Computing: chapter 2

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What is hardware?
The physical components of a computer system –including input, output, storage + processing devices.
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What is computer architecture?
The internal logical structure + organisation of the computer hardware. The von Neumann architecture is basis for all modern digital computers. All data + instructions are stored in RAM as binary numbers.
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What is the purpose of the CPU?
To carry out all processing in a computer. The control unit uses electrical signals to control the flow of data within the CPU - fetch, executes + decodes instrThe arithmetic + logic unit (ALU) carries out all of the arithmetic + logical operations.
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What is the boot sequence?
A sequence of processes that contain all the info + instructions to get the computer up and running. It contains the boot loader, a program that starts this sequence when the computer is switched on. Then the control is handed to the OS.
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What affects the speed at which a computer can process data?
The CPU clock speed (processor speed), cache memory + the number of processor cores.
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How does the CPU clock speed affect the speed of the CPU?
The speed of the fetch-execute cycle is determined by an electronic clock chip + measured in cycles per second (Hz). Processor speed = typically measured in gigahertz (GHz) billions of cycles per second
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How does cache memory affect the speed of the CPU?
Data in use is transferred to CM to make access to it faster. CPU cannot access main memory at same speed as the processor clock chip –transferring data from main memory causes significant delays. CM has similar access times to CPU but is expensive.
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How can the number of processor cores affect the speed of the CPU?
Multi-core processors use multiple CPUs working together so that data is processed simultaneously. However, more complicated operating systems ate needed to manage them.
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Describe Random Access Memory (RAM).
Volatile (data lost when power is switched off), can be accessed and changed by the computer at any time. Stores programs and data being used by the computer. Contains the operating system. Large (4GB< typically).
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Describe Read Only Memory (ROM).
Non-volatile (data retained when power is switched off), programmed during manufacture. Stores instructions + data required to start up computer. Contains boot program. Small (1 or 2 MB for boot program)
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What is virtual memory?
Part of the hard drive used as an extension to RAM when there isn’t enough RAM available to hold all data + programs required. Access to virtual memory=slower than to RAM. Increasing RAM reduces use of VM + improves performance of computer.
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What is flash memory?
Type of ROM that can be rewritten + is used as a portable medium for storing + transferring data.
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Why do computers use binary values?
As it is easy to tell the state of a switch: on/off or 0/1
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Why do we need input and output devices?
Computers are used to process data we supply in order to provide us with the required input + so a computer is of little value without accepting inputs and providing outputs.
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Why do we use secondary storage devices for computer systems?
Computers use RAM as working storage for processing data but it’s volatile (all data is lost when the power is switched off). Secondary storage is used to keep permanent copies of programs.
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What are magnetic hard disks?
Used to store the OS, installed programs + user data. Hard disks are reliable with a high capacity + low cost.
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Optical disks - pros, cons and uses?
As they are excellent for transferring files or distributing software. Advantages: good capacity, low cost & lightweight + portable. A CD can store 700MB + a DVD can store 4.7 GB.
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What are advantages and disadvantages of using magnetic tape to store data?
Low cost, high capacity(80MB-1TB), portable design in cassette tapes, normally used for backup or archiving, reliable if carefully stored but it’s a serial device (slow speed) + tape can be damaged by repeated use.
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What are the pros and cons of Magnetic Hard Drives?
Capacity (40GB-2TB), Internal speed (3GB/sec), external (480MB/sec), portable external drives + fixed internal drives, can write to disks countless times but external drives can crash as they are not meant to be moved when spinning. Back-up + archivi
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What are the advantages and disadvantages of Solid State Drives?
Typical Capacity (128 – 512 GB), High speeds (6GB/sec), durable (no moving parts so disk crash is avoided), most reliable of hard drives but isn’t portable.
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Why is flash memory useful – pros, cons and uses?
It consumes little power. Good capacity (but less maximum capacity than a hard disk), used in hand held devices, but more expensive than a hard disk.
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What are the main considerations when selecting storage?
Capacity, Speed (how quickly the data can be transferred), Portability, Durability and reliability.
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Other cards in this set

Card 2

Front

What is computer architecture?

Back

The internal logical structure + organisation of the computer hardware. The von Neumann architecture is basis for all modern digital computers. All data + instructions are stored in RAM as binary numbers.

Card 3

Front

What is the purpose of the CPU?

Back

Preview of the front of card 3

Card 4

Front

What is the boot sequence?

Back

Preview of the front of card 4

Card 5

Front

What affects the speed at which a computer can process data?

Back

Preview of the front of card 5
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