study notes yesterday

COMPUTER PROBLEM SOLVING AS A TOOL
1. The basics of computer processing
1.1. Computer architecture
Until now the computer has changed from the initial model, although all computers have the same basic architecture. Scheme computers (computer schema), is a diagram illustrating the basic units included in all computer systems.
Figure 1. computer scheme
1. Central processing unit (CPU), which controls all other units and computer systems that transform inputs into outputs.
• Primary storage (primary storage), containing the data being processed and the program.
• Control unit (control unit), make all units work together as a system
• Arithmatika and logical unit, where berlangsungkan mathematical calculations and logic operations.
2. Input Unit, entering data into the primary storage.
3. Secondary storage (secondary storage), menyedikan place to store programs and data when the sodium absorption ratio is used.
4. Output Unit, noted the results of processing.
1.1.1 Input Device
Some input devices have a dual function, namely as a means of input and output as well as a tool to generate the data. Instrument inputs / outputs so recognized by the terminal. Input devices are divided into two groups, namely the input devices directly and indirectly. When the terminal is connected to a computer center that is located far from the terminal via a communication tool, it is called by the name of the Remote Job Entry (RJE) terminals or remote batch terminals.
The tool allows direct input directly input processed by the CPU through the input device without first dinmasukkan into the external storage medium. Direct input tool consists of several groups, namely: keyboards, pointing devices, scanners, voice recognizer.
Indirect input devices, where the data entered is not directly processed by the CPU, but recorded prior to a media mechine readable form (a form that can only be read by a computer and an external storage). Indirect input devices consist of: key-to-card, key-to-tape, key-to-disk.
1.1.2. Primary storage (primary storage)
Primary storage exists in several forms that provide a variety of capabilities in terms of operation and speed. The size of primary storage is shown in units of Kilo Byte (KB), Mega Byte (MB), Giga Byte (GB). Forms of primary storage:
o RAM (random access memory), is accessible memory is memory that can be charged and taken its contents. RAM is volatile because its contents will be lost says power outages.
o ROM (read only memory) is memory that can be read only and non-volatile nature of the contents of the ROM will not be lost if the power goes out. ROM contains instructions and data that tells the computer what to do when the computer starts up.
o Cache Memory is a special RAM that is placed between the processor. Cache memory will be read first by the processor before seeking instructions or data at regular RAM.
1.1.3. Unit Output
The resulting output data processing can be classified into four forms, namely: text, image, sound, and forms that can only be read and understood computers. The first three are outputs that can be used directly by humans, while the fourth is used as input for further processing or as input to another computer.
Tool output may take the form:
1. Hard copy, a tool used for printing text, numbers, special characters and symbols as well as the image on hard media (hard) such as paper or film. Eg Printer, Plotter, COM (Computer Output Microform)
2. Soft copy, a tool used to display text, image on soft media (software) in the form of electronic signals. For example a video display, flannel flat displays, speakers.
1.2. Software
Software (software) is one or a collection of some programs. The software is divided into system software and application software.
Software systems perform basic tasks required of all users of computer-related hardware. This software is provided by the hardware manufacturer or by a company that specializes in making software. There are three basic types of system software: operating systems, language translators and utility programs.
The software application is a program created by the user using a programming language to accomplish a specific task.
1.2.1. Operating System (Operating System)
Operating system commonly known by the acronym OS is a program that has a function as an interface / liaison between users with software and hardware. OS just like managers in the company, which is responsible for, controlling and coordinating the activities of the computer system.
The main functions of Operating Systems
1. Management process, including preparation, scheduling, and monitoring process on the computer.
2. Resource management, relating to the control of resource use in a computer system by the system program or application program at the time.
3. Data management, control of data input / output, including in terms of allocation in the secondary storage device or in main memory.
The main purpose Operating System
1. Facilitate the use of computer systems mainly programmers.
2. Provide services for application programs to utilize computer resources.
3. Arranged for the computer system resources are used efficiently.
Example OS: DOS, Windows 95, Windows 98, Windows Me / Windows XP
Windows NT / Windows 2000, OS / 2, Unix, Linux
1.2.2. Software Applications (PLA)
This software helps the management of physical and conceptual resources of the company. PLA obtained in 2 ways:
1. Make your own (custom programming)
Some large companies are using computer aided information specialist staff, designing computer-based systems to meet the unique needs of companies. Their product is a collection of software (software library) from the program order (custom program).
2. Buying so (preweritten package).
Some application programs so that there is a market can be grouped into four groups:
1. General Business Application Package
2. Special Application Package industry
3. Increased Productivity Organization Application Package
4. Individual Productivity Package
1.3. The role of input devices, output and software in solving problems.
All input and output devices can contribute to solving the problem both directly and indirectly. Example: keyboards, displays, printers and plotters (direct role), source data automation devices, microfilm (indirect role).
Like the hardware, the software can also contribute directly or indirectly. Example: the operating system (indirect role), general business applications and industry (indirect role), some software applications increase in individual organizational productivity (indirect role), spreadsheets, statistical analysis and estimation, project management (direct role).
2. Database
2.1. Data Hierarchy
The company is taradisional organize their data in a hierarchy that consists of data elements (fields), notes (records), and files.
o Data elements, is the smallest unit, can no longer be divided into smaller units. Such as name, employee number, salary, hourly wage, etc..
o Note, consisting of data elements associated with an object or a particular activity, for example, notes that explain each type of inventory and each sale.
o File is a collection of records relating to a particular subject. Eg purchase order file, data file employee, the sales file.
2.2. Secondary storage (secondary storage)
Secondary storage is divided based on its data access
1. Sequential access storage device (SASD)
Tool storage with the preparation and reading of data sequentially ie one note follows another record.
2. Direct access storage device (DASD)
Tool storage with the preparation and reading of data directly into position.
2.3. Data processing (data processing)
There are two ways of data processing:
1. Clustered data processing (batch processing) processing is done by collecting transaction within a certain period
2. Direct data processing (online processing)
data processing done per transaction, sometimes when the transaction occurs. Real Time System: The system that controls the physical and requires a computer system to respond quickly to the status of a physical system
2.4. Database
2.4.1. Era Database
Before the era of the database is marked with
o Source of the data collected in the files that are not connected to each other
o Each application has the / designing your own data files
o It has a weakness: the duplication of data, data dependence, data ownership is spread
To solve the above problem is done by physically organizing the data and leads to the logical organization. Physical organization (logical organization), integrates data from several different physical locations and is the way users see the data. Physical organization (physical organization), is the way the computer sees the data as separate files.
Two techniques to meet the needs of logical integration:
1. Logical integration in a single file
o Inverted file
A file saved in a particular order, with an accompanying index allows the records of the selected file in a different order.
o Linked list
A technique that can achieve similar results without using the index but by determining its own field that are added to each record in the file.
2. Logical integration among multiple files
Using links to connect the records in a file with records that are logically related to another difile.
2.4.2. The concept of a database
Is a logical integration of records in many files. The database is an integrated collection of computer data, organized and stored in a manner that facilitates retrieval. Figure 2.
The main purpose of the database concept:
1. Minimize repetition of data
2. Data independence
3. Inconsistency of data
4. Sharing
Hierarchy of data:
o field
o record
o file
o databases
2.4.3. Database structure
The emphasis on data processing activities is the ability to access data quickly and efficiently in the use of secondary storage.
1. Multilevel data structure (hierarchical data structure)
The relationship between the data form a ladder like a tree. A tree is formed from several elements of a tiered data groups, called nodes. The topmost node or Level 1 is called the root. each node can be branched out to other nodes. One node has only one parent.
Figure 2. database consists of several files
2. The structure of the network data (network data structure)
Relationship with a hierarchical structure of data, but for every node can have more than one parent.
3. Data structure relationships (relational data structure)
Data compiled in the form of two-dimensional tables consisting of columns (fields) and rows (records). The relationship between the records based on the value of key field rather than by address or pointer in the record as in strutur trees and networks.
2.4.4. Database Management System (DBMS)
Is the software that establishes and maintains a logical integration between files, either explicitly or inplisit. Example: IDS, Information Management System (IMS), Structured Query Language / Data System (SQL / DS), Query by Example (QBE), ORACLE, dBase II-III-IV-III plus, Foxbase, Qbase etc..
2.4.5. Strengths and weaknesses of database and DBMS
Advantages:
1. reduce data kerangkapan
2. achieve data independence
3. integrate data from multiple files
4. retrieve data and information quickly
5. improve data security
Weaknesses:
1. expensive software
2. large hardware configuration
3. Database Administrator retain staff
2.4.6. The role of databases and DBMS in solving problems
Computerized database and the DBMS is not an absolute prerequisite for solving the problem. However, the basics of computer use as an information systems specialists and users of information.
2.5. File Organization
Is a technique or means by which states and store the records in a file.
There are four basic techniques of file organization, namely:
1. Sequential
2. Relative
3. Indexed Sequential
4. Multi - Key
In general, these four basic techniques differ in the way of accessing, namely:
1. Direct Access
2. Sequential Access
1. Direct Access;
Is a way of accessing the record directly, without accessing all existing records.
Example: Magnetic Disk.
2. Sequential Access;
Is a way of accessing the records, which preceded accessing the records in front of him.
Example: Magnetic Tape.
File Index
o It is a file that has an index or table that contains a list of addresses (add in Control Index.
o Control Index serves as a pointer / pointer from the position of a particular record is to go to a site specific records quickly.
o There shall be two files: data files and key files containing control  index.
o In order to be able to relate 2nya used a key field / key field
Factors that influence the selection process file organization:
• Characteristics of storage media used
• Volume and frequency of transactions processed
• Respontime required
Reading List
1. Abdul Kadir, Introduction to Information Systems, Andi Jogyakarta, 2003, Chapter 1, Chapter 3, Chapter 4
2. E.S Margianti, D. Suryadi HS, Management Information Systems, Gunadarma, 1994, Chapter 5, Chapter 6
3. Jogiyanto, Introduction to Computers, Andi Jogyakarta, 1999, Chapter 21
4. McLeod, Management Information Systems, Prentice-Hall, 1998, chapter 8,9,10