Programming languages

Question 1

Describe what is meant by a ‘low-level language’ using examples.

Answer 1

Machine code and assembly language are low-level languages that work directly with a computer’s hardware

Question 2

What is machine code?

Answer 2

• Written in binary, made up of thousands of 1s and 0s
• This makes it very difficult for programmers to write and debug

Question 3

What is assembly language?

Answer 3

• Only a bit easier to work with
• Uses mnemonics to represent instructions

Question 4

Give some advantages and disadvantages of using low-level languages.

Answer 4

Advantages:

• Interact directly with the hardware, enabling memory to be used efficiently - allows for faster execution of a program

Disadvantages:

• Difficult and time-consuming to use
• Have few tools that help with debugging and maintenance
• They are machine-specific

Question 5

Describe what is meant by a ‘high-level language’ using examples.

Answer 5

High-level languages, such as Java and Python, are programming languages closer to human languages than low-level languages

(use keywords like ‘print’, ‘if’ and ‘return’)

Question 6

Describe some features of high-level languages.

Answer 6

• They are problem-oriented - enable programmers to focus on a program’s logic, rather than on how it will be implemented on a computer’s hardware
• Come with libraries of ready-made functions and editing tools to make it easier to write code

Question 7

Give some advantages and disadvantages of using high-level languages.

Answer 7

Advantages:

• Programmer-friendly
• Have tools that help with debugging and maintenance
• They are machine-dependent (portable) - will run on computers with different types of CPU

Disadvantages:

• Generally less memory efficient

Question 8

(Exam-style question)

A program written in a high-level language will run on computers with different types of CPU, whereas one written in a low-level language is machine-specific.

Explain this difference. (3)

Answer 8

• Programs written in a high-level language focus on the program logic and do not concern themselves with how it will be implemented on particular computer architecture
• Programs written in a low-level language use the instruction set of a specific CPU

Question 9

(Exam-style question)

A program is needed to control an embedded system with very limited on-chip memory.

Explain one reason why a programmer may decide to write the program in a low-level language. (2)

Answer 9

• Using a low-level language ensures that the system’s memory is used efficiently
• This is because it enables the programmer to select the most appropriate instructions to use and to directly control the hardware to be used

Question 10

What is the condition for programs to be executed by the CPU?

Answer 10

Programs have to be translated into machine code before they can be executed by the CPU

Question 11

(Exam-style question)

Explain one reason why program code developed using a high-level language must be translated. (2)

Answer 11

Instructions must be translated into machine code because that is the only language the CPU can execute

Question 12

Give three examples of translators.

Answer 12

• Compiler
• Interpreter
• Assembler

Question 13

State the purpose of a compiler.

Answer 13

To translate a high-level language’s source code into machine code (object code)

Question 14

State the purpose of an interpreter.

Answer 14

To translate high-level code line by line into machine code

Question 15

State the purpose of an assembler.

Answer 15

To translate assembly language into machine code

Question 16

Give some advantages of using a compiler to translate a programming language.

Answer 16

• Translates all program code into machine code at same time
• Program only has to be translated once - allows for faster execution of program
• Protects software from competitors as source code is not available to them

Question 17

Give some disadvantages of using a compiler to translate a programming language.

Answer 17

• Reports list of errors after having compiled whole program if it encounters any, making debugging harder
• You cannot change the program without going back to, editing and recompiling the original source code
• Compiled programs can only be ran on specific systems

Question 18

Give some advantages of using an interpreter to translate a programming language.

Answer 18

• Stops translating program when an error is found and reports it - lets programmer know where it occurred, making debugging easier
• Program code can run on any system that has the interpreter
• Program can be easily edited as it always exists as source code

Question 19

Give some disadvantages of using an interpreter to translate a programming language.

Answer 19

• Each line of code has to be translated every time program is executed, therefore it is slower to run