Components of a Computer System Flashcards
What is a computer?
A computer is a machine that processes data
Define hardware.
The physical stuff that makes up your computer system
Define software.
The programs that a computer system runs
Give some examples of system software.
1) operating systems
2) utilities
Give some examples of application software.
1) word processors
2) web browsers
3) email clients
4) games
What is an embedded system.
Embedded systems are computers built into other devices
Explain the role of the control unit in the CPU.
1) to execute program instructions by following the fetch-decode-execute cycle
2) controls the flow of data inside the CPU (to registers, ALU, cache) and outside the CPU (to main memory and input/output devices)
What does ALU stand for?
Arithmetic Logic Unit
What does the ALU do?
1) completes simple addition and subtraction
2) compares the size of numbers
3) can do multiplications and divisions using repeated addition and subtractions
4) performs logic operations such as AND, OR and NOT
5) performs binary shifts
What is cache?
Very fast memory in the CPU
What is cache used for?
To store regularly used data so that the CPU can access it quickly the next time it’s needed
Describe the function of the clock.
Used to synchronise when instructions will be carried out (like a metronome)
What is a bus?
A collection of wires that are used to transmit data between components of the CPU and other parts of the computer system
Describe what happens at each stage of the CPU fetch-decode-execute cycle.
1) fetch - the control unit reads the memory address of the next CPU instruction. The instruction stored in that address is copied from memory to one of the registers. The memory address in the control unit is incremented to point to the address of the next instruction, ready for the next cycle
2) decode - the instruction that was copied from memory is decoded by the control unit. The control unit prepares for the next step
3) execute - the instruction is performed
What is volatile memory?
Temporary memory that requires power to retain its data
What is non-volatile memory?
Permanent memory that keeps its contents even when it has no power
What does RAM stand for?
Random Access Memory
Describe how RAM is used in a computer system.
To store all data, files and programs when they’re being used
Explain why ROM is required by a computer system.
It contains all the instructions a computer needs to properly boot up. These instructions are called the BIOS (Basic Input Output System)
Which usually has more RAM: an embedded system or a non-embedded system?
Non-embedded systems
What characteristics of a processor may affect its performance?
1) clock speed
2) CPU cores
3) cache size
4) cache type
Define primary storage.
The memory areas that the CPU can access directly
Define secondary storage.
Non-volatile storage that isn’t directly accessible by the CPU
Give some examples of primary storage.
1) CPU registers
2) cache
3) ROM
4) RAM
Give some examples of secondary storage.
1) magnetic hard disk drives
2) solid state drives
3) CDs
4) SD cards
What are the advantages of a HDD compared to a SSD?
1) HDDs are cheaper
2) both are high capacity, but HDDs are higher
3) HDDs have a longer read/write life than SSDs - SSDs can only be written a certain number of times before they begin to deteriorate
What are the advantages of a SSD compared to a HDD?
1) SSDs are faster
2) SSDs don’t need defragmenting
3) SSDs are more shock-proof than HDDs
4) HDDs make some noise, SSDs are silent
Why might someone choose magnetic tape as a form of storage?
It has a very high capacity and an extremely low cost per GB
List some uses of flash memory.
1) cameras
2) smartphones
3) tablets
What are the pros of optical discs?
1) they’re very cheap per GB
2) portable
3) won’t be damaged by water or shocks
What are the cons of optical discs?
1) they are easily scratched
2) modern devices don’t have optical drives
3) they can’t compete with flash storage devices due to their low capacity per disc, very slow read/write speeds and poor reliability of RW discs
What are the pros of cloud storage?
1) users can access files from any connected device
2) files can be shared with others or made public
3) easy to increase how much storage is available
4) no need to buy expensive hardware to store data
5) no need to pay IT staff to manage the hardware
6) cloud host provides security and backups for you
7) can be cheap/free if not much storage is required
What are the cons of cloud storage?
1) need connection to the Internet to access files
2) upload/download speed depends on bandwidth
3) dependent on host for security and backups
4) stored data can be vulnerable to hackers
5) unclear who has ownership over cloud data
6) subscription fees for using cloud storage may be expensive in the long term
What are the functions of an operating system?
1) to communicate with input and output devices via device drivers
2) provide a platform for applications to run on, and a user interface
3) control memory management and allocation
4) organise the CPU and its processing tasks
5) deal with file management and disk management
6) manage system security and user accounts
Explain how device drivers are used in a computer system.
Device drivers acts a ‘translator’ for the signals between the OS and the device
Describe how the OS manages applications.
1) provides a platform for applications to run on and multitasks
2) allows applications to access hardware, peripheral devices, RAM and secondary storage
3) provides a user interface that applications are accessed through
Describe how the OS manages memory.
1) decides if applications or features have been used recently - if not, they may be removed from memory
2) manages how much RAM a program has access to
3) when running multiple applications at once, will make sure that they don’t overwrite or interfere with each other by allocating certain applications certain memory addresses, keeping their processes in separate locations
Describe how the OS manages the CPU.
1) scheduling to determine the most efficient order for the CPU to execute instructions
2) interrupts the current CPU process if a higher-priority process becomes available
Describe how the OS manages files and disk space.
1) manages the hard disk - splits the physical disk into storage sectors, decides which sector to write data to, and keeps track of free space on the disk
2) organises and maintains the hard disk with utility software like defragmentation software
Give ways in which an OS might keep your files secure.
1) user account control
2) anti-theft measures
3) passwords
4) pins
5) fingerprint scanners
6) retina scanners
List some types of utility software and explain what they do.
1) defragmentation - puts the files back into one block and collects the free space together
2) disk health - scans the drive for problems and fixes issues where possible
3) compression - reduces the size of files so they take up less disk space
4) encryption - scrambles (encrypts) data to stop third-parties from accessing it
5) backup - copies the computer system’s files and settings and stores them externally so that they can be restored in the event of data loss
6) virus scanners - inspects each file on your computer, looking for virus
7) system cleanup - go through and get rid of temporary files left on your hard drive which can end up taking up lots of space unnecessarily
