3.4

Question 1

Define hardware.

Answer 1

-physical components of a computer such as the CPU, keyboard, mouse, GPU, primary and secondary storage

Question 2

Define software.(2)

Answer 2

-Programs that run on a computer including the operating system, applications such as Word Processing, spreadsheets and games
-Computer code that gives instructions to the hardware

Question 3

What is the function of the RAM?(2)

Answer 3

-Random Access Memory
-very fast and volatile memory
-When a program is to be executed, must be loaded from hard disk into main memory so that processor can access the instructions.
-Used by the computer to store programs currently being executed as well as the data it is currently being worked with or might need to be worked with soon.
-Average laptop has 4-8GB of Ram.
-Some might have 64GB.

Question 4

What is the function of the GPU?(2)

Answer 4

The GPU is the Graphics Processing Unit and is specifically designed for graphics instructions and calculations.
Important for gaming/video editing/3D rendering.

Question 5

What is the function of the motherboard?(2)

Answer 5

The circuit-board that all other components are mounted on.
Contains the electric components that allow each of the main elements of a computer to talk to each other.

Question 6

What is the function of secondary storage?(2)

Answer 6

Non volatile storage for storing data/instructions even after power is removed.
Hard disks drives and solid state drives(SSD) the most common types of secondary storage inside a computer. May also contain Optical Drives.

Question 7

What is the CPU made up of?

Answer 7

ALU, CU, Clock, Registers, Buses.

Question 8

What is the function of the ALU?(3)

Answer 8

Arithmetic operations - addition, subtraction, multiplication and division.
Logical operations - these include AND, OR and NOT.
Shift operations - The bits in a computer word can be shifted left or right by a certain number of places.

Question 9

What is the function of the CU?(4)

Answer 9

Controls the execution of instructions in the correct sequence
Decodes instructions
Regulates and controls processor timing using regular pulses from the system clock
Sends and receives control signals to and from other devices within the computer.

Question 10

What is the function of the Clock?(3)

Answer 10

Responsible for timing in the CPU
Switches off and on billions of times a second
Clock frequency is number of clock cycles per second.

Question 11

What is the function of the Registers?(3)

Answer 11

The Registers are very fast storage elements present in a very small amount in the computer processor, they contain the data that the CPU is currently processing.
Very few in total(maybe 64), some have very general purposes while others more specific.

Question 12

What are the functions of the buses?(3)

Answer 12

The System Bus links the different parts of the CPU.
It is split into:
Address Bus(sends memory addresses)
Control Bus(sends and receives control instructions)
Data Bus(sends and receives data)

Question 13

What are the 3 main factors affecting CPU performance and why?(6)

Answer 13

The faster the clock speed the more FDE cycles the computer can perform per second. Typical speeds for a PC are between 2 and 4 GHz.

Reading from and writing to main memory is much slower than the speed at which the processor can work. The logical answer is to use faster memory technologies in the main memory, but this increases the price of the computer. There must be a compromise between speed and cost.
One way of improving the speed at less cost is to use small amount of faster memory called cache. This is an intermediary between the main physical RAM and the CPU.
The cache makes any data frequently used by the CPU available much more quickly; because the processor accesses the main memory less often it can work faster and so CPU performance increases.
Computers may have 8GB of RAM(main memory) but only 2MB of cache memory.

Number of processor cores - on the whole a PC with a multi-core processor, executing many tasks at the same time, will operate faster than a single core processor.

Question 14

State and explain the FDE cycle?(5)

Answer 14

(Fetch)
1. Next address to be fetched is grabbed from a register
2.That register is incremented by 1 for the next instruction
3. CPU fetches the instruction from memory at the address that was given in step 1
(Decode)
4. The CU decodes the instruction and decides what to do with it
(Execute)
5. Finally run instruction

Question 15

What is the ROM?(3)

Answer 15

The Read Only Memory is non-volatile and is very small (4-16MB). It only stores the bootstrap for the computer to start up the operating system.
Memory can only be read and not written to.

Question 16

What are the two types of main memory?(2)

Answer 16

The RAM and the ROM.
Main memory can be accessed directly by the CPU, but secondary storage can not.

Question 17

What are the differences between HDDs and SSDs?(6)

Answer 17

HDDs are much cheaper, 8TB for £120 while SSDs may be 4TB for £500.
HDDs have more read/writes and therefore are extremely reliable.
HDDs have a larger capacity, up to 15-16TB while SSDs up to 4TB.
SSDs have a faster access speed on average, 6GB/s compared to HDDs 3GBs.
SSD(Flash Storage Devices) such as USBs and Memory Cards, are much more portable than huge portable Hard Disks.
HHDs are sensitive to shaking while SSDs are very robust.
HHDs may also be susceptible to magnetic fields.

Question 18

Define cloud storage?(2)

Answer 18

Cloud storage is the saving of data in an off-site storage system maintained by a third party, such as Dropbox, Google or Microsoft.
Instead of saving data on your computer’s hard driver or other local storage device, it is saved in a remote storage facility into either magnetic and/or solid state storage and accessed via the internet.

Question 19

What are the advantages and disadvantages of using cloud storage?(6)

Answer 19

System is maintained by a third party
Data and software is accessible from any location on multiple devices.
Data can be shared with others
Data is automatically backed up and kept safe
Dependent on a good reliable internet connection to access your data
Security concerns about preventing others without permission from accessing your data

Question 20

What are the two main types of software?(4)

Answer 20

System software - Programs that are needed to enable the computer to function, like the operating system or library routines.
Application software - Programs that enable a user to perform a task: eg word processing software, spreadsheets, databases, mobile phone ‘Apps’ etc.

Question 21

How is processor management dealt with by operating systems?(3)

Answer 21

In processing management each task is allocated processor time.
Processor time is shared between applications so that they appear to be running simultaneously but in reality are not running at the same time.
In a multi-core computer the operating system allocates tasks to each core where possible.

Question 22

How is memory management dealt with by operating systems?(3)

Answer 22

When a program is running it must be in the computer’s main memory, and the operating system must manage where in memory each program and where the data it needs will go.
Most computers are capable of holding several programs in memory at the same time(so that a user can switch between applications).
When the user starts up a program, the memory manager allocates it adequate blocks of free space in main memory. it also allocates memory for any data file that you open such as the essay you are working on in word.

Question 23

How are input/output devices dealt with by operating systems?

Answer 23

Input devices take real world data and convert it into a form that can be stored on the computer. These real world inputs are then processed by the computer system and generate real world outputs.
The input device, could be a mouse or keyboard and the output device could be a computer monitor or speaker that produces sound.
Each input or output device also has its own device driver which acts as an interface between the computer and the device. The operating system will make sure the correct driver is installed so that the computer can communicate with the printer.

Question 24

How are Applications dealt with by operating systems?(3)

Answer 24

Application programs need an operating system to function and to be installed. The user can also choose to install software, or move it into different folders - which is acted upon accordingly by the operating system.
An Applications Program Interface(API) allows the application to communicate with the operating system, and is how the OS communicates with applications; to execute modules, save or delete data etc.
The OS maintains a directory of where each application and each data file is stored on disk. When an application is run, the OS will allocate space in memory for it to be loaded and the job will enter the queue of jobs being allocated processor time.

Question 25

How is security dealt with by operating systems?(4)

Answer 25

Controls access to a computer by setting up passwords for different users, without knowing the password someone else will not be able to access the software applications and files on your computer. Setting different access rights and privileges for different users. Automatically downloading updates for the OS(updating itself) to ensure security loopholes are patched. Encrypting files that are stored on the hard disk.

Question 26

What is utility software?(2)

Answer 26

Software provided by the operating system that is not essential for the computer, but simplifies managing the tasks of operating system. These include: Security utilities to keep data safe, disk organisation utilities, data compression utilities, file backup utilities.

Question 27

Function of Encryption software?(2)

Answer 27

Encryption tools can help to keep sensitive data safe from cyber criminals or unauthorised access. They also protect backup copier of data kept on offline storage. It runs an encryption algorithm across data to change plain text to ciper text rendering it unreadable if intercepted. To decode the original information, one would have to know both the algorithm and the key.

Question 28

Function of the two Maintenance Utilities?(4)

Answer 28

Disk defragmentation. This moves separate parts of defragmented files around so they can be stored together in the secondary storage, which makes them quicker to access. It also groups all the free disk space together so that new files can be stored in one place - optimises disk performance, but only on HDDs. Automatic updating. This makes sure that any software installed on the computer is up-to-date. For any software already installed on the computer, the automatic update utility will regularly check the Internet for updates which will be downloaded instantly if need be. Firewalls, antivirus software and application software must all be updated regularly as new bug fixes and improvements become available.

Question 29

Function of Compression software?(2)

Answer 29

There are two types of compression, lossy and lossless. Compression software such as WInZin will reduce the size of a file in either one of these ways. Compressed or zipped files can be transmitted much more quickly over the Internet. Also there is sometimes a limit to the size of a file which can be transmitted, in this scenario compressing the file may allow it to be sent.

Question 30

What are characteristics of an embedded system?(4)

Answer 30

Performs one or a very limited number of tasks that is rarely changed/upgraded. The system is held in non volatile memory such as ROM or EPROM and is rarely ever changed Can’t be easily upgraded or extended. Can’t be easily customised outside of some basic configuration.

Question 31

Describe the Von Neumann computer design?(3)

Answer 31

John Von Neumann developed the concept of the stored program computer in the 1940s. The program is stored in main memory and instructions are fetched and executed sequentially. There is a single memory for accessing both data and programs.

Question 32

What are the three types of Optical media?(3)

Answer 32

CD, DVD and Blu-ray. CD has the least access speed and capacity, while Blu-ray has the greatest access speed and capacity. The price also goes accordingly. They are all very easy to carry in a bag or pocket, but can be corrupted or damaged easily by excessive sunlight or scratches.

Question 33

Explain how HDDs work?(3)

Answer 33

Magnetic disks are read with a moving head inside the disk drive. It uses rigid rotating platters coated with magnetic material. Ferrous(iron) particles on the disk are polarised to become either a north(0) or south(1) state. The disk is divided into tracks in concentric circles and each track is subdivided into sectors. The disk then spins very quickly at speeds of up to 10,000 RPM. A driver head moves across the disk to access different tracks and sectors. Data is read or written to the disk as it passes under the driver head. Hard Disk Drives usually consist of several platters, each with its own driver head. These drive heads are parked to one side of the disk in order to prevent damage from movement when not in use.

Question 34

Explain how SSDs work?(2)

Answer 34

SSDs are often referred to as flash memory/storage but their access speeds to not reach that of RAM. Solid state technology is used in memory sticks and memory cards and is also commonly found in laptops. Solid state devices are built from special types of transistors that do not lose their state when the power is switched off. There are two types of flash memory, NOR and NAND, wired in parallel and series respectively. Both types of SSD use electrical circuits to persistently store data.

Question 35

Explain how Optical disks work?(3)

Answer 35

There are very small 'pits' and 'lands' engraved onto an Optical disk. A low powered laser is bounced onto the surface and where there is a change of pit to land or vice versa it represents a 1. Everything else is a 0. This is because at the point of conversion light is scattered and does not reflect very well. There is also only a single track on an optical disk but it is arranged in a tight spiral.

Question 36

What is a high-level language and what are the advantages of using one?(4)

Answer 36

High-level languages are languages such as Python, C, C++, JavaScript, HTML. These can be written and used on any computer regardless of its architecture. However, it does require a compiler or interpreter to translate the code into machine code. High-Level languages are easier to write and interpret because they are more human-like. In this same light, they are also easier to debug.

Question 37

What is Assembly language and what are the advantages of using it?(4)

Answer 37

Assembly code is translated into an assembly, one statement translates into one machine code instruction. Their instructions may look like this: LDA #34 Assembly language is often used in embedded systems such as the computer systems that control a washing machine. It gives the programmer complete control over the system components so it can be used to control and manipulate specific hardware components. Very efficient code can also be written for a particular type of processor so it will occupy less memory and execute faster than a compiled high level language code.

Question 38

What is Machine code and what are the advantages of using it?(3)

Answer 38

Machine code is the code executed by the processor and consists only of 0s and 1s. Each type of processor has its own machine code instruction set and all programs whether written in a high-level language or in assembly language have to be translated into machine code before they can be executed.

Question 39

What is an Assembler?(3)

Answer 39

An assembler converts assembly language into machine code, which is a simple conversion as in general every assembly language instruction is translated into a single machine code instruction. Each different processor usually uses a different assembly language and a different assembler. For many architectures there is a wide choice of assemblers as some assemblers can assemble code for different processor architectures.

Question 40

What is a Compiler?(4)

Answer 40

A compiler translates a high-level language into machine code. This is a more complex translation than what is undergone by an Assembler, as a single instruction can result in many machine code instructions. A program written and complied on one type of computer would have to be compiled again to run on a computer with a different type of processor. The code written by the programmer is known as source code, and the machine code produced by the compiler is called object code. When a user buys commercial software, they are buying the object code and therefore do not need a compiler to run the software. For a developer this has the advantage in that someone buying the software cannot see or copy the source code.

Question 41

What is an Interpreter?(4)

Answer 41

An interpreter translates high-level language into machine code, but executes the program directly, translating each statement into a sequence of calls to one or more subroutines already complied into machine code. There must be an interpreter installed on the computer to run the software. Long and complex programs take much longer to execute if it is being 'interpreted'. A loop performed 10,000 times will have 10,000 lines to translate in the eyes of the interpreter. Java is compiled into an intermediate stage called byte code, which can be interpreted and run on many different types of processor using an appropriate byte code interpreter.

Question 42

Compare Interpreters and Compilers.(5)

Answer 42

Compiler translates whole program to produce (.exe) the executable object code. An interpreter translates and executes one line at a time. Compiled program executes faster because it is already in machine code. Interpreted programs take more time to execute because each instruction is translated before it is executed. Customers do not need to have the compiler installed on their computer to run the software. Customers must have the interpreter installed. Customers cannot see the actual source code when a compiled program is distributed. Customers can see the source code with interpreters and could copy it. Compiler is used for software that will be run frequently or copyright software sold to a third party. Interpreter is used for program development and when programs must be able to run on multiple hardware platforms.

Question 43

Describe an AND gate?(2)

Answer 43

Represented by a single small dot in Boolean expression. 0 0 0 1 0 0 0 1 0 1 1 1

Question 44

Describe an OR gate?(2)

Answer 44

Represented by a single plus sign in Boolean expression. 0 0 0 1 0 1 0 1 1 1 1 1

Question 45

Describe an XOR gate?(2)

Answer 45

Represented by a plus sign with a circle around it in Boolean expression. 0 0 0 1 0 1 0 1 1 1 1 0