High- and low-level languages and their translators

Question 1

What is a low-level programming language?

Answer 1

A programming language that is easier for the processor to interpret but harder for humans to understand.

Two low-level languages:

1. machine language/object code
2. assembly language

Question 2

What is machine language?

Answer 2

• lowest level of language
• consists of binary and/or hexadecimal
• raw instructions that the CPU carries out (processor reads machine code directly, no need to translate it)
• each CPU family has a different set of machine code

Question 3

What is assembly language?

Answer 3

• uses abbreviations or mnemonics for each operation code
• easier to read and write than machine language
• must be translated into machine code by an assembler before it can be run by a processor

Question 4

What is an assembler?

Answer 4

• translation program that translates processor-specific assembly code (source code) into machine code (object code) for a specific processor
• translates an entire program but does not run it
• it is rapid and reliable

Question 5

List some advantages of using low-level languages

Answer 5

• complete freedom of choice of instructions
• direct control over the processor’s communication with its input, output and storage devices
• efficient programs can be written that:
  
  • fir into limited storage space
  • require limited RAM
  • run rapidly

Question 6

List some disadvantages of using low-level languages

Answer 6

• lack of relation to a human language makes it difficult for programmers to read
• machine-oriented nature makes it hard for a programmer to learn, as each operation code must be memorised or looked up
• processor-specific nature of the instruction set means that programs are not transferrable or portable between families of processor
• programs are relatively hard to test, debug and maintain

Question 7

What is a high-level programming language?

Answer 7

A programming language that looks more similar to a human language or mathematical notation and is therefore easier for programmers to use. However, a program must be used to translate the language for the processor.

They are intended to help programmers solve problems rather than to micro-manage the computer’s hardware.

Question 8

What is a compiler?

Answer 8

• a program that translates all the high-level source code by compilation
• compilation must be completed before the program can be run, i.e. the entire program must be translated before the processor can execute the instructions
• if there are errors in the source code, the compiler produces an error report, the programmer corrects the errors and compiles the whole program again
  
  • therefore, the debugging of a large program before it can be run can be a slow, iterative process

Question 9

What is an interpreter?

Answer 9

• program that translates high-level language statements and executes them on a specific processor and operating system
• does not create machine code
• analyses one source code statement at a time and runs appropiate subroutines to execute it
• if the interpreter finds an error in the source code, it produces an error report and stops the execution
• the process of translation slow the execution, but debugging a large program is faster as the program does not need to be re-compiled after every edit

Question 10

List 5 differences between a compiler and an interpreter

Answer 10

• compiler produces object code; interpreter doesn’t produce object code
• compiler translates whole program in one go; interpreter translates and executes line at a time
• compiler produces list of all errors; interpreter produces error message each time an error is encountered
• compiler produces “stand alone code”; interpreter doesnt produce “stand alone code”
• compilation process is slow but resultant code runs very quickly; interpreted code runs slowly