Chapter 01 Checkpoints

Question 1

1.1 Why is the computer used by so many different people, in so many different professions?

Answer 1

1.1 Because the computer can be programmed to do so many different tasks.

Question 2

1.2 List the five major hardware components of a computer system.

Answer 2

1.2 The Central Processing Unit (CPU), main memory, secondary storage devices, input devices, output devices.

Question 3

1.3 Internally, the CPU consists of what two units?

Answer 3

1.3 Arithmetic and Logic Unit (ALU), and Control Unit

Question 4

1.4 Describe the steps in the fetch/decode/execute cycle.

Answer 4

1.4 Fetch: The CPU’s control unit fetches the program’s next instruction from main memory. Decode: The control unit decodes the instruction, which is encoded in the form of a number. An electrical signal is generated. Execute: The signal is routed to the appropriate component of the computer, which causes a device to perform an operation.

Question 5

1.5 What is a memory address? What is its purpose?

Answer 5

1.5 A unique number assigned to each section of memory.

Question 6

1.6 Explain why computers have both main memory and secondary storage.

Answer 6

1.6 Program instructions and data are stored in main memory while the program is operating. Main memory is volatile, and loses its contents when power is removed from the computer. Secondary storage holds data for long periods of time?even when there is no power to the computer.

Question 7

1.7 What are the two general categories of software?

Answer 7

1.7 Operating Systems and Application Software

Question 8

1.8 What fundamental set of programs control the internal operations of the computer’s hardware?

Answer 8

1.8 The operating system

Question 9

1.9 What do you call a program that performs a specialized task, such as a virus scanner, a de-compression program, or a data-backup program?

Answer 9

1.9 A utility program

Question 10

1.10 Word processing programs, spreadsheet programs, e-mail programs, Web browsers, and game programs belong to what category of software?

Answer 10

1.10 application software

Question 11

1.11 What is an algorithm?

Answer 11

1.11 A set of well-defined steps for performing a task or solving a problem.

Question 12

1.12 Why were computer programming languages invented?

Answer 12

1.12 To ease the task of programming. Programs may be written in a programming language, and then converted to machine language.

Question 13

1.13 What is the difference between a high-level language and a low-level language?

Answer 13

1.13 A low-level language is close to the level of the computer, and resembles the system?s numeric machine language. A high-level language is closer to the level of human readability, and resemble natural languages.

Question 14

1.14 What does portability mean?

Answer 14

1.14 That a program may be written on one type of computer and run on another type.

Question 15

1.15 Explain the operations carried out by the preprocessor, compiler, and linker.

Answer 15

1.15 The preprocessor reads the source file searching for commands that begin with the # symbol. These are commands that cause the preprocessor to modify the source file in some way. The compiler translates each source code instruction into the appropriate machine language instruction, and creates an object file. The linker combines the object file with necessary library routines.

Question 16

1.16 Explain what is stored in a source file, an object file, and an executable file.

Answer 16

1.16 Source file: contains program statements written by the programmer. Object file: machine language instructions, generated by the compiler translated from the source file. Executable file: code ready to run on the computer. Includes the machine language from an object file, and the necessary code from library routines.

Question 17

1.17 What is an integrated development environment?

Answer 17

1.17 A programming environment that includes a text editor, compiler, debugger, and other utilities, integrated into one package.

Question 18

1.18 Describe the difference between a key word and a programmer-defined identifier.

Answer 18

1.18 A key word has a special purpose, and is defined as part of a programming language. A programmer-defined identifier is a word or name defined by the programmer.

Question 19

1.19 Describe the difference between operators and punctuation symbols.

Answer 19

1.19 Operators perform operations on one or more operands. Punctuation symbols mark the beginning or ending of a statement, or separates items in a list.

Question 20

1.20 Describe the difference between a program line and a statement.

Answer 20

1.20 A line is a single line as it appears in the body of a program. A statement is a complete instruction that causes the computer to perform an action.

Question 21

1.21 Why are variables called variable ?

Answer 21

1.21 Because their contents may be changed.

Question 22

1.22 What happens to a variable s current contents when a new value is stored there?

Answer 22

1.22 The original value is overwritten.

Question 23

1.23 What must take place in a program before a variable is used?

Answer 23

1.23 The variable must be defined.

Question 24

1.24 What are the three primary activities of a program?

Answer 24

1.24 Input, processing, and output.

Question 25

1.25 What four items should you identify when defining what a program is to do?

Answer 25

1.25 The program?s purpose, information to be input, the processing to take place, and the desired output.

Question 26

1.26 What does it mean to visualize a program running ? What is the value of such an activity?

Answer 26

1.26 To imagine what the computer screen looks like while the program is running. This helps define input and output.

Question 27

1.27 What is a hierarchy chart?

Answer 27

1.27 A chart that depicts each logical step of the program in a hierarchical fashion.

Question 28

1.28 Describe the process of desk-checking.

Answer 28

1.28 The programmer steps through each statement in the program from beginning to end. The contents of variables are recorded, and screen output is sketched.

Question 29

1.29 Describe what a compiler does with a program s source code.

Answer 29

1.29 It translates each source code statement into the appropriate machine language statement.

Question 30

1.30 What is a run-time error?

Answer 30

1.30 A logical error that occurs while the program is running.

Question 31

1.31 Is a syntax error (such as misspelling a key word) found by the compiler or when the program is running?

Answer 31

1.31 By the compiler

Question 32

1.32 What is the purpose of testing a program with sample data or input?

Answer 32

1.32 To determine if a logical error is present in the program.

Question 33

1.33 Briefly describe the difference between procedural and object-oriented programming.

Answer 33

1.33 Procedural programs are made of procedures, or functions. Object-oriented programs are centered on objects, which contain both data and the procedures that operate on the data.