OCR A-Level Computer Science from 2015 - Chapter 8 (Applications Generation)


OCR A-Level Computer Science from 2015 - Chapter 8 (Applications Generation)
Tyrone Muriithi
Flashcards by Tyrone Muriithi, updated more than 1 year ago
Tyrone Muriithi
Created by Tyrone Muriithi about 7 years ago

Resource summary

Question Answer
What is a translator A program that converts source code into machine code
What is a mnemonic A memory device; something that makes difficult things easier to remember
What is an assembler A program that converts assembly language into object
What is an interpreter A program that converts high-level language into machine code and runs it line by line
Advantage of an interpreter Useful for debugging a program ca start running straight away and will stop at a line if it finds an error
Disadvantage of a interpreter An interpreted program runs slowly. Every time the program is run, the user has to wait for translation of each line as well as the execution
What is a compiler A program that takes a program written in a high-level language and converts it to object code
Advantages of a compiled program -Much faster than an interpreted program -Reduces risk of plagiarism because compiled code is not human-readable
What are the 4 stages of compilation 1)Lexical Analysis 2)Syntax Analysis 3)Code Generation 4)Optimisation
What is involved within the first stage of compilation -All comments and whitespace are removed from the program -High-level code is turned into a series of tokens
What is a reserved word A word that has a special meaning in the programming language and as such cannot be used as a variable name. Examples in many languages include if, else, while and for
What is involved in the second stage of compilation The compiler checks that the code that has been written uses a valid syntax This stage will also produce an abstract syntax tree from the tokens that will represent the program
What is involved in the third stage of compilation The compiler converts the abstract syntax tree into object code
What is involved in the fourth stage of compilation This stage involves improving the code to make it run as quickly as possible or with using as little memory as possible
How is the code changed in the fourth stage of compilation If the optimiser finds lines of code which have no effect on the program, they are removed It can also replace instructions or groups of instructions with better alternatives
What is a library A collection of precompiled routines that a program can use
Examples of libraries OpenGL, OpenSSL and Havok
What is a linker A program that combines library code with the compiled code to produce a final single executable program
What is Static Linking All the library code needed is put directly into the program when it is compiled. This means that the final program can be large in size
What is Dynamic learning When compiled versions of the library are stored and the operating system links a program to them when it is run
What is a loader A part of the operating system that is responsible for loading a program into memory
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