Computer Systems - Programming Languages

What is machine code?

A programming language that uses binary patterns of 0s and 1s which can be executed by a computer directly

Why is machine code machine-dependent?

It is based on the computer's instruction set (which is machine-dependent)

What is assembly language?

A programming language that uses mnemonics

Why is assembly language machine-dependent?

It has a one-to-one relationship with machine code (which is machine-dependent)

Which programming languages are low-level and why?

Machine code and assembly language as their code reflects how the hardware actually carries out the instruction and they're both based on the instruction set of the computer

What are high-level programming languages?

Programming languages that are English-like and machine-independent

What are imperative programming languages?

High-level languages where commands are given and then executed one-by-one to solve a problem or accomplish a task

What are the advantages of low-level languages over high-level languages?

-Can be more control over hardware (registers)

-Can be more memory efficient

-Can write more efficient, faster programs

What are the advantages of high-level languages over low-level languages?

-Machine independent

-Easier to understand

-Easier to debug - less error-prone

-Shorter, less lines of code - quicker to code

-Data structures, subroutines

-Indentation, whitespace and constants

Why must high-level languages and assembly language be converted into machine code?

The processor can only understand and execute machine code

What is source code?

Code written by a programmer in high-level or assembly language

What is object code?

The resulting, executable code of a compiler (normally in machine code)

What is an assembler?

A translator that converts assembly language into machine code

What is a compiler?

A translator that converts an entire high-level program into an object code executable (in machine code)

What is an interpreter?

A translator that executes high-level code line-by-line by calling an appropriate subroutine for each statement

What are the advantages of compilers over interpreters?

-Source code unneeded after compilation (more secure)

-Compiled programs don't normally need to be recompiled (doesn't need the compiler) but an interpreter needs to translate the code each time the program is run (interpreter is needed every time)

-Resultant object code executes faster than an interpreted program

What are the advantages of interpreters over compilers?

-To test small sections of code, no need for compilation

-No need for recompilation if there's an error

-Can run syntactically correct parts of a program while there are syntax errors elsewhere in the code

-Stops at the location of an error - easier to debug

-Program code can be interpreted on any computer (important for programs like websites)

What are compiled programs suitable for?

Programs that are frequently used or distributed

What are interpreted programs suitable for?

Websites, program testing or teaching code

What is bytecode?

An intermediate language that is the result of some compilers and is executed by an interpreter on a virtual machine

Why is bytecode machine-independent?

It can be interpreted on any computer with the correct virtual machine