1.2 Software and Software Development Flashcards Preview

Computer Science > 1.2 Software and Software Development > Flashcards

Flashcards in 1.2 Software and Software Development Deck (51):
1

What is the need, function and purpose of an operating system?

An operating system is the software that manages the computer;
- manages the hardware of the system
- manages the interface between the user and the computer
- manages the programs being run and installed
- manages the security of the system

2

What is paging?

x

3

What is segmentation?

?

4

What is the purpose of virtual memory?

x

5

What is the role of interrupts?

x

6

What is ISR?

x

7

Describe Round Robin

x

8

Describe first come first serve

x

9

Describe multi-level feedback queues

x

10

Describe shortest job first

x

11

Describe shortest remaining time

x

12

Describe and explain the purpose of a distributed os

Allows a group of computers to work on a single task. It can control and co-ordinate many computers, presenting them to the end user as though they were a single system

13

Describe and explain the purpose of an embedded os

Specifically designed for the device on which they run and with efficiency in mind. Operate on low-powered CPU's with little RAM. Will only likely to have one job

14

Describe and explain the purpose of a multi-tasking os

Organises the computer when it is running several applications at once.

15

Describe and explain the purpose of a multi-user os

Allows more than one user to share the computers resources at a time. Common on mainframe systems where there may be many users accessing them simultaneously

16

Describe and explain the purpose of a real time os

Designed to carry out actions in a guaranteed amount of time even when left running for long periods. i.e. hospitals and safety critical systems

17

Describe the purpose of the BIOS

Basic Input Output System - is what allows the computer to start up. Stores the load instructions

18

Describe the purpose of device drivers

A piece of software that is supplied with the device that allows the operating system to communicate with the device

19

What is the purpose of virtual machines?

Runs a simulation of an operating system on top of the current one, so that the user can test a program that may be used on multiple platforms. Often programs may not run on the provided operating system, so a virtual machine may be needed to run the desired program

20

What is the difference between utility and application software?

Application software allows the user to produce something or perform a task whereas utility software is usually a small program concerned with the maintenance of the system

21

What is the difference between open and closed source software?

x

22

What is an interpreter?

Converts high level language, translates and executes code line by line
+ can find the errors as they occur and give specific direction
+ same piece of code can work across different platforms
- lower performance
JavaScript uses an interpreter

23

What is a compiler?

Converts high level language, translates all the code into object code and then executable code
+ faster to convert
- keeps source code private
- can't use across different platforms

24

What is an assembler?

Converts low level language (assembly code) into machine code

25

State the stages of compilation

Lexical Analysis
Syntax/Semantic Analysis
Code Generation
Code Optimisation

26

What is a linker?

The job of the linker is to include links to any library code required by the object code and put this into one executable file

27

What is a loader?

The loader is responsible for loading the correct files and libraries into the computer memory when the program is run

28

Describe and evaluate the waterfall life cycle

x

29

Describe and evaluate agile methodologies

x

30

Describe and evaluate the purpose of extreme programming

x

31

Describe and evaluate the spiral model

x

32

Describe and evaluate rapid application development

x

33

OOP terms

x

34

Evaluate high level code

+ easier to code
+ more understandable
+ can code more complicated programs
- lose control over the instructions being executed

35

Evaluate low level code

+ faster to compile
+ more control over the CPU and the instructions executed
- will only work on the CPU with the instructions referenced

36

Describe lexical analysis

Breaks the code down into a series of tokens by; removing white space and comments, remaining code turned into tokens, symbol table is created to keep track of variables and subroutines

37

Describe syntax/semantic analysis

If any tokens break the rules of the language, errors are generated at this point
Abstract syntax tree is built from tokens produced in previous stage

38

Describe code generation

Object code is the machine code before the final step (the linker) is run. Abstract code tree converted into object code

39

Describe code optimisation

Tweaks the code so that it will run as quickly as possible and use as little memory as possible

40

Explain static linking

The code needed to form the libraries is copied and included in the executable file. The code doesn't need to access external libraries during run time, therefore if a library is missing the program will not crash
- can take a long time
- large file size, takes up more space in RAM

41

Explain dynamic linking

Compiled versions of the libraries are stored in the computer and linked with the object code by the OS at run time
+ less memory is needed therefore quicker to process
+ less code needed to compile
- if a library is missing the program will crash

42

What is a library?

Pre-written modules of code for the user to interact with.

43

What is a paradigm?

Different forms of programming languages; low level, high level, imperative, procedural, OOP

44

What is imperative programming?

Mainly used within assembly code. It is a sequence of instructions where subroutines are not used. The program is directed around the code using GOTO statements and branches

45

What is procedural programming?

A sequence of instructions however the code is split into subroutines and the sequence of code is based on these i.e. IF WHILE FOR

46

What is OOP code?

For use in large software projects where code needs to be repeated. Way of inheriting and creating classes

47

What are the 4 addressing modes?

Immediate
Direct
Indirect
Indexed

48

Describe and evaluate intermediate addressing

Addressed from the binary operand value. The operand is not a memory address but the value to be used
+ fastest method as you do not need to access the computers memory

49

Describe and evaluate direct addressing

References the address that the data is stored in
+ quick method however not as quick as intermediate
- relies on the value always being correct at the location specified

50

Describe and evaluate indirect addressing

References a place in memory which then points to the data
- address of where the data is stored must first be looked up

51

Describe and evaluate indexed addressing

Start number then add the address to find the address of where the data is stored
- slower than previous methods but more flexible when loading larger amounts of data
+ good for data structures which require large blocks of data