4.6 Fundamentals of computer systems

Question 1

What is a computer?

Answer 1

A machine that processes data by following instructions

Question 2

What is application software?

Answer 2

Application software is designed to perform tasks that a user wants to complete, such as playing a game, writing a letter, or sending an email.

Question 3

What is system software?

Answer 3

System software controls the hardware of a computer system.

Question 4

What is a library?

Answer 4

A collection of prewritten instructions that can be repurposed for use in other programs

Question 5

Describe at least 3 roles of an operating system

Answer 5

Hiding the complexity of hardware from the user
Provides a platform for applications for run on
User Interfaces
Processor scheduling — determining the order in which processes will be executed, which allows for multi-tasking
Handling interrupts — dealing with requests that disrupt the processor’s work
Memory management — recording how memory in the computer is divided and identified so that memory is allocated efficiently between processes that are running
Secondary storage management — tracking where files and programs are stored and which parts are available for storage, and managing files and folders based on user permissions
Input/output device management — ensuring efficient communication with devices and managing functionality issues

Question 6

What is a low-level language?

Answer 6

Low-level languages use the specific instruction set of a processor.

Question 7

What is machine code?

Answer 7

Binary instructions written directly to the processor (the only language that can do so)

Question 8

What does each low-level instruction consist of?

Answer 8

Each low-level instruction consists of two parts: an opcode and an operand.

OPCODE,OPERAND
eg.
001100 0010110100

Question 9

What is an opcode?

Answer 9

An opcode is the part of the instruction that specifies which operation the processor should perform.

Question 10

What is an operand?

Answer 10

The operand contains a value, or set of values, relevant to the opcode. The operand can be an actual piece of data, or it can be a reference to the memory location of the data for the opcode to act on.

Question 11

What is the addressing mode?

Answer 11

The addressing mode specifies the way in which the operand will be interpreted

Question 12

What does the opcode consist of?to

Answer 12

The opcode consists of the instruction to perform and the addressing mode.

Question 13

How do you work out the number of addressing modes from the bits allocated ?

Answer 13

2^bits allocated

eg. 2 bits, 2^2 = 4

Question 14

What is an assembly language?

Answer 14

A language that uses mnemonics that represent the binary equivalent machine code

Question 15

What is a high-level language?

Answer 15

High-level languages use command words and Syntax that reflect everyday language. They are designed to allow humans to interact with a computer system with no technical knowledge of the hardware.

Question 16

What is an imperative language?

Answer 16

Language/Paradigm where programmers solve a problem by writing a set of instructions that state how a problem should be solved.

Question 17

What is procedural programming?

Answer 17

Paradigm where the program can be split into procedures (or subroutines).

Question 18

What is a declarative language?

Answer 18

Declarative languages define what should be achieved by the program, not how to solve it.

Using a declarative language, the programmer specifies (or “declares”) the problem to be solved, without having to know how the solution is actually executed.

Question 19

What is an object oriented language?

Answer 19

A language that uses classes to define objects in order to model the problem to be solved.

Question 20

How does a compiler work?

Answer 20

Compilers translate code into a form that can be executed. The output from a compiler is an executable file .

Question 21

How does an interpreter work?

Answer 21

Interpreters translate and execute each line of source code one by one.

Question 22

Interpreter Vs. Compiler

Answer 22

Compiler pros:
Faster running time as no translation is required at run time.
The executable code cannot be reverse engineered back to its source code so is secure.
Compiler cons:
If you want to change something in the program you have to recompile it into a new file.
You only receive the errors in the code after the whole program is compiled.
Interpreter pros:
Translates line by line so errors are reported straight away. They are easier to find and fix making it better for debugging.
Interpreter cons:
Slower running time.
Interpreter must be downloaded o every machine code will run on taking up space in memory.