Computer Systems

What is hardware?

the physical components of the computer system

What is software?

program code which is executed to perform a task

What is application software?

programs that complete a specific task for the user

What are examples of application software?

• word processors

• web browsers

• spreadsheet software

What is system software?

software that controls and maintains the computer and its components

What are examples of system software?

• operating system

• utility programs

• library programs

• translators

What is the operating system?

a virtual machine for users to use the computer with ease, hiding the true complexity

What does the operating system manage?

• memory management

• processor scheduling

• handling interrupts

What do utility programs do?

housekeeping such as:

• data backup

• defragmenting hard drives

• data compression

• encryption

What do library programs do?

contains useful functions frequently used by a program to simplify development

What are translators and the three types?

software which translates between types of language

• compilers

• assemblers

• interpreters

Describe machine code and its advantages/disadvantages

• low level language of 1s and 0s

• directly manipulates the processor

• very long and difficult to understand

• difficult to debug

• useful for embedded systems

Describe assembly language and its advantages/disadvantages

• simplifies writing computer programs by using mnemonics in place of binary

• therefore more compact and less error prone

• each instruction has a one-one correlation to machine code

Describe high level languages

• not processor specific

• must be translated by compiler or interpreter

• easy to learn and understand

• built in functions

• use of variables, indentation and commenting make easier to debug

What is an imperative high level language?

language formed from instructions that specify how to complete a task rather than what a computer should do

Explain the job of an assembler

• translates assembly language into machine code

• platform specific

• one-one relationship

• quick and straight forward

Explain the job of compilers

• translates high level languages into machine code

• platform specific

• checks source code for errors line by line

• translates the entire program at once

• can be run without other software present

• will not be translated if there is an error

Explain the job of an interpreter

• translates line by line

• checks for errors as translated

• source code and interpreter must be present

• poor protection of source code

What are compilers with intermediate languages?

• translates source code into most commonly bytecode

• can be executed on different processors with a virtual machine

• allows for platform independence

What is a half adder used for?

adding two boolean values