Graded unit Flashcards
Define RAM
Random access memory
It is volatile
Can be static or dynamic
Define ROM
Read only memory
Memory is non volatile
PROM,EPROM, etc
What are the advantages of using direct memory access for handling input/output transfers
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
Explain the following attribute setting - archive
A file with the attribute on which has not been backed up since it was last eddited or since it was created
Explain the following attribute setting - read-only
A read-onky file cannot be edited or written to disk
Explaine the following attribute setting - hidden
A file with this attribute on is not displayed within the default settings of the O/S
Explain the following attribute setting - system
Is a designated system file and is normally not displayed in modern O/S
Polling is a method which the computer system uses to share processing time. Explain it and give one advantage and disadvantage
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
Interruptes are a method which the computer system uses to share processing time. Explain it and give one advantage and disadvantage
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
State the main function of DRAM and how it’s used in a computer system
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
State the main function of ROM and how its used in a computer system
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
State the function of SRAM and how’s its used in a computer system
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
What is the purpose of the address bus
This carries the address of the area in memory that is too be accessed
What is the purpose of the control bus
This carries the signal concerning timings of memory read, write and device I/O
What is the purpose of the data bus
This carries the data to be transfered or manipulated by the CPU
what is the function of ROM and how is it used within a computer system
Bootstrap (ROM) – use to store part of operating system or boot sequence. Small amount of Read only memory, permanent, cannot be changed.
what is the function of SRAM and how is it used within a computer system
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.
what is the function of DRAM and how is it used in a computer system
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.
Explain the role of cache memory in enhancing the performance of the CPU.
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
Backup is an essential task if you are not to lose information. State three different types of backup
Full backup
Incremental backup
Differential backup
what is the effect on the archive attribute for a full back up
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
what is the effect for the archive attribute for a incremental back up
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
what is the effect for an archive attribute for a differential backup
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
describe the following type of a multi user system - networked system
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)
describe the following type of a multi user system - multi-tasking system
Computer appears to be carrying out tasks simultaneously
May describe either pre-emptive of co-operative multi tasking systems
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
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
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
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.
Describe the operation of virtual memory
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
Explain the advantages of using the Direct Memory Access (DMA) technique for handling input/output transfers.
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.
Define the term ‘cycle stealing’ in the content of DMA explaining priority.
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.
Explain two functions of each of the following components of an operating system – file management
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
Explain two functions of each of the following components of an operating system – memory management
Allows several programs to run simultaneously
Controls the allocation of memory to programs
The mapping between virtual and real memory
Explain two functions of each of the following components of an operating system – input/output
Communication between hardware peripherals and system components
Communicating with the File Management re location of files
A file can have different attribute settings. Define this term
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.
Describe the term “device driver” providing an example.
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.
Describe the term ‘thrashing’ in relation to virtual memory.
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.
Computer programs make use of a variety of different data types. Describe two different data types and examples of when they would be used
Integer – whole numbers
Char – single character
String – group of characters / array of chars
Float / double – floating point/real numbers
Boolean – true false
Data types can either be declared as constants or as variables. Describe each of the following - constants
A data item with a fixed value which does not change during execution
Generally global scope
Data types can either be declared as constants or as variables. Describe each of the following - local variables
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
Data types can either be declared as constants or as variables. Describe each of the following - global variables
Global variable has scope throughout the complete program.
Avoid use as this memory is set up at the beginning but may not be required
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.
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
In a project which you have carried out describe, with examples, the use of inbuilt functions
Inbuilt Functions:, We might need to work with dates and times. We can use inbuilt functions from Python’s datetime module for this purpose.
In a project which you have carried out describe, with examples, the use of functions that you wrote yourself.
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
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
Actual value passed
Value does not alter in any way
Eg student grade passed to calculate average – grade does not change
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
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
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.
what is value and what is refrence for actual grades and average
Actual grades passed as value. They will not change
Average passed as reference will be used to store result of calculation and passed back
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.
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
You were provided with, and made use of, a given test plan. Describe what you would normally expect to find in a test plan.
Module to be tested
Reasons for test
Test data
Expected result
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
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
When referring to Troubleshooting what is meant by the term Half – Split?
Divide and conquer method for finding a fault. Applying previous knowledge and attempting to solve a problem at a set level.
When troubleshooting what type of fault-finding tools are commonly used to assist with fault diagnosis?
Flowcharts, Company Faults database, Internet, previous experience
What is the purpose of Preventative Support on a computer system
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
Why is documentation very important when completing the troubleshooting process?
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.
