Topic 4 - Computer Systems (key points of spec)

Question 1

4.1 - Define the terms hardware and software and understand the relationship between them.

Answer 1

Hardware is the physical component of a computer. Software is the programs that run on a computer.
A relationship between them is that a computer system can’t function without software AND hardware.

Question 2

4.3 - Explain what is meant by: system software, application software

Answer 2

System software is any software that assists with the running or management of the computer system. Application software is any software added to the system that enables the user to perform a task.

Question 3

4.3 - Give examples of both types of software.

Answer 3

System software:
game engines, utility programs, encryption, backup
Application software:
word processors, internet browsers, games

Question 4

4.3 - What does the operating system handle the management of?

Answer 4

processors, memory, i/o devices, applications, security

Question 5

4.3 - What is the need for operating systems and utility programs?

Answer 5

Operating systems control computer hardware and act as an interface with application programs. Utility software helps to manage, maintain and control computer resources.

Question 6

4.4 - Explain the von Neumann architecture

Answer 6

Von Neumann architecture is the design upon which many general purpose computers are based

Question 7

4.4 - Explain the role and operations of main memory and the following major components of a central processing unit (CPU)

Answer 7

Memory is the area where the computer stores or remembers data. Memory provides the CPU with its instructions

Question 8

4.4 - Explain the role and operations of the Arithmetic Logic Unit

Answer 8

Performs two sets of operations on data.
Arithmetic operations (+-), logical operations (is A>B?)

Question 9

4.4 - Explain the role and operations of the Control Unit

Answer 9

control unit coordinates and controls all of the activities taking place within the CPU. it decodes instructions and executes them. also receives signals from the system clock

Question 10

4.4 - Explain the role and operations of the Clock

Answer 10

controls the timing of the processor, synchronizes all CPU operations

Question 11

4.4 - Explain the role and operations of the bus

Answer 11

collection of wires through which data is transmitted from one component to another. used to send control signals and data between the processor and other components

Question 12

4.4 - Explain the effect of the clock speed on the performance of the CPU.

Answer 12

higher clock speed determines how many cycles the CPU can deal with in a second

Question 13

4.4 - Explain the effect of the number of processor cores on the performance of the CPU.

Answer 13

multiple cores will give the CPU more power to run multiple programs at once but some of the extra speed will get used up as the cores have to communicate with each other through channels.

Question 14

4.4 - Explain the effect of the cache size on the performance of the CPU.

Answer 14

the bigger its cache, the less time a processor has to wait for instructions to be fetched.

Question 15

4.4 - Explain the effect of the cache type on the performance of the CPU.

Answer 15

the higher the memory size, the more powerful the cache size.

Question 16

4.4 - Understand the fetch-execute cycle.

Answer 16

fetch: the next instruction is fetched to the CPU from main memory.
decode: the instruction is decoded to work out what it is
execute: the instruction is executed.

Question 17

4.4 - Understand the differences between Main memory and secondary storage.

Answer 17

Main memory:
volatile, fast to read/write, directly accessible by the CPU.
Secondary Storage:
non-volatile, slow to read/write, not directly accessible by CPU.

Question 18

4.4 - Understand the differences between RAM and ROM

Answer 18

ROM can be read not written, helps boot up the computer, used a lot in embedded systems such as dishwashers, microwaves, etc
RAM can be read and written, it is volatile and used to store running programs and operating systems.

Question 19

4.4 - Understand why Secondary Storage is required.

Answer 19

Secondary storage is needed to keep programs and data. Without it, all programs and data would be lost the moment the computer is switched off.

Question 20

4.4 - Explain the operations of solid-state storage

Answer 20

Data is recorded onto solid memory chips without any moving parts. SSD’s use electrical circuits to store data.

Question 21

4.4 - Explain the operations of magnetic storage.

Answer 21

mechanical parts move over disks surface to read and write data magnetically.

Question 22

4.4 - Explain the operations of optical storage

Answer 22

lasers read and write data using light.

Question 23

4.4 - list advantages and disadvantages of magnetic storage

Answer 23

advantages:
cheap, large storage capacities, fast write speed
disadvantages:
lots of mechanical parts, durability is an issue

Question 24

4.4 - list advantages and disadvantages of optical storage.

Answer 24

advantages:
cheap, portable, takes up little space physically
disadvantages:
less storage capacity, easily damaged, slow write speeds.

Question 25

4.4 - list advantages and disadvantages of solid-state drives

Answer 25

advantages:
highly durable, no moving parts, very fast read/write speeds, fast start-up times
disadvantages:
more expensive than magnetic hard disks, similar storage capacity as magnetic disks.

Question 26

4.4 - Explain the term ‘cloud storage’.

Answer 26

Cloud storage uses magnetic and increasingly solid-state storage at a remote location. Cloud storage refers to saving data in an off-site storage system maintained by a third party. e.g - google drive, dropbox.

Question 27

4.4 - list advantages and disadvantages of cloud storage compared to local storage

Answer 27

advantages:
easy to use, companies offer high data storage capacity, convenient to use.
disadvantages:
data cannot be accessed without internet, company needs to trust that their security can stop a data breach.

Question 28

4.4 - Understand the term ‘embedded system’ and explain how an embedded system differs from a non-embedded system

Answer 28

In an embedded system, CPU speed is slow whereas it is very fast in non embedded.
Software has one purpose and cannot install new software in an embedded system whereas new software can be installed in a non embedded system.
Embedded systems have programs stored on ROM whereas non embedded have programs stored on hard drives.

Question 29

4.4 - Understand the term ‘embedded system’

Answer 29

An embedded system is a single microprocessor that includes RAM, ROM, and a CPU. it is frequently used to control a device using simple inputs.