Computer Systems Flashcards
What is a Computer’s purpose?
To take data, process it and output it
What is Hardware?
Physical components such as:
CPU, motherboard, monitor, printer
What is Software?
Programs or applications that can be run on the Computer System, such as:
Operating System, Word Processors and Video Games
What are Peripherals?
External hardware connected to a computer, such as:
Keyboard, Mouse and Printers
What is an Embedded System?
A computer built into another larger system
What are the 3 components of the CPU?
The Control Unit (CU)
The Arithmetic Logic Unit (ALU)
The Cache
What is the Control Unit?
The overall control of the CPU,
Manages the fetch-decode-execute cycle (controls data flow),
Contains the Program Counter
What is the Arithmetic Logic Unit?
Where calculations are done, and decisions are made,
Contains the Accumulator register
What is the Cache?
Very fast memory, is slower than registers but faster than RAM,
Stores regularly used data,
Has a very low capacity and is expensive compared to RAM
What are registers?
small amount of fast temporary memory within the processor where the ALU or the CU can store and change values needed to execute instructions.
What are registers? With examples?
Small amounts of fast temporary memory,
Where ALU or CU can store and change values needed to execute instructions
Examples: accumulator, program counter, memory address register, memory data register
What is the Accumulator?
Stores results of calculations from the ALU
What is the Program Counter (PC)?
Holds the Memory Address of the instructions for each cycle
What is the Memory Address Register (MAR)?
Holds any Memory Address about to be used by the CPU
What is the Memory Data Register (MDR)?
Holds the actual data or instructions
What is the Memory Data Register (MDR)?
Holds the actual data or instructions
Describe the FETCH-DECODE-EXECUTE cycle
Fetch - copy memory address from the PC to the MAR,
copy the instruction stored in the MAR address to the MDR
Decode - the instruction in the MDR is decoded by the CU
Execute - the instruction is performed
What 3 things could affect on CPU Performance?
Clock Speed
Number of Cores
Cache Size
What is Clock Speed?
Number of cycles a single processor core carries out per second (Hz),
The higher the Clock Speed, the greater the number of cycles carried out per second
What is Cores?
Processes data independently to each other core,
The more cores a CPU has, the more instructions it can carry out at once, so the faster it can process data
What is Cache Size?
Data storage inside the CPU,
Much faster than RAM,
A larger CPU Cache gives the CPU faster access to more data it needs to process
What is Volatile Memory?
Temporary Memory,
Requires power to retain data
What is Non-volatile Memory?
Permanent Memory,
Keeps its contents even when it has no power
What is Virtual Memory?
A section of Volatile Memory created temporarily on the storage drive,
Only used when RAM is full,
Holds less frequently needed data
What is Random Access Memory (RAM)?
Used to store: data currently in use, programs in use
Is Volatile, can be Read and Written to
What is Read Only Memory (ROM)?
Used to store: start-up routines (BIOS, Basic Input Output System)
Is Non-Volatile, can only be Read
What are the two main tiers of Storage?
Primary Storage - memory areas that CPU can access very quickly, mostly Volatile, fastest Read/Write speeds
Secondary Storage - where all data is stored when not in use, Non-Volatile, much slower Read/Write speeds
Advantages of Hard Disks compared to Solid State Drives
Cheaper,
Higher Capacity,
Longer Read/Write life
Advantages of Solid State Drives compared to Hard Disks
Faster,
Doesn’t need defragmentation,
More Shock-proof,
Is Silent
What are the 3 types of Secondary Storage?
Magnetic,
Optical,
Solid State
What is Defragmentation?
It reorganises data on the hard drive to put fragmented files back together,
What is Compression?
Reduces the size of files by permanently or temporarily removing data from them,
Compressed files take up less disk space and are quicker to download
What is Encryption?
It scrambles data to stop third-parties from accessing it,
Main benefit is that stolen data is still secure,
To decrypt data a special ‘key’ is needed
