Hardware (2)

Question 1

(Exam-style question)

Zakir wants to buy a new laptop.

Explain why the laptop needs both hardware and software. (2)

Answer 1

Any one from:

• Software allows instructions to be passed to the hardware so that it can carry out tasks
• Software is the set of instructions that controls the hardware

Question 2

Give some factors that affect the performance of the CPU.

Answer 2

• Clock speed
• Number of processor cores
• Size of cache
• Type of cache

Question 3

Give one benefit of having a higher clock speed.

Answer 3

Any one from:

• More instructions can be carried out per second
• Processes run faster
• Programs executed faster

Question 4

Give one drawback of having a higher clock speed.

Answer 4

Any one from:

• The CPU/computer could overheat
• More cooling required
• Needs more power

Question 5

(Exam-style question)

Increasing the size of the cache will improve the performance of the CPU.

Explain how increasing the size of the cache improves the performance. (2)

Answer 5

Any one from:

• Cache stores frequently used data so the processor does not have to wait because cache is checked before main memory / because RAM is further away from the processor
• It speeds up processing because cache is a faster type of memory

Question 6

Describe the speed, closeness and accessibility of each level of cache.

Answer 6

• Level 1 (L1) cache - extremely fast, usually embedded in the CPU, closest to the processor
• Level 2 (L2) cache - slower than L1 cache, one stage further from the processor, may be located on CPU or separate chip
• Level 3 (L3) cache - specialised memory that works to improve performance of L1 and L2, can be significantly slower than L1 or L2 cache, usually double speed of RAM

Question 7

Describe the effect having a greater number of cores has on the performance of the CPU.

Answer 7

• The performance increases
• CPUs with multiple cores have more power, allowing for more processes to be ran at the same time with greater ease

Question 8

Give some differences between primary storage and secondary storage.

Answer 8

Primary:

• Volatile
• Short-term
• Directly accessed by CPU
• Limited storage capacity

Secondary:

• Non-volatile
• Long-term
• Programs/data must be transferred to memory in order for them to be accessed by CPU
• Large storage capacity

Question 9

(Exam-style question)

Describe one reason a computer needs both primary and secondary storage. (4)

Answer 9

• Primary storage is needed to provide the CPU with fast, direct access to the program instructions and data that it is currently using - it only retains its contents temporarily
• Secondary storage is non-volatile and is needed to keep programs and data for the long term when not in use

Question 10

Give the three main types of secondary storage.

Answer 10

• Magnetic
• Optical
• Solid-state

Question 11

Describe how how data is stored using magnetic storage.

Answer 11

• Use of read-write heads that contain electromagnets
• Parts of surface is either magnetised (1) or demagnetised (0), read-write heads control this when writing and can tell what state surface of disk is in when reading

Question 12

Describe how data is stored on optical media.

Answer 12

Write data:

• Laser used to burn pits and lands into surface of disk
• More reflective areas ‘lands’ represent 1s and less reflective areas ‘pits’ are 0s

Read data:

• Laser beam shone onto surface of disk - light that hits a land reflects differently to where it hits a pit
• Amount of light reflected translates to 1s & 0s by a sensor

Question 13

Describe how data is stored on a solid-state drive.

Answer 13

Write data:

• Electrical current applied to transistor, forcing electrons through a barrier and trapping them in pools
• Full pool represents 0 and an empty pool 1

Read data:

• Small voltage is applied
• If electron pool is empty, transistor turns on and 1 is read - if full, transistor does not turn on and 0 is read

Question 14

Give instances in which magnetic storage is used, and give advantages and disadvantages of using this form of secondary storage.

Answer 14

Used in:

• HDDs
• Internal/external hard drives
• Tape drives

Advantages:

• High capacity
• Fast data access

Disadvantages:

• Has moving parts that will eventually fail
• Noisy

Question 15

Give instances in which optical storage is used, and give advantages and disadvantages of using this form of secondary storage.

Answer 15

Used in:

• CD, DVD and Blu-ray drives

Advantages:

• Portable
• Disks are cheap

Disadvantages:

• Slow to access
• Prone to scratches

Question 16

Give instances in which solid-state storage is used, and give advantages and disadvantages of using this form of secondary storage.

Answer 16

Used in:

• Solid-state drives
• USB sticks
• SSD cards
• Mobile devices and wearables

Advantages:

• Very fast data access
• No moving parts
• Low power
• Quiet

Disadvantages:

• Relatively expensive
• Has a limited number of read-write cycles

Question 17

Describe what is meant by ‘cloud storage’.

Answer 17

Data is stored and is accessible from multiple connected resources that comprise a cloud via the internet

Question 18

List some advantages of using cloud storage.

Answer 18

• Unlimited storage capacity - cloud computing offers limitless storage
• Automatic backup - hard disk crash could destroy valuable data that is stored on a device, but if the data is stored in the cloud, computer crash should not affect it
• Universal access - all documents and files stay in the cloud, can be accessed whenever you have a computer or phone with internet connection; all documents instantly available wherever you are
• Device independence - user not limited to having documents stored on a single computer or network, can change device and documents follow you through cloud

Question 19

List some disadvantages of cloud storage.

Answer 19

• Requires a reliable internet connection, impossible without a connection
• Will not work as well with low-speed connections
• Large documents and images require a lot of bandwidth
• User loses control over what happens to data as this is managed by cloud service provider

Question 20

What is an embedded system?

Answer 20

A specific-purpose computer within a larger system

Question 21

List some features of an embedded system.

Answer 21

• Specific-purpose
• No or minimal user interface
• Low power consumption
• Its functionality cannot be changed/upgraded by users
• Functions in real time
• Uses sensors to interact with external environment
• Has customised software and hardware
• Has limited, integrated memory
• Small physical size