string that represents the picture is 100,000 bytes or 800,000 bits (because there are 8 bits per byte). The specifications for the size of main memory, disk, and other computer devices are expressed in bytes. A kilobyte, abbreviated K, is a collection of 1,024 bytes. A megabyte, or MB, is 1,024 kilobytes. A gigabyte, or GB, is 1,024 megabytes; a terabyte or TB, is 1,024 gigabytes; a petabyte, or PB, is 1,024 terabytes; an exabyte, or EB, is 1,024 petabytes; and a zetabyte, or ZB, is 1,024 exabytes.

The CPU (central processing unit) is the major actor in a computer. To run a program or process data, the computer must first transfer the program or data from disk to main memory. Then, to execute an instruction, it moves the instruction from main memory into the CPU via the data channel or bus. The CPU has a small amount of very fast memory called a cache. The CPU keeps frequently used instructions in the cache. The main memory of the computer contains program instructions for application programs and a browser. It also contains instructions for the operating system. Main memory is too small to hold all of the programs and data that a user may want to process. Consequently, the CPU loads programs into memory in chunks. If the user opens another program or needs to load more data, the operating system will direct the CPU to attempt to place the new program or data into unused memory. If there is not enough memory, it will remove something, and then it will place the just-requested program or data into the vacated space. This process is called memory swapping.

Users employ client computers for word processing, spreadsheets, database access, and so forth. Most client computers also have software that enables them to connect to a network. Servers provide some service. Some servers process email; others process Web sites; others process large, shared databases; and some provide all of these functions or other, similar functions. They usually have multiple CPUs. Servers typically have limited video displays. Many servers have no display at all, because they are only accessed from another computer via a network. For sites with large numbers of users, servers are organized into a collection of servers called a server farm.

Every computer has an operating system, which is a program that controls that computer's resources. Some of the functions of an operating system are to read and write data, allocate main memory, perform memory swapping, start and stop programs, respond to error conditions, and facilitate backup and recovery. In addition, the operating system creates and manages the user interface, including the display, keyboard, mouse, and other devices. Although the operating system makes the computer usable, it does little application-specific work. Application programs are software that are processed on the client or server computer. If you want to check the weather or access a database, you need application programs such as an iPad weather application or Oracle's customer relationship management (CRM) software.

A particular operating system is written for a particular type of hardware. For example, iOS works only on the iPhone and iPad hardware. Mac OS X works only on the Mac. However, in some cases, multiple versions of the operating system are available for different computer types. Second, application programs are written to use a particular operating system. Because applications only run on particular operating systems, it is important to create multiple versions for different types of devices.

The four major operating systems are Windows, Mac OS, Unix, and Linux. 1. The most popular is Microsoft Windows. Some version of Windows resides on more than 85 percent of the world's desktops, and when considering just business users, the figure is more than 95 percent. The most recent client version of Windows is Windows 8, a major re-write of prior versions. 2. Apple Computer, Inc., developed its own operating system for the Macintosh, Mac OS. The current system is Mac OS X Mountain Lion. Macintosh computers are used primarily by graphic artists and workers in the arts community. 3. Unix is an operating system that was developed at Bell Labs in the 1970s. It has been the workhorse of the scientific and engineering communities since then. 4. Linux is a version of Unix that was developed by the open source community. This community is a loosely coupled group of programmers who mostly volunteer their time to contribute code to develop and maintain Linux. The open source community owns Linux, and there is no fee to use it. Linux can run on client computers, but is by far most popular as a server OS.

: Virtualization is the process by which one computer hosts the appearance of many computers. One operating system, called the host operating system, runs one or more operating systems as applications. Those hosted operating systems are called virtual machines (vm). Each virtual machine has disk space and other resources allocated to it. The host operating system controls the activities of the virtual machines it hosts to prevent them from interfering with one another. With virtualization, each virtual machine is able to operate exactly the same as it would if it were operating in a stand-alone, nonvirtual environment. For example, with virtualization one server can support two instances of Windows Server, one instance of Linux, and three instances of Windows

When a person buys a computer program, it does not mean actually buying that program. Instead, he is buying a license, which is the right to use the program. Large organizations do not buy a license for each computer user. Instead, they negotiate a site license, which is a flat fee payment for the right to install the product (operating system or application) on all of that company's computers or on all of the computers at a specific site.

Linux is a version of Unix that was developed by the open source community. In case of Linux, no company can sell a license to use it. It is owned by the open source community, which states that Linux has no license fee (with certain reasonable restrictions). Large companies such as IBM, and smaller companies such as RedHat can make money by supporting Linux, but no company makes money selling Linux licenses.

Application software consists of programs that perform a service or a function. Some application programs are general purpose. Other application programs provide specific functions. 1. Horizontal-market application software provides capabilities common across all organizations and industries. Word processors, graphics programs, spreadsheets, and presentation programs are all horizontal-market application software. Examples of such software are Microsoft Word, Excel, and PowerPoint. 2. Vertical-market application software serves the needs of a specific industry. Examples of such programs are those used by dental offices to schedule appointments and bill patients. Vertical applications usually can be altered or customized. 3. One-of-a-kind application software is developed for a specific, unique need. The IRS develops such software, for example, because it has needs that no other organization has.

Organizations develop custom application software themselves or hire a development vendor. By developing custom software, an organization can tailor its application to fit its requirements. Custom development is difficult and risky. Staffing and managing teams of software developers is challenging. Managing software projects can be daunting. Many organizations have embarked on application development projects only to find that the projects take twice as long-or longer-to finish than planned. For custom-developed software, the using company must pay all of the adaptation costs itself. Over time, this cost burden is heavy.

: Firmware is computer software that is installed into devices such as 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. In this way, the program becomes part of the device's memory; it is as if the program's logic is designed into the device's circuitry. Users do not need to load firmware into the device's memory. Firmware can be changed or upgraded, but this is normally a task for IS professionals. The task is easy, but it requires knowledge of special programs and techniques that most business users choose not to learn.

The term open source means that the source code of the program is available to the public. Source code is computer code as written by humans and that is understandable by humans. Source code is compiled into machine code that is processed by a computer. Machine code is, in general, not understandable by humans and cannot be modified. In a closed source project, say Microsoft Office, the source code is highly protected and only available to trusted employees and carefully vetted contractors. The source code is very well protected. Only those trusted programmers can make changes to a closed source project. With open source, anyone can obtain the source code from the open source project's Web site. Programmers alter or add to this code depending on their interests and goals. In most cases, programmers can incorporate open source code into their own projects. They may be able to resell those projects depending on the type of license agreement the project uses. Open source succeeds because of collaboration. A programmer examines the source code and identifies a need or project that seems interesting. He or she then creates a new feature, redesigns or reprograms an existing feature, or fixes a known problem. That code is then sent to others in the open source project who then evaluate the quality and merits of the work and add it to the product, if appropriate.