3.7 High- & Low-level Languages

Question 1

Instruction set

Answer 1

A set of binary numbers that match every instruction that can be understood by the CPU
*different computers may have different instruction sets

Question 2

Machine code

Answer 2

(The general term for) the number code that matches numbers to instructions / binary instructions that a computer understands

Question 3

Low-level language

Answer 3

LLLs relate to the specific architecture and hardware of a particular type of computer.
eg. machine code, assembly language

Question 4

4 advantages of low-level languages

Answer 4

1. Works directly on registers/CPU; code can be executed faster
2. Programmer has more control over what happens in computer
3. Can use machine specific functions
4. Code takes up less storage / memory efficient

Question 5

4 disadvantages of low-level languages

Answer 5

1. Difficult to read, write and understand
2. Easier to make mistakes
3. Time-consuming to write programs
4. Programs written in LLL may not work on other makes of computer

Question 6

Assembly language is often used to create device drivers for new types of hardware. What are device drivers?

Answer 6

Device drivers are instructions that let the CPU communicate with peripherals

Question 7

High-level language

Answer 7

• Closer to human language / English
• Independent of a particular type of computer // portable language
• A language such as Python, Java, Pascal

Question 8

3 advantages of high-level languages

Answer 8

1. Close to human language
2. Easier/faster to read and write
3. Portable code - programs written in HLL can be run on any computer once they have been translated into that computer’s machine code

Question 9

3 disadvantages of high-level languages

Answer 9

1. Take additional time to translate program to machine code
2. Generally less memory efficient, compared to LLLs
3. Programs are slower than low-level language programs

Question 10

Translators - Assembler

Answer 10

A program that translates a program written in assembly language into machine code.

• An executable file of machine code is produced, so assembled programs can be used without the assembler
• executable file creates a smaller file size, so more saleable
• An assembled program is usually distributed (sold/shared) for general use

Question 11

Translators - Compiler

Answer 11

A program that translates the whole high-level language program into machine code at once.

• An executable file of machine code is produced, so compiled programs are used without the compiler (it will be quicker to run)
• executable file creates a smaller file size, so more saleable
• A report/list of errors in the code is created
• A compiled program is distributed (sold/shared) for general use
• However, if you make a change the program must be compiled again
• Source code cannot be accessed, so code cannot be stolen/plagiarised

Question 12

Translators - Interpreter

Answer 12

A program that translates a high-level language program a statement at a time, and the machine code is directly executed.

• Will identify an error as soon as it finds one in a line of code
• No executable file of machine code is produced, so interpreted programs cannot be used without the interpreter
• However, if you make a change you can test the effect immediately, so an interpreter is often used when a program is being developed

Question 13

2 types of error

Answer 13

1. Syntax error - where a program statement doesn’t obey the rules of the programming language
2. Logic error - where the program doesn’t do what the programmer wanted it to do

Question 14

Why is a compiler or an interpreter needed when running a high-level program on a computer?

Answer 14

1. Code is required to be converted into machine code/binary

2. Code needs to be produced that can be understood by the computer