Components of a Computer System

Question 1

Define what is meant by hardware.

Answer 1

• The physical components that make up a computer system.

- E.g. RAM stick, cooling fan, mouse.

Question 2

Define what is meant by software.

Answer 2

• The programs or applications a computer can run.

- E.g. Word processor, Internet browser, file manager.

Question 3

What is an embedded system?

Answer 3

• A computer system built into another device.

Question 4

Give two examples of an embedded system.

Answer 4

• Dishwasher
• Mp3 Player
• Digital Thermometer
• Washing Machine
• Manufacturing Machine

Question 5

Explain two benefits of having an embedded system.

Answer 5

• Embedded systems are far smaller than general purpose computers.
• Embedded systems are cheaper to produce than general purpose computers.
• Embedded systems tend to be more reliable than general purpose computers which mean they are less likely to break.

Question 6

What does the CPU stand for?

Answer 6

• The Central Processing Unit

Question 7

State two functions of the Control Unit.

Answer 7

• The Control Unit executes instructions.
• It follows the Fetch-Decode-Execute cycle.
• It controls the flow of data within the CPU.
• It controls the flow of data between the CPU and other parts of the computer system, (such as memory, and input and output devices).

Question 8

Describe the function of the Arithmetic Logic Unit.

Answer 8

• The ALU carries out arithmetic operations, e.g. multiplication and subtraction.
• It performs logic operations on binary data, such as AND, NOT, and OR.

Question 9

Explain how cache is used by the CPU.

Answer 9

• The cache is extremely fast memory in the CPU.
• It stores regularly used data or instructions.
• The CPU can access data stores in the cache much faster than retrieving it from RAM.

Question 10

Explain the purpose of CPU registers.

Answer 10

• The registers are super fast memory that store tiny amounts of data or instructions that the CPU can access extremely quickly.

Question 11

Outline the function of the following:

• Accumulator
• MAR
• MDR

Answer 11

• The accumulator stores the results of calculations done by the ALU.
• The MDR holds any memory address about to be used by the CPU.
• The MDR holds data or instructions that have been fetched from / to be written to memory.

Question 12

Describe what happens in the Fetch-Decode-Execute cycle.

Answer 12

Fetch:

• The memory address from the program counter is copied to the MAR.
• An instruction is fetched from memory in the MAR.
• The fetched instruction is copied into the MDR.
• The value in the program counter is changed to point to the address of the next instruction.

Decode:

• The fetched instruction is decoded by the CU.
• A new value may be loaded into the MAR / MDR prepares to execute the next step.

Execute:

• The decoded instruction is carried out.
• The cycle is repeated.

Question 13

Describe the difference from volatile and non-volatile memory.

Answer 13

• Volatile memory is temporary memory - it requires power to retain its data content.
• Non-volatile memory retains its data content even after when there is no power.

Question 14

Explain the purpose of RAM in a computer system.

Answer 14

• RAM holds data that is currently in use.
• E.g. programs, OS, files, documents.
• It allows the CPU to directly access data much faster than if the data was on secondary storage.

Question 15

State two functions of the BIOS.

Answer 15

• The BIOS loads the operating system.
• It performs a variety of self-diagnostic tests on the hardware, e.g. testing RAM.
• It checks for hardware connected to the computer.
• It provides a basic user interface where some settings can be accessed, e.g. changing which storage device to load the OS from.

Question 16

Explain why the BIOS is stored in ROM instead of RAM.

Answer 16

• The BIOS must be stored in non-volatile memory, so its contents aren’t lost when the computer is turned off.
• ROM is non-volatile memory but RAM is volatile memory.
• The contents of the BIOS should not be changed. ROM is Read-Only Memory, but RAM is not and can be altered.

Question 17

Explain how virtual memory works.

Answer 17

• Virtual memory is an area of secondary storage that the computer uses to store the contents of RAM temporarily when there isn’t enough space in RAM to store necessary / data.
• The computer will copy the items not currently in use from RAM to virtual memory, freeing up space in RAM.

Question 18

Explain one disadvantage of using Virtual memory.

Answer 18

• Virtual memory can make a computer slow to respond, e.g. when switching between applications, because data transfer speeds from secondary storage are much slower than from RAM.

Question 19

Define the term clock speed.

Answer 19

• Clock speed is the number of instructions a CPU / processor core can carry out per second.

Question 20

Explain why using a CPU with large cache capacity may improve CPU performance.

Answer 20

• Cache is much faster than RAM.

- The larger the cache, the more data can be stored for quick access by the CPU, meaning the CPU should perform better.

Question 21

Give three characteristics to consider when choosing a type of secondary storage.

Answer 21

• Capacity
• Reliability
• Cosy
• Portability
• Data transfer speed
• Durability

Question 22

Explain why flash memory is suitable for an action camera.

Answer 22

• Flash storage / solid state storage is resistant to impacts, so it is unlikely to be damaged when the action camera is in use.
• Flash storage can be very compact and lightweight.

Question 23

Explain why a magnentic hard disk would be unsuitable for an action camera.

Answer 23

• Magnetic hard disks are much larger and heavier than flash storage devices, making them unsuitable for a small, lightweight camera.
• Magnetic hard disks can be damaged greatly by impacts, so they would be unsuitable in an action camera.

Question 24

What type of storage device is suitable for daily back-ups?

Answer 24

• Magnetic Tapes

Question 25

Outline the advantages and disadvantages for using Magnetic Tape for back-ups.

Answer 25

Advantages:

• Magnetic Tape is much cheaper per GB than other forms of secondary storage.
• Tape has a much larger data capacity than other forms of storage.
• Tape has a higher read/write speed than HDDs.

Disadvantages:

• It can take far longer to find a specific piece of data on tape, e.g. to recover certain files from a back-up.
• Tape reading drives can be very expensive.
• Data can be corrupted if placed near a strong magnet.

Question 26

State three functions of an Operating System.

Answer 26

• The OS communicates with hardware via device drivers.
• The OS provides a User Interface.
• The OS provides a platform for software / applications to run.
• The OS allows a computer to multi-task by controlling memory / CPU resources.

Question 27

Describe what is meant by device drivers.

Answer 27

• Device Drivers are pieces of software that allow the OS and hardware to communicate with each other.

Question 28

Identify two ways how an OS can help protect a User’s personal data.

Answer 28

• They often allow different user accounts, giving each user access to their own personal data and desktop, which cannot be accessed by other users.
• It may have anti-theft measures, like password or pin protection.
• It may include encryption software, to allow users protect their files.
• It may include anti-virus software or a firewall to help protect against unauthorised users / software.

Question 29

Explain how an OS can help a computer multi-task.

Answer 29

• When an applications are opened, the OS moves the necessary parts are moved to memory.
• The OS will remove unneeded data from memory, e.g. when programs or files are closed.