Standard Grade Computing Studies

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Standard Grade Computing Studies COMPUTER SYSTEMS
2008
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1 Systems Software
G/C

• High Level Languages (HLL)
• HLLs are special languages used by programmers to
  code computer programs.
• They have in common
• Are similar to English
• Need to be translated to machine code for the
  processor.
• Examples
• HTML, Basic, Java, C etc.

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1 Systems Software
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• Purpose of High Level Languages
• HLLs allow programmers to
• concentrate on solving problems
• provide help when debugging programs.

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Need for Translation A translator program is
needed to change a program from HLL to machine
code. HLLs such as Basic and Java have their own
specific translator programs.
HLL Code
Machine Code
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1 Systems Software
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• Types of translator
• There are two types of translators interpreters
  and compilers.
• An interpreter translates the program a line at a
  time as the program is running.
• A compiler takes the entire source code of a
  program and translates it into a machine (object)
  code version that is stored.

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Portability of Software Programs can run on
different computer systems i.e. processors,
operating systems, without being altered.
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2 Operating Systems
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Operating System (OS) An OS is a set of programs
that enable a computer system to function. It
controls the computer and any devices connected.
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2 Operating Systems
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Directories and folders One of the OSs jobs is
to manage the transfer of programs and data to
and from backing storage. The OS allows users to
organise their files into directories. In
Windows OS, a directory is called a folder.
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2 Operating Systems
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Interactive Systems An interactive operating
system responds to commands issued by the user.
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Real time systems.
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• Types of Files
• There are two types of files
• Program files are the executable machine code
  files for software such as Microsoft Powerpoint
  i.e. winword.exe
• Data files are created by software applications.
  A Powerpoint data file is a. presentation save
  with the extension .ppt.

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2 Operating Systems
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Functions of the OS.
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2 Operating Systems
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Background job capability.
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2 Operating Systems
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Device Drivers
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2 Operating Systems
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Hierarchical Filing System A system that allows
folders and sub-folders to be created within to
organise files.
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Sequential and Random Access to data
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3 Low-Level Machine
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Stored Program
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3 Low-Level Machine
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Main Memory Size
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3 Low-Level Machine
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Input Process Output (IPO)
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3 Low-Level Machine
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Processor
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3 Low-Level Machine
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Main Memory
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3 Low-Level Machine
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Machine Code
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3 Low-Level Machine
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Positive Whole Numbers
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3 Low-Level Machine
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Text
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3 Low-Level Machine
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B/W Bitmapped Graphics
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3 Low-Level Machine
C
Calculation of Storage Requirements B/W Bitmaps
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3 Low-Level Machine
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Processor Structure
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3 Low-Level Machine
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Word
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3 Low-Level Machine
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Addressability
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4 Hardware
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Addressability