Computer Systems Nat 4/5 Computing Science Translator Programs

Computer Computer SystemsSystems

Nat 4/5 Computing Nat 4/5 Computing ScienceScience

Translator ProgramsTranslator Programs

Lesson AimsLesson Aims By the end of this lesson: All pupils will be able to:

Describe and compare the following types of languages:

Machine Code High Level Languages Describe why High Level Languages require

translation. Describe how interpreters and compilers

function.

Types Of LanguagesTypes Of Languages Machine Code is made up of only 2

symbols. 1 and 0 (On and Off)

High Level Languages such as Visual Basic are written using some English words. They are not written IN english!

Nat 4/5

High Level LanguagesHigh Level Languages

Nat 4/5

Why do we need them?Why do we need them? The source code you write is instructions

for the computer They are in a High Level Language

The computer needs these instructions translated into machine code It’s the only language it understands!

Nat 4/5

Types of TranslatorsTypes of Translators These programs convert High Level

Language Source code into machine code (binary)

Interpreter Translates and executes one line at a time

Compiler Translates and executes the entire program

at once This program can then be ran repeatedly

Nat 4/5

Think complete!

InterpreterInterpreter Functions like a spoken language interpreter.

Translates and executes a single line at a time

The interpreter is ALWAYS loaded in memory

Error feedback is provided line by line Like in Smallbasic

Interpreted programs have to be re-interpreted every single execution

Nat 4/5

How an interpreter worksHow an interpreter works

Nat 4/5

Original Source Code

Pctoutput.print “Hello”

Pctoutput.isible = true

Interpreter

1001 1000 1100 1110 00111001 1000 1100 1110 0011Syntax Error

How the compiler worksHow the compiler works

Nat 4/5

Original Source Code

Pctoutput.print “Hello”

Pctoutput.isible = true

Compiler 1010 1010 1010 0111 00111001 1000 1100 1110 0011

Syntax Error

Object Code

Can be saved and ran later

SummarySummary Compilers translate source code once into

an executable program Only has to be translated once! Cannot see the source code in a compiled

program

Interpreters translate source code line by line Always has to be re-interpreted Spots errors line by line

Nat 4/5