MOCK REVISION 16th of June 2021

Question 1

What is the waterfall lifecycle model and when is it used? - in addition mention drawbacks/advantages

Answer 1

In the waterfall model every step is completed one at a time from beginning to end. Each step has specific outputs that lead into the next step. The user / customer is involved at the start of the process and in the analysis but has little input until the evaluation. It is suitable for small projects - but the absence of user involvement is a serious drawback . It is possible to return to a previous stage but the model shows that the developers then have to work back down the following stages.

Question 2

What is the Spiral model and when is it used? - in addition mention drawbacks/advantages

Answer 2

The spiral model uses the same structured steps (analysis design implantation evaluation). However it introduces the idea of developing the software in iterative stages. Each loop creates a prototype. Advantage: More user involvement and it is much easier to examine a working prototype to figure what needs to be done to turn it in a working system.

Question 3

What is Agile modelling and when is it used? - in addition mention drawbacks/advantages

Answer 3

Stages of software development may not be completed in a linear sequence. Some parts of the analysis might not be completed while some parts are implemented. This is a NON-LINEAR APPROACH. Prototypes are built to make sure that the project is in line with user requirements. It’s success depends on - Keeping the model simple
Rapid feedback from user
Understanding that user requirements may change
Being prepared for incremental changes.

Question 4

Explain the Fetch decode execute cycle (treat this as a 6 mark question)

Answer 4

Fetch: Contents of Program Counter / PC are transferred to Memory Address Register / MAR
the address bus is used to transfer this address to main memory
The transfer of content uses the data bus
Contents of addressed memory location loaded into the Memory Data Register /
MDR
Increment (contents of) Program Counter / PC A. at any part of fetch process
after transferring PC to MAR
Increment Program Counter / PC and fetch simultaneously
Contents of MDR copied to CIR
Decode:
Decode instruction held by the (Current) Instruction Register / (C)IR
The control unit decodes the instruction
Instruction split into opcode and operand
Execute:
If necessary, data is fetched
If necessary, data is stored in memory
The opcode identifies the type of operation/instruction to be performed (by the
processor)
Result (may be) stored in register/accumulator
The operation (identified by the opcode) is performed by the processor. A. ALU
Status register updated
If jump / branch required Program Counter/PC is updated
Remember this for full marks in ANY FDE question

Question 5

What is a LAN? - in addition mention drawbacks and advantages

Answer 5

A local area network is a computer network that interconnects computers within a limited area. Some advantages of LAN are Resource Sharing, Software Sharing, Improved Security and Centralized date.
Some disadvantages are Implementation Cost, Maintenance, Malware Spreading and Area Coverage.

Question 6

What is a WAN? - in addition mention drawbacks and advantages

Answer 6

A wide area network is a telecommunications network that extends over a large geographic area for the primary purpose of computer networking.
Advantages -
Boosts your privacy
Increases bandwidth
Disadvantage -
Maintenance Issues of the main data center
Security issues.

Question 7

What is a standalone machine?

Answer 7

A standalone machine is a piece of hardware that can work independently. This can be machines such as fax machines.

Question 8

What are the advantages of LAN over a standalone machines

Answer 8

In a LAN files can be easily shared and transferred from one computer to another. Moreover, the security is better than on standalone because files are not visible to other users other than the initial ones. Another benefit of LAN is that data is easy to backup as all data is stored in the file server. If a computer fails, the system will be ok as they are connected to a central server.

Question 9

State all registers in the CPU and what they do.

Answer 9

Current Instruction Register(CIR)- The register that stores the instruction that is currently being executed

Program Counter(PC)- The register that holds the address of the next instruction to be executed.

Memory Address Register(MAR)- The register that stores the address of the date, or the address of where the data will be sent to

Memory Data Register(MDR)- The register that holds the data being transferred to and from the immediate memory

Accumulator(ACC)- The register which holds an intermediate value in mathematical and logical calculations. This is all for a very short amount of time

Question 10

What is a data bus and what does it do? (treat this as a high mark question and go into detail)

Answer 10

The data bus is one of the three buses of the system. The data bus takes data to/from the memory to/from the CPU. This bus is bidirectional, which means that data is able to travel both ways. The amount of data a data bus is able to transfer at once is called bandwidth. Typical bandwidths are 32 bits, with newer computers being able to handle 64-bit and 96-bit data paths. This means that up to 96 bits of data can travel through a data bus every second.

Question 11

What is a control bus and what does it do? (treat this as a high mark question and go into detail)

Answer 11

The control bus is one of the three busses of the system.
The control bus controls most of the system. It gives commands to the system and hardware of the computer. These commands are:
Read - A single line that when active (logic zero) indicates the device is being read by the CPU
Write - A single line that when active (logic zero) indicates the device is being written by the CPU
Byte enable - A group of lines that indicate the size of the data (8, 16, 32, 64 bytes)
Transfer ACK - Delivers information that the data was acknowledged (read) by the device
Bus request - Indicates a device is requesting the use of the (data) bus
Bus grant - Indicates the CPU has granted access to the bus
Interrupt request - A device with lower priority is requesting access to the CPU
Clock signal - The signal on this line is used to synchronize data between the CPU and a device
Reset - If this line is active, the CPU will perform a hard reboot

Question 12

What is an address bus and what does it do? (treat this as a high mark question and go into detail)

Answer 12

An address bus is a computer bus architecture used to transfer data between devices that are identified by the hardware address of the physical memory (the physical address), which is stored in the form of binary numbers to enable the data bus to access memory storage

Question 13

What is an input device?

Answer 13

Input devices are external hardware that provide signals and data to a computer.They allow humans to interact with a computer.Examples of such devices are keyboards and mice

Question 14

What is an output device?

Answer 14

A device that allows data to be transmitted by the computer in a human-friendly form. -Monitor, Printer, Speakers.

Question 15

What is the purpose of input/output devices?

Answer 15

To allow humans to interact with a computer, without the need of advanced technological knowledge.

Question 16

What is packet switching and why is it important?

Answer 16

Packet switching is the transfer of small pieces of data across various networks. It is important as these data chunks or “packets” allow for faster, more efficient data transfer as bigger files can be broken down into smaller packets of 512 bytes. Every packet is given its own distinct address.

Question 17

What is error checking and why is it important?

Answer 17

It is a mechanism implemented to check and detect errors in packets received through the network. This allows for the data to be transferred successfully without corruptions.

Question 18

What are advantages/disadvantages of Packet switching?

Answer 18

ADV- Big files can be broken down and transferred much quicker though the network. Small files don’t need to be broken down but still travel very quickly.
DIS-Files/packets can e corrupted during transfer, thus the whole file would not be received correctly.

Question 19

What is Circuit switching and what are its advantages/disadvantages?

Answer 19

Circuit switching is a connection-oriented network switching technique. Here, a dedicated route is established between the source and the destination and the entire message is transferred through it.
ADV- Fixed data transfer rate and fixed bandwidth.
Increased quality of communication.
DIS-Channel resources not used fully, long time to establish connection, Requires more bandwidth.

Question 20

List all facilities of an operating system and what they do (treat this as a high mark question and go into detail)

Answer 20

Facilities:

User Interface - Puts computer language into text, images or other languages for humans to interact with.
Examples: 
Command line interface
Batch based interface
Graphical User Interface

Program Execution - Loads a program into memory and runs that program, also must be able to end execution.

File system manipulation - Programs need to be read and written as files and directories. Also allows users to create, load, move, read, edit or filter files.

Input / Output Operations - A program may require I/O, which may involve a file or other I/O devices. Users cannot directly govern the I/O devices. So, the OS provide a means to do I/O Input / Output operation which means read or write operation with any file.

Communication - Processes need to swap over information with other processes. Processes executing on same computer system or on different computer systems can communicate using operating system support. Done using shared memory or via message passing.

Resource Allocation - When multiple jobs are running at the same time, the OS needs to allocate resources to all of them. Resources can be CPU cycles, main memory storage, file storage and I/O devices.

Error Detection - Errors may occur within CPU, memory hardware, I/O devices and in the user program. For each type of error, the OS takes adequate action for ensuring correct and consistent computing.

Accounting - Keeps track of which users are using how much and what kinds of computer resources have been used for accounting or simply to accumulate usage statistics.

Security and protection - Ensuring all access to system resources in a controlled manner. For making a system secure, the user needs to authenticate him or her to the system before using.

Question 21

What is ROM and how is it used?

Answer 21

ROM is a form of non-volatile memory that can only be read from, it stores necessary startup operations/ bootstrap protocols that allow the computer to startup.

Question 22

What is RAM and how is it used?

Answer 22

RAM is a form of volatile memory that stores program operations that are currently active, information stored in RAM is faster to retrieve than from storage, as RAM is closer and faster than traditional storage devices. This makes the entire system more efficient as information can be forwarded to the CPU faster.

Question 23

What are the traits of RAM and why is it useful?(Miss Sheikh put it that way not me)

Answer 23

RAM is extremely fast allowing it to communicate with the CPU more quickly and reduce the time of the Fetch-Execute Cycle. This reduction means the computer is able to run more quickly.

Question 24

What are the traits of ROM and why is it useful?(Miss Sheikh put it that way not me)

Answer 24

ROM is non-volatile and cannot be written to, this makes it optimum for permeate storage of necessary startup protocols that should be unalterable, even in the case of hacking.

Question 25

What are all the assembly language notations?

Answer 25

ADD, SUB, DIV, MUL, LDA, STR, MOV, IF, LOOP, BRP (Branch if positive), BRA (Branch)

Question 26

How do you convert from denary to binary? (GCSE stuff)

Answer 26

You divide the initial value by 2, if the remainder is not equal to 0, then its value is 1. Repeat this with the new value(excluding the remainder value),8 times. Then put the binary values in reverse, that is the binary value.

Question 27

What is an IDE?

Answer 27

An IDE provides a platform for which program developers can use for software development. These usually consist of a source code editor, build automation tools as well as a debugger. (e.g. Pycharm, Visual Studio and Eclipse)

Question 28

What is a local variable?

Answer 28

This is a variable which is only accessible within a section of the program such as a subroutine.

Question 29

What are Parameters? (in computing)

Answer 29

Parameters allow for information/instructions to be passed into functions and procedures. They’re useful numerical information such as stating a file size.

Question 30

What are functions and why are they important?

Answer 30

An easy way to look at functions is to think of them as mini-programs. They allow for the main code to be written without having to deal with the function. This breaks the coding process into smaller chunks reducing the strain on the software developer.

Question 31

What is parameter passing and why is it important?

Answer 31

This allows for variables to be accessed as well as updated and used within sub-programs.

Question 32

What is pipelining how does it work and why is it useful?

Answer 32

Pipelining allows for the processor to start another process while the previous one is still being completed allowing for faster processing speeds therefore a higher clock speed.

Question 33

What is the TCP - IP protocol (include packet switching)

Answer 33

TCP - IP (Transmission Control Protocol - Internet Protocol) is the protocol for 2 computers to communicate with each other. When they do communicated data is sent in packets in the size of 512 bytes.
TCP-IP is a set of rules for communication over the internet.

Question 34

What are the advantages of having a CSS file outside of the HTML file instead of having it embedded?(treat this as a high band question)

Answer 34

External CSS files enable you to apply styles on a single CSS stylesheet to multiple HTML files throughout an entire website.

This also removes the CSS from the HTML pages, which makes them easier to read.

Question 35

What is an assembler?(go in detail)

Answer 35

An assembler is a program that takes basic computer instructions and converts them into a pattern of bits that the computer’s processor can use to perform its basic operations. Some people call these instructions assembler language and others use the term assembly language.

Question 36

What is extreme programming?

Answer 36

Extreme programming is a software development methodology which is intended to improve software quality and responsiveness to changing. It’s the most specific of the agile frameworks regarding appropriate engineering practices for software development.

Question 37

What are intrerrupts - when are they used and how are they useful?

Answer 37

An interrupt is a signal that is sent to the processor to request immediate attention. When the processor receives this request, it suspends what it is doing and runs the process associated with the interrupt.

The processor can be interrupted for a number of reasons, including:

• A hardware device has signaled that it has data to process
• A hardware device has completed a task that it was asked to do
• A software process needs a service to be provided or OS function to be performed
• An allotted amount of time has expired and an action needs to be performed
• A hardware failure has occurred and needs to be addressed

Question 38

What is implementation?

Answer 38

After the planning and design of a project the implementation part is when you write the code for it.

Question 39

What is sequence?

Answer 39

Sequence is basic code that only executes once unless defined twice and has not specific execute criteria. For example a print statement.

Question 40

What is iterration?

Answer 40

Iteration is a loop. An example of iteration would be an application running a continuous loop checking for inputs.

Question 41

What is selection?

Answer 41

Selection is code that only executes when a certain condition is met. For example an if statement.

Question 42

HTML extract - you will be asked to write a code for a piece of text or image

Answer 42

.

Question 43

SQL(3 marks)

Answer 43

https://www.codecademy.com/learn/learn-sql

Question 44

Scenario type question:

Answer 44

Question about inputs: Real-life situation - use common sense

Question 45

Assembly

Answer 45

There will be 2 assembly type questions unfortunately there is no way we can help each other with that besides learning the notations. Sorry…

Question 46

A Little Man Computer (LMC) assembly language program is stored in memory as shown in Fig. 3.1.
      0      LDA &7
      1       ADD #4
      2      OUT
      3      HLT
      4      6
      5      2
      6      10
      7      15
      8     16
      9      17

In this variant of LMC, the symbols & and # are used to denote different modes of addressing.

Given that the output is 17, state the addressing mode represented by each symbol.

& _ _ _ _ _ _ _ _ _ _ _ _ _ [1]
# _ _ _ _ _ _ _ _ _ _ _ _ _ [1]

An assembler is used on the code.

Answer 46

i) & immediate addressing

ii) # indirect addressing