Computer Systems Flashcards
Binary
A two-state system, where only 1 or 0 can be used
Denary
Our number system that uses 10 digits
Bit
A binary digit
Floating point representation
Method a computer uses to store real numbers
Mantissa and exponent
Two parts of a floating point representation number
ASCII
Standard code that all computer systems use to represent text
Control characters
ASCII codes that are used to perform actions rather than display a character e.g. delete and tab etc.
Printable characters
ASCII codes that are used to display characters on the screen e.g. A, ! etc.
Bit mapped graphics
A method of representing graphics that stores information on each individual pixel
Vector graphics
A method of representing graphics that stores shapes as list of attributes e.g. coordinates of corners, line thickness, fill colour etc.
Advantages of vector graphics
Can be resized without loss of quality and have a smaller file size than bit mapped graphics
Advantages of bit mapped graphics
Can be edited at pixel level and can display more realistic images than vector graphics
Processor (CPU)
The part of the computer system that handles the instructions used to ensure that hardware and software respond as expected
Arithmetic and Logic Unit (ALU)
Part of the processor that performs calculations and makes decisions
Processor Speed
Referred to as Clock Speed and is measured in Megahertz (MHz) or Gigahertz (GHz).
Registers
Part of the processor that temporarily stores data
Control Unit
Part of the processor that fetches and executes instructions
Main memory
Consists of RAM (Random Access Memory) and ROM (Read Only Memory)
Random Access Memory (RAM)
Volatile memory that stores the programs and data currently being used
Read Only Memory (ROM)
Non-volatile memory
Bus
Collection of wires used to transmit information in a computer system
Memory location
Main memory consists of millions of these
Addressability
Each memory location has a unique address
Address bus
A uni-directional bus that holds the address of the memory location being accessed
Data bus
A bi-directional bus that carries data between the processor and memory
High level language
Programming language that uses English like words and needs to be translated into machine code
Machine code
Computer specific language that consists of 0s and 1s
Compiler
Translates the whole high level language into machine code and saves the machine code version
Interpreter
Translates the high level language into machine code one line at a time
Advantages of interpreters
It reports errors at the end of each line so it is easier to correct your mistakes. It takes less memory than a compiler when translating the program into machine code.
Advantages of compilers
The machine code file is saved so it never needs to be translated again. It takes less memory when executing the machine code program than an interpreter.
Disadvantage of a compiler
It takes more memory when translating the program compared to an interpreter.
Disadvantage of an interpreter
The high level language program needs to be translated into machine code every time the program is run.
Firewall
Blocks attempts to access a device and filters incoming traffic
Encryption
Data is encoded so that if it is intercepted it is unreadable
Keys
Used to encrypt and decrypt data
Brightness and standby mode
Two settings on a monitor which reduces energy use
