Unit 5

1. Unit 5 Information System Concepts

2. Unit 5: Information System Concepts 3 hours • List and briefly describe the phases in the system development cycle. • Define the term bit and describe how a series of bits represents data. • Differentiate between data and information. • Differentiate between online vs. offline processing, and batch vs. transaction processing.

3. List and briefly describe the phases in the system development cycle: 1. Planning 2. Analysis 3. Design 4. Implementation 5. Operation, Support, and Security

4. Binary Digit: • A binary digit (‘bit’ for short) is the smallest unit of representation within a computer system and can either be a zero or one (0 or 1). • A combination of binary digits for a byte. A byte is also called a character. This means a byte can be the letter ‘A’, or the digit ‘7’ or the symbol ‘$’.

5. Base 2 (Binary) • Because computers only use 0 or 1 to represent data, everything is done in this two state or base 2. We use the decimal system (base 10) which uses the digits between 0 and 9. It is the job of the computer to convert between the base 2 and the base 10 everything time we attempt to communicate with the computer.

6. Binary continued • This is why we use a character set (e.g. ASCII). ASCII (as discussed in another chapter) is a set of binary numbers that represent 256 characters (or 28 in binary). Therefore, each key that we touch (e.g. the letter ‘A’), has a numeric equivalent (e.g. 65) which is then converted into a binary number (e.g. 10000012).

7. Data and Information: • Data are raw facts which have not yet been processed. • Information is data which has been processed into a meaningful form.

8. Online vs. Off-line Processing • Online processing is a method of collecting and processing data in which transactions are entered directly into the computer system and processed immediately. • Offline processing is an processing which takes place independently of the central processing unit.

9. Batch vs. Transaction Processing • Batch processing is a method of collecting and processing data in which transactions are accumulated and stored until a specified time when it is convenient or necessary to process them as a group. • Transaction processing is information processing that is divided into individual, indivisible operations, called transactions. Each transaction must succeed or fail as a complete unit; it cannot remain in an intermediate state. 

10. What is data processing? • Computer data processing is any process that a computer program does to enter data and summarize, analyze or otherwise convert data into usable information. The process may be automated and run on a computer. It involves recording, analyzing, sorting, summarizing, calculating, disseminating and storing data. Because data are most useful when well-presented and actually informative, data-processing systems are often referred to as information systems. Nevertheless, the terms are roughly synonymous, performing similar conversions; data-processing systems typically manipulate raw data into information, and likewise information systems typically take raw data as input to produce information as output.