Graded unit

Question 1

Define RAM

Answer 1

Random access memory

It is volatile

Can be static or dynamic

Question 2

Define ROM

Answer 2

Read only memory

Memory is non volatile

PROM,EPROM, etc

Question 3

What are the advantages of using direct memory access for handling input/output transfers

Answer 3

It is used for transferring blocks of data

It speeds up the data transfer between RAM and peripherals

Bypasses the CPU for certain types of transfers allowing the cpu to carry out other tasks

Suitable for high speed devices

Question 4

Explain the following attribute setting - archive

Answer 4

A file with the attribute on which has not been backed up since it was last eddited or since it was created

Question 5

Explain the following attribute setting - read-only

Answer 5

A read-onky file cannot be edited or written to disk

Question 6

Explaine the following attribute setting - hidden

Answer 6

A file with this attribute on is not displayed within the default settings of the O/S

Question 7

Explain the following attribute setting - system

Answer 7

Is a designated system file and is normally not displayed in modern O/S

Question 8

Polling is a method which the computer system uses to share processing time. Explain it and give one advantage and disadvantage

Answer 8

Polling is a continuous method of checking other programs or devices by one program, or devices to establish its state usually to see if they are still connected or want to communicate

Advantage - even and fair share of processing time

Disadvantage - each device is checked in turn, one at a time, wether the device wants to communicate or not

Question 9

Interruptes are a method which the computer system uses to share processing time. Explain it and give one advantage and disadvantage

Answer 9

An interrupt is when a signal is recived from a device attached to a computer or from a program within the computer that causes the main program that operates the computer to stop and work out what to do next

Advantage - priority levels may be set

Disadvantage - it takes turns in which program or set of instructions that it preforms

Question 10

State the main function of DRAM and how it’s used in a computer system

Answer 10

DRAM loses its charge over a period of time. A value of 1 stored in this type of chip can be changed to 0 over time unless the chip is refreshed with a frequent charge. This type of memory is used as main memory and considered to be volatile with the contents being lost if the power is switched off

Question 11

State the main function of ROM and how its used in a computer system

Answer 11

ROM is read only memory and is non volatile, ROM does not lose ita contents if the power is switched off. ROM is used in a computer system to store part of the operating system. When the computer is switched on the programs contained in ROM are loaded into the computer system

Question 12

State the function of SRAM and how’s its used in a computer system

Answer 12

SRAM is a volatile memory and often used in cache or where fast ram is required unlike DRAM static RAM can only be changed in two ways, firstly, when the power is switched off, and secondly, when the value in a memory location is changed

Question 13

What is the purpose of the address bus

Answer 13

This carries the address of the area in memory that is too be accessed

Question 14

What is the purpose of the control bus

Answer 14

This carries the signal concerning timings of memory read, write and device I/O

Question 15

What is the purpose of the data bus

Answer 15

This carries the data to be transfered or manipulated by the CPU

Question 16

what is the function of ROM and how is it used within a computer system

Answer 16

Bootstrap (ROM) – use to store part of operating system or boot sequence. Small amount of Read only memory, permanent, cannot be changed.

Question 17

what is the function of SRAM and how is it used within a computer system

Answer 17

Cache (SRAM) – stores regularly used data, instructions, variables used in executing programs, speeds up data transfer to CPU. Faster to access than data stored in main memory or virtual memory. Always accessible as no need to refresh.

Question 18

what is the function of DRAM and how is it used in a computer system

Answer 18

Main memory (DRAM) – Large amount of memory stores application packages and files currently in use by CPU. Faster to access than Virtual Memory but slower than SRAM. Cannot be accessed while being refreshed.

Question 19

Explain the role of cache memory in enhancing the performance of the CPU.

Answer 19

Fast memory blocks quicker than DRAM.

Small amount of SRAM

Used to store variables used in programming no need to keep updating slow DRAM.

Faster memory used to transfer data between CPU.

Or any other reasonable answer

Question 20

Backup is an essential task if you are not to lose information. State three different types of backup

Answer 20

Full backup

Incremental backup

Differential backup

Question 21

what is the effect on the archive attribute for a full back up

Answer 21

Backup of all files and folders on the system

Consists of data and configuration files

Regular basis but least frequent of the backups

Carried out prior to any major system changes

May be required for restoration purposes along with incremental backups

Unlikely to include software applications

Any other reasonable answer

Question 22

what is the effect for the archive attribute for a incremental back up

Answer 22

Used on a regular basis eg daily

Faster than full backup, used for day to day data backups

Operational back up of selected data

Backs up only files and folders that have changed since last incremental backup

restoration requires both last full backup and the incremental backups

Archive bit is reset for each file backed up

Question 23

what is the effect for an archive attribute for a differential backup

Answer 23

Used on a regular basis eg daily

Faster than full backup but slower than incremental

Operational back up of selected data

Backs up files and folders that have changed since last full backup regardless of whether they were backed up in the last differential backup

Each backup supersedes all previous backups

restoration requires only the final differential backup

does not reset the archive bit

Question 24

describe the following type of a multi user system - networked system

Answer 24

Sharing of resources over a number of computers

Use of a server provides network services such as logon and security

Centralised data storage accessible by permissions

May mention physical aspects (LAN, NICs etc)

Question 25

describe the following type of a multi user system - multi-tasking system

Answer 25

Computer appears to be carrying out tasks simultaneously May describe either pre-emptive of co-operative multi tasking systems

Question 26

A computer operating system can be broken down into a number of discrete layers, or functional elements, each of which is responsible for a specific task, describe the following functional layer - kernel

Answer 26

The low level interaction between the operating system and the computer hardware An interrupt handler that determines the CPU handling of I/O requests A scheduler that determines which programs share processing time and in which order A supervisor that gives use of the CPU to each process when it is scheduled The kernel services can be requested by other parts of the O/S or by application programs via system calls

Question 27

A computer operating system can be broken down into a number of discrete layers, or functional elements, each of which is responsible for a specific task, describe the following functional layer - file management

Answer 27

Provides a user interface to work with file systems. Keeps track of file locations on disk, including location of fragmented files Supports the most common operations on files are create, open, edit, view, print, play, rename, move, copy, delete, attributes, properties, search/find, and permissions.

Question 28

Describe the operation of virtual memory

Answer 28

Used to spread the load of physical RAM Portion of hard disk set aside and used as a swap file Virtual memory is created on backing storage and matches the physical memory available i.e. 4GB RAM has 4GB virtual memory created on disk. Virtual memory is usually created dynamically during the loading of the OS Uses a paged addressing system Any other reasonable answer

Question 29

Explain the advantages of using the Direct Memory Access (DMA) technique for handling input/output transfers.

Answer 29

is used for transferring large blocks of data between peripheral devices and memory. speeds up data transfer between RAM and peripherals. bypasses the CPU for certain types of transfer, allowing the CPU to carry out other tasks. On completion of transfer, DMA controller informs CPU. suitable for high-speed devices. Efficiency of the CPU is increased as CPU can continue to process while the transfer is taking place.

Question 30

Define the term ‘cycle stealing’ in the content of DMA explaining priority.

Answer 30

When both the CPU and the DMA controller wish to access memory at precisely the same time. Priority usually given to the DMA because the transfer of data from very fast peripheral devices attached to the DMA cannot be held up. This is known as cycle stealing.

Question 31

Explain two functions of each of the following components of an operating system – file management

Answer 31

Creates the link between the logical file and the directory structure Handles the allocation of space to files and their allocated space Handles the linkage between areas of non-contiguous storage

Question 32

Explain two functions of each of the following components of an operating system – memory management

Answer 32

Allows several programs to run simultaneously Controls the allocation of memory to programs The mapping between virtual and real memory

Question 33

Explain two functions of each of the following components of an operating system – input/output

Answer 33

Communication between hardware peripherals and system components Communicating with the File Management re location of files

Question 34

A file can have different attribute settings. Define this term

Answer 34

In an operating system, file properties, such as "read-only" or "hidden," are called file attributes. These attributes which are tagged to a file and can be changed by a user to modify the status of a file.

Question 35

Describe the term “device driver” providing an example.

Answer 35

Description — A device driver is a piece of software that provides communication between the Operating System and the device, and operation of the device attached to the computer. Examples: Printer drivers, sound cards, video cards, graphics cards etc.

Question 36

Describe the term ‘thrashing’ in relation to virtual memory.

Answer 36

Virtual memory uses a swap file on hard disk as extended memory. Used when insufficient amount of RAM for processes required by CPU Content of virtual memory needs to be loaded back into main memory for use by CPU. This may require processes from main memory to be swapped out to virtual memory to make space in main memory. ‘Thrashing’ occurs when the system is constantly swapping programs and processes from main memory and virtual memory.

Question 37

Computer programs make use of a variety of different data types. Describe two different data types and examples of when they would be used

Answer 37

Integer – whole numbers Char – single character String – group of characters / array of chars Float / double – floating point/real numbers Boolean – true false

Question 38

Data types can either be declared as constants or as variables. Describe each of the following - constants

Answer 38

A data item with a fixed value which does not change during execution Generally global scope

Question 39

Data types can either be declared as constants or as variables. Describe each of the following - local variables

Answer 39

Local variable only has scope within the function/module/ method/etc within which it is defined. Passed throughout the program by use of parameters Considered good practice

Question 40

Data types can either be declared as constants or as variables. Describe each of the following - global variables

Answer 40

Global variable has scope throughout the complete program. Avoid use as this memory is set up at the beginning but may not be required

Question 41

When writing code for any problems there are a number of good programming practices that should be adopted to ensure that in the future code is easily maintained. Outline the good practices that lead to well maintainable code.

Answer 41

Follow statement of standards for best practice Use of comments throughout Indentation Use of modular code Appropriate use of variables – local and parameter passing – avoid global Meaningful names throughout variables and methods Appropriate lay out and use of whitespace

Question 42

In a project which you have carried out describe, with examples, the use of inbuilt functions

Answer 42

Inbuilt Functions:, We might need to work with dates and times. We can use inbuilt functions from Python's datetime module for this purpose.

Question 43

In a project which you have carried out describe, with examples, the use of functions that you wrote yourself.

Answer 43

Custom Functions: We may need to perform specific operations related to our task that aren't covered by inbuilt functions. For example, we might want to calculate the average mark for a pre-set number of students. We can write a custom function for this

Question 44

In functions defined by the programmer data is often passed between functions in the form of parameters. Give a description of the use of the type of parameter listed below - passing by value

Answer 44

Actual value passed Value does not alter in any way Eg student grade passed to calculate average – grade does not change

Question 45

In functions defined by the programmer data is often passed between functions in the form of parameters. Give a description of the use of the type of parameter listed below - passing by value

Answer 45

Uses address of operator (&) Address of variable passed Value will be altered in some way and new value stored in the address and passed back to calling routine Eg student average grade – calculated average

Question 46

A program is written that calculates the average grade based on three individual scores. Each of the three scores is passed for calculation of the average which is then calculated and passed back to the calling functions. Identify, for the three individual grades and the average, what is passed by reference and what is passed by value giving a brief reason why. ## Footnote what is value and what is refrence for actual grades and average

Answer 46

Actual grades passed as value. They will not change Average passed as reference will be used to store result of calculation and passed back

Question 47

Before software is handed over to the client it must be tested. Testing is a very important stage in the software development process and as such there are a vast range of tests that require to be carried out. Describe, with reasons, the test strategy that you followed in the Developing Software Introduction unit.

Answer 47

Any acceptable and justified answered but the following is expected Test strategy - white box bottom up approach Given test logs with test data and expected results Carried out by the programmer Results of testing documented Retested where necessary

Question 48

You were provided with, and made use of, a given test plan. Describe what you would normally expect to find in a test plan.

Answer 48

Module to be tested Reasons for test Test data Expected result

Question 49

You would expect to test a system using data that would produce normal test conditions. Describe what other types of test you would carry out and give one example

Answer 49

Boundary tests upper or lower limits Extreme Tests data of correct type that would not be within normal range Exceptional Data of a different type will throw an exception and crash program

Question 50

When referring to Troubleshooting what is meant by the term Half – Split?

Answer 50

Divide and conquer method for finding a fault. Applying previous knowledge and attempting to solve a problem at a set level.

Question 51

When troubleshooting what type of fault-finding tools are commonly used to assist with fault diagnosis?

Answer 51

Flowcharts, Company Faults database, Internet, previous experience

Question 52

What is the purpose of Preventative Support on a computer system

Answer 52

The purpose of preventative support on a computer system is to proactively identify and address potential issues before they escalate into problems that can disrupt operations or cause downtime. By implementing preventative support measures, organizations can minimize the risk of system failures, optimize performance, and enhance overall reliability

Question 53

Why is documentation very important when completing the troubleshooting process?

Answer 53

It provides a record of all the steps taken during troubleshooting. This record helps in tracking what has been done, what worked, and what didn't. Without documentation, it's easy to forget steps or repeat them unnecessarily. Documentation allows for knowledge sharing among team members. If multiple people are involved in troubleshooting a problem, documentation ensures that everyone is on the same page regarding the current state of the issue and the steps taken so far. Well-documented troubleshooting processes serve as a valuable reference for similar issues in the future. If a similar problem occurs again, the documentation can be revisited to see how it was resolved previously, saving time and effort. Detailed documentation aids in conducting root cause analysis. By documenting the symptoms, tests conducted, and solutions attempted, it becomes easier to identify patterns and underlying causes of recurring issues. In some industries, documentation is essential for auditing and compliance purposes. Properly documented troubleshooting processes demonstrate that proper procedures were followed and can be crucial for regulatory compliance. Documentation can be used for training new team members or for refreshing the knowledge of existing ones. A well-documented troubleshooting process serves as a guide for understanding how to approach and resolve similar issues in the future.