RESUME COMPUTER SYSTEM

RESUME
CHAPTER 2
COMPUTER SYSTEM
Mata Kuliah
Sistem Informasi Manajemen
Dosen Pengampu : Drs. Yong Dirgiatmo M.Sc

Grup 4 :
Alifia Faizun Nahari F1314008
Indah Nur Fayakun F1314049
Rizki Darin F1314077

FAKULTAS EKONOMI DAN BISNIS
UNIVERSITAS SEBELAS MARET
SURAKARTA
2015


COMPUTER SYSTEMS

BASIC COMPONENTS OF COMPUTER SYSTEMS
There are two distinct types of computers:
Digital Digital computers operate directly on numbers, or digits, just as humans do.
Analog Analog computers manipulate some analogous physical quantity, such as voltage or shaft rotation speed, which represents the numbers involved in the computation.
Digital machines have largely replaced the analog computers in current situations, thus, the discussion in this summary relates to digital computers.
Underlying Structure
All computers are made up of the same set of six building blocks: input, output, memory, arithmetic/logical unit, control unit, and files. There are two blocks together are often referred to as the Central Processing Unit (CPU) or as the processor, these are arithmetic/logical unit and control unit.
Input / Output
Terminal It is designed strictly for input/output and does not incorporate a CPU, or at least not a general-purpose processor. The terminal is connected to a computer via some type of communication line. Most terminals consists of a keyboard for data entry and a monitor to show the user what has been entered and to display the output from the computer.
Computer Memory
Computer memory is divided into cells, and a fixed amount of data can be stored in each cell. Further, each memory cell has an identifying number, called an address, which never changes. A memory cell that can store only one character of data is called a byte, and a memory cell that can store two or more characters of data is called a word.
Each memory cell consists of a particular set of circuits, and each circuits can be set to either "on" or "off." Because each circuit has just two states, they have been equated to the two possible values of a binary number. Thus, each circuit corresponds to a binary digit, or a bit.
Arithmetic / Logical Unit
The arithmetic/logical unit consists of incredibly small integrated circuits on a silicon chip. It has been built to carry out addition, subtraction, multiplication and division, as well as to perform certain logical operations such as comparing two numbers for equality or finding out each number is bigger.


Computer Files
As applications are being processed on a computer, the data required for the current computations must be stored in the computer memory. File devices include magnetic tape drives, hard or fixed drives, removable disk drives, flash drives, and CD or DVD (optical) drives. All but the optical drives record data by magnetizing spots on the surface of the media, using a binary coding scheme.
Two basic ways to organize computer files:
Sequential access files All of the records that make up the files are stored in sequence according to the file's control key. It is usually stored on magnetic tape, is the file device that stores data on tape and that retrieves data from tape back into memory.
Direct access files Stored on a direct access storage device (DASD), is a file from which it is possible for the computer to obtain a record immediately, without regard to where the record is located in the file. There are several types of direct access devices, including hard drives, removable disk drives, CD and DVD drives, and flash drives.

Control Unit
The control unit is the key, it provides the control that enables the computer to take advantage of the tremendous speed and capacity of its other components.
THE STORED-PROGRAM CONCEPT
The complete listing of what is to be done for an application is called a program, and each individual step or operation in the program is called an instruction. The control unit carries out the program, one step or instruction at a time, at electronic speed.
TYPES OF COMPUTER SYSTEMS
Microcomputers Often called micros or personal computers or just PCs. They generally have less power than midrange systems, but the dividing line between these categories is faint. In general, microcomputers can be carried or moved by one person and the usually have only a single keyboard and video display unit.
Midrange Systems Constitute the broadest category of computer systems, stretching all the way from microcomputers to the much larger mainframes and supercomputers.
Mainframe Computers The heart of the computing systems for many, perhaps most, major corporations and government agencies.
Supercomputers The high-end supercomputers are specifically designed to handle numerically intensive problems, most of which are generated by research scientist, such as chemists, physicists, and meteorologists. Thus, most of the high-end supercomputers are located in government research laboratories or on major university campuses.


Mainframe Computers
Mainframes are the heart of the computing systems for mostly major corporations and government agencies.The strength of mainframes is that they can handle : online and batch processing, standard business applications, engineering and scientific applications, network control, systems development, Web serving, and more. Because the importance of mainframes in corporate computing, a wide variety of applications and systems software has been developed for these machines.
The competition was fierce in the mainframe arena because of its central role in computing. The dominant vendor has been IBM since the late 1950s. The machines of IBM mainframe are built around the IBM multichip module (MCM) and quad-core processor chips. IBM has maintained its preeminent position in the mainframe arena through solid technical products, excellent and extensive software, extremely reliable machines, and unmatched service (Hamm, 2009b). Direct competition in the mainframe arena is less fierce than it used to be. Two vendors, Amdahl and Hitachi (Japan) dropped out of the mainframe market in 2000. The only remaining major players in the mainframe market are Fujitsu and Unisys. There is plenty of indirect competition in the mainframe arena, as vendors like Hawlett-Packard and Sun Microsystems try to get customers to migrate their mainframe systems to high-end servers.
The demand for mainframe computers goes up and down over time, varying with the price-performance ratios of mainframes versus servers, with the introduction cycle of new machines, and with the health of the economy. In recent years, IBM and other vendodrs have introduced new technology, addded Linux options to proprietary operating systems, and slashed prices drastically.The role of the mainframe will continue to evolve as we move further into the twenty-first century, with more emphasis on its roles as keeper of the corporate data warehouse, server in sophisticated client/server applications, consolidator of smaller servers, powerful Web server, and controller of worldwide corporate networks.
Supercomputers
The high-end supercomputers are specifically designed to handle numerically intensive problems, most of which are generated by research scientists (chemists, physicists, and meteorologists). Midrange supercomputers have found variety of uses in large business firms,most frequently for research and development efforts.
Until the mid- 1990s, the acknowledged leader in the high-end supercomputer arena was Cray Inc. In the November 2009 listings of the world's top 500 supercomputers, the top 100 machines were distributed as follows: IBM 33, Cray Inc. 14, Silicon Graphics International (SGI) 12, Hewlett-Packard and Sun Microsystems 8 each, and 10 other vendors with 4 machines or less, plus 3 other machines that were built by a combination of vendors (two of these including IBM) (Top 500, 2009). An interesting development in the supercomputer arena occured in 1996 when Silicon Graphics, Inc., acquired Cray Research, thus becoming the world's leading high-performance computing company.
KEY TYPES OF SOFTWARE
All computers use the stored-program concept; on all computers, a machine language program is loaded in memory and executed by the control unit. There are two major categories of software :
Application software
Support software
Application software includes all programs written to accomplish particular tasks for computer users. Appication programs include a payroll computation program, an inventory record-keeping program, a word processing product, a spreadsheet product, a program to allocate advertising expenditures, and a program producing a summarized report for top management.
Support software also called systems software does not directly produce output that users need. Support software provides a computing environment in which it is relatively easy and efficient for human to work. Support software is usually obtained from computer vendors and from software development companies.
APPLICATIONS SOFTWARE
Examples of applications software are portfolio management programs, general ledger accounting programs, sales forecasting programs, material requirements planning (MRP) programs, and desktop publishing products. Application software is sometimes developed within the organization and sometimes purchased from an outside source. The vast middle ground of applications include accounts payable, accounts receivable, general ledger, inventory control, sales analysis, and personnel reporting might be either purchased or developed. The rising costs of software development tend to be pushing the balance toward more purchased software and less in-house development. In an interesting development over the past two decades, much of the internal software development is now done by users who are not in the formally constituted IS organization.
An Example of An Application Product
There are many accounting products available for purchase as well as commercial products in a wide variety of categories to handle the accounting functions of a smaller business. The example product is Peachtree by Sage Premium Accounting 2010 with a retail price of $500 for a single-user version.This product has all the features that a small to midsized businesswould need, including general ledger, accounts receivable, acccount payable, inventory, payroll,time and billing, job costing, fixed asset accounting, and analysis and reporting tools.
Personal Productivity Software
Personal productivity software is the most important category of application software. These are the applications that staff and fellow managers will use on a reguler basis: word processing, spreadsheeets, presentation graphics, electronic mail, desktop publishing, microcomputer-based database management systems, Web browsers, statistical products, and other similar easy-to-use and extremely useful products. These products are microcomputer based, and they have been developed with a friendly, comfortable graphical user interface (GUI).
WORD PROCESSING
Word processing might be the most ubiquitous of the personal productivity software products. Today managers and professional workers alike create their own documents at a microcomputer keyboard. The first popular word-processing product was WordStar, which was in turn supplanted by WordPerfect in the 1980s and then by Microsoft Word in the 1990s.
SPREADSHEETS
Second only to word processing in popularity are electronic spreadsheets products, the most widely used of which is Microsoft Excel. The idea of spreadsheet is based on the accountant's spreadsheet, which is a large sheet of paper divided into many columns and rows on which the accountant can organize and present financial data. The spreadsheets approach can be used for any application that can fit into the rows and columns framework, including budget summaries for several time of periods, profit and loss statement for various divisions of a company, sales forecasts for the next 12 months, and so on.
DATABASE MANAGEMENT SYSTEM
The most widely used product is Microsoft Access, FileMaker Pro, Alpha Software's Alpha Five, and Corel Paradox. dBase was the desktop DBMS leader in the 1980s but has now disappeared. All these products are based on the relational data model.
PRESENTATION GRAPHICS
Used for creating largely textual presentations, but with embedded clip art, photographs, graphs, and other media, the leader in this field is Microsoft Power Point, followed by Corel Presentations, OpenOffice Impress,and Google Docs. For more complex business graphics, the leading products are Microsoft Visio, Adobe Illustrator, and CorelDRAW Graphics.
ELECTRONIC MAIL and GROUPWARE
Electronic mail has become the preferred way of communicatingfor managers in most businesses today. It is asynchronous and unonbtrusive, easy to use and precise. Groupware has the goal of helping a group become more productive and includes innovative ways of data sharing.
OFFICE SUITES
Office suites combine certain personal productivity software applications into integrated suites of applications for use in the office. The commercial office suites are Microsoft Office Suite, Corel WordPerfect Office, and SunStar Office.The office suite is an idea that is here to stay because of the ability to move data among the various products as needed.
WORLD WIDE WEB BROWSERS
A very important type of personal productivity software is the Web browser used by an individual to access information on the World Wide Web. The Web browser is the software that runs on the user's microcomputer, enabling the user to look around or "browse" the internet. Web browsers are based on the idea of pull technology. Push technology is also important. In push technology, data are sent to the client without the client requesting it.
OTHER PERSONAL PRODUCTIVITY PRODUCTS
There are many other personal productivity products such as :
Desktop publishing (Adobe InDesign, Microsoft Office Publisher, QuarkXPress, etc.)
Security products (Norton Internet Security and ZoneAlarm Extreme Security)
Project scheduling (Microsoft Office Project, Project KickStart Pro, and Tenrox Online Project Management.)
Image editing (Adobe Photoshop Elements, Corel Paint Shop Pro Photo, etc.)
Video editing (Adobe Premiere Elements, Corel Video Studio, etc.)
SUPPORT SOFTWARE
The Operating System
The operating system is a very complex program that controls the operation of the computer hardware and coordinates all the other software so as to get as much work done as possible with the available resources. Job Control Language (JCL) is an instrusctions expressed to start a program or retrieve a data file on larger machine. The operating system can create a computing environment in which it is realtively easy to work.
Advanced Operating System
Operating system incorporate two important concepts : multiprogramming and virtual memory, in order to increase the efficiencyof the computer's operations. Multiprogramming is often employed to switch among programs stored in memory in order to overlap input and output operations with prcessing time.
Multitasking is used to describe essentially the same function as multiprogramming on larger machines. Multithreading is almost the same as multitasking except that the multiple threads are different parts of the same programs that are being executed near simultaneously, with the operating system controllling the switching back and forth among threads of the single program.

Sources Of Operating System
For the most part, operating system are obtained from the manufacturer of the hardware, although some other company might have written the operating system. A server operating system, also called a network operating system (NOS) is software running on a server that manages network resources and controls the operation of network.
Language Transalators
Programs written in machine language do not have to be translated , they may be run directly on the compiuter model for which they were written. Written languageprograms are very tedious and demanding to write so computer developres created languages easier for humans to use as well as the associated languages translator programs to convert these easier-to-write programs to machine language.
Third Generation Language
The third and fourth generation languages represents a radical departure from the first two generation. Both machine language and assembly language programming require the programmer to think like the computerin terms of the individual instructions. Third generation language are also called procedural languages because they express a step-by-step procedure devised by the programmer to accomplish the desired task.
COBOL
COBOL, which is an acronym for COmmon Business-Oriented Language, as an example of a procedural language. Since its inception in 1960, COBOL has gained widespread acceptance because itis standardized has strong data management capabilities and is relatively easy to learn and use. COBOL is by far the most popular language for programming mainframe computers for business applications.
COBOL programs are divided into four distinct divisions. The fisrt two divisions are usually fairly short. The identification division gives the program a name, and the environment division describes the computer environmnet in which the program will be run.The data division which is often quite lengthy, defines the file structures employed in the program. The procedure division corresponds most closely to other procedural language programs; it consists of a series of operations specified in a logical order to accomplish the desired task.
OTHER PROCEDURAL LANGUAGES
We will mention only three of the more procedural languages in addition to COBOL :
Fortran It was introduced in the mid-1950s and quickly became the standart for scientific and engineering programming. Fortran is still widely used today, in good part because of the significant investment made in the development of Fortran scientific software.
Basic the simplest of the widely used procedural languages. Basic, which is an acronym for Beginner's Ail-purpose Symbolic Instruction Code, was developed in the early 1960s by John Kemeny and Thomas Kurtz at Dartmouth College. Their purpose was to create an easy to learn, interactive languages for College students that would let the students concentrate on the thought processes involved in programming rather than the syntax.
C which was written by Dennis Ritchie and Brian Kernighan in the 1970s, is a very important languages for scientific and engineering programming. C is a very powerful languages but hard to use because it is less English like and closer to assembly languages than the other procedural languages. C was originally developed for and implemented on the UNIX operating system, and its use grew as UNIX spread.
Fourth Generation Languages.
Fourth Generation Languages Fourth generation languages also called productivity languages and nonprocedural languages. The 4 GLs generally employ English-like syntax and—because they are predominantly nonprocedural in nature—the order in which instructions are given in a 4 GL is usually unimportant. In addition, 4 GLs do not require the user to manage memory locations in the program like 3 GLs, resulting in less complex programs. The 4 GLs employ very-high-level instructions not present in 3 GLs, and thus 4 GL programs tend to require significantly fewer instructions than their 3 GL counterparts. This in turn means that 4 GL programs are shorter, easier to write, easier to modify, easier to read and understand, and less error-prone than 3 GL programs. Fourth generation languages are sometimes called very-high-level languages in contrast to the high-level third generation languages. Some fourth generation languages use an interpreter to translate the source program into machine language, and some use a compiler. The fourth generation languages are evolving more rapidly than those in the third generation, particularly with the addition of easy-to-use business intelligence options and easy-to-interpret graphical output and colorful displays. However, the 4 GL label is disappearing in favor of the business intelligence (BI) tag. Furthermore, with the increasing capabilities of today's computers, the lack of efficiency of execution of 4 GL programs is of less concern.
BEYOND THE FOURTH GENERATION LANGUAGES
Markup languages comes after the 4 GLs. It is object-oriented programming languages, and languages for developing Web applications, and we will turn to these types of languages next. Another possibility is the development of natural languages, in which users write their programs in ordinary English (or something very close to it). Users will need little or no training to program using a natural language; they simply write (or perhaps verbalize) what they want done without regard for syntax or form.
Markup Languages
Before turning to object-oriented programming languages, we should mention the markup languages. Currently the best known of the markup languages is Hypertext Markup Language (HTML). HTML is used to create World Wide Web pages, and it consists of special codes inserted in the text to indicate headings, bold-faced text, italics, where images or photographs are to be placed, and links to other Web pages. eXtensible Markup Language (XML) is destined to become even more important than HTML. XML is used to facilitate data interchange among applications on the Web; it is really a metalanguage standard for specifying a document markup language based on plain-text tags. XML was developed by W3C, the World Wide Web Consortium, whose goal is to develop open standards for the Web. Entire sets of XML tags are being defined for particular industries and situations. The key is that XML is a metalanguage: For each industry or unique situation, a set of XML tags can be created to identify the data elements employed in that situation. XML makes it relatively easy to identify and share data in order to achieve data integration across organizational boundaries. XML is "extensible" in that new tags can be defined as needed, and XML allows the separation of the presentation of the data from the data themselves. Through the use of text tags, for example, a company can identify specific pieces of data on a Web page (such as a customer order) and can extract the desired data for use in another application. Thus, XML provides an easy and effective way to identify and share data.
Object-Oriented Programming
Object-Oriented Programming Object-oriented programming (OOP) languages are not new (dating back to the 1970s), but OOP has received renewed attention because of the increased power of workstations and the excellent GUIs that have been developed for these computers. OOP is neither a 3 GL nor a 4 GL but an entirely new paradigm for programming with roots in both the procedural 3 GLs and the nonprocedural 4 GLs. The fundamental ideas of OOP are to create and program various objects only once and then store them for reuse later in the current application or in other applications. These objects might be items used to create the user interface, like a text box or a check box, or they might represent an entity in the organization, such as Employee or Factory.
Languages for Developing Web Applications
Although Web-based applications range in complexity from very simple applications that allow user registration to applications that enable business-to-business transactions, they all have the following things in common:
All Web applications are based on an n-tier architecture (where ). The typical system consists of three tiers: a user interface (client), a Web or application server, and a database server.
The user interacts with the system (on his or her machine) through Web-based forms. Data entered into the forms are sent to the server, where a server application program processes them. This program might write parts of this information to a database (residing on a different machine). The most common user interface encountered by users is an HTML form.
DATABASE PROGRAMMING
Data processing activity with a database can be specified in either procedural programs written in a 3 GL or via special-purpose languages developed for database processing. With the commands available through the special enhancements to the language provided by the DBMS, only one instruction is needed in the program and all the associated indexes and records are updated automatically, which makes the programming task more productive and less error-prone. A DBMS also frequently provides a 4 GL, nonprocedural special-purpose language, called a query language, for posing queries to the database.
MANAGING THE DATA RESOURCE
Data are now recognized as a major organizational resource, to be managed like other assets such as land, labor, and capital. Another software tool for managing the data resource is a data dictionary/directory (DD/D), which is a repository of data definitions that is shared among all the users. Such a central catalog is used by the DBMS and system users whenever the meaning, storage format, integrity rules, security clearances, and physical location of data need to be discovered.
CASE Tools
Computer-aided software engineering (CASE) is actually a collection of software tools to help automate all phases of the software development life cycle. In those firms that have adopted CASE tools, CASE has radically changed the jobs of systems analysts and programmers. In particular, the job of the analyst or programmer involves more up-front work in clearly defining the problem and expressing it in the particular specifications required by the CASE tool. Then the tool assists in the back-end work of translating the specifications to the required output, such as a data flow diagram (see Chapter 8) or a COBOL program. There has been a recent surge in the use of CASE tools for object-oriented development based on the Unified Modeling Language (UML). UML is a generalpurpose notational language for specifying and visualizing complex software, especially large, object-oriented projects. For now, note that CASE is only beginning to make an impact. CASE has the potential of providing a productivity boost to an area of the company (the information systems organization) that needs such a boost.
Communications Interface Software
Communications interface software, our fifth type of support software, has become increasingly important with the explosion in the number of local area networks (LANs) and wide area networks (WANs) and with the growing importance of the Internet and the World Wide Web. The communications interface software on the server to "serve" the Web pages to the browser is called, appropriately enough, Web server software. Another valuable communications interface product is File Transfer Protocol (FTP). This product is designed to transfer files from one computer system to another. In effect, the user logs into the two computer systems at the same time and then copies files from one system to the other. The files being transferred might be programs, textual data, images, and so on.
Utility Programs
Our final type of support software is obviously a catch-all category, but an important one nevertheless. On large computers, utility software includes programs that load applications programs into an area of memory, link together related programs and subprograms, merge two files of data together, sort a file of data into a desired sequence (e.g., alphabetical order on a particular data item), and copy files from one place to another (e.g., from a DASD to magnetic tape). Utility programs also give the user access to the software library. In most cases, the user communicates with these utility programs by means of commands in the job control language. On a microcomputer, utility programs are used to zip (compact) and unzip large files for easier transport, to reorganize the hard drive to gain disk space, to check for computer viruses and spyware, and for many other tasks.
THE CHANGING NATURE OF SOFTWARE
We have noted many of the important trends in the software arena. Building upon our earlier discussions, we can explicitly identify six key trends that have the most direct relevance :
More concern with human efficiency. Software tools that improve human efficiency, such as objectoriented languages, query languages, and CASE tools.
More purchased applications, less purchased support software. The advantage to managers of the trend toward more purchased applications is that they will be able to get new applications implemented more quickly; the disadvantage is that the purchased software might not be able to do precisely what they want done in the way in which they want it done.
More programming using object-oriented languages. In part because of the emphasis on graphical user interfaces (GUIs), Visual Basic .NET, Java, and similar object-oriented programming languages will gain even more widespread acceptance.
More emphasis on applications that run on intranets and the Internet. More organizations are creating or buying applications that run on the Internet or their internal intranet (a network within an organization that uses the same technology as the Internet) because it is both easy and economical to make these applications available to everyone who needs them.
More user development. Managers and other professionals will carry out more software development efforts themselves
More use of personal productivity software. The use of personal productivity software will grow for managers and other professionals.

THE INFORMATION TECHNOLOGY INDUSTRY
Many hardware and software products, as well as many vendors, have been mentioned in this chapter, but we lack a frame of reference from which to view the IT industry. Let's start with the two largest players in the global IT industry: Hewlett-Packard (HP) and IBM. Both companies started primarily as hardware vendors, but both now have a major presence in the software and computer services arena. In the hardware arena, the other major players were mentioned earlier in this chapter: in the microcomputer segment, Dell, Acer (Taiwan), Lenovo (China), Apple, and the Japanese trio of Toshiba, Fujitsu, and Sony; in the midrange and larger segments, the same players plus Sun Microsystems.. In addition to the software sold by hardware vendors, there is an interesting and competitive group of software companies, although they are dominated by a single firm. Microsoft, the largest and most influential software house, is based in Redmond, Washington, and until 2000 was headed by Bill Gates, reportedly the richest person in the world. Other major software vendors include Oracle, which began by specializing in mainframe DBMSs but has now branched out into other areas In addition to these big software houses, there is a multitude of medium-sized to small-sized software firms. Many of the smaller firms tend to rise and fall rapidly based on the success or failure of a single product, and often the most promising of these small firms are purchased by the major vendors (Software Top 100, 2010). Most of the large software vendors have grown both by increased sales of products developed internally and by the purchase of other software firms, sometimes large firms.