Define Delivery? Explain various delivery concepts or methods.

Delivery: 

Delivery refers to the way a packet is handled by the underlying network under the control of the network layer. Various delivery concepts are explained below.

Connection Types: 

Delivery of a packet in the network layer is accomplished by either a connection oriented service or a connection-less service.

What is connecting device? Describe various connecting devices.

Connecting Devices: 

Devices that are used to connect other devices are called connecting devices. That is, connecting device is a device that connects.

There are 4 types of connecting devices. They are as follows,

Describe CSMA/CA or Carrier Sense Multiple Access with Collision Avoidance.

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA):

This is a wireless network multiple access method defined by IEEE 802.11 standard. CSMA/CA is a modification to CSMA/CD. Collision detection as in CSMA/CD is not applicable for several reason, one reason is Hidden Terminal Problem.

Describe CSMA/CD or describe the access method of Ether LANs.

CSMA/CD (Carrier Sense Multiple Access with Collision Detection): 

The IEEE 802.3 defines the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) as the standard access method for traditional Ethernet. Stations in a traditional Ethernet can be connected using a physical bus or star topology, but the logical topology is always a bus. It means that the medium is shared and only one station can use it at a single time. But the problem is the assurance that only one station is using the medium at a time is solve d as follows,

Explain the Basic Structure of a C Program with an Example.

Basic structure of C programming: 

To write a C program, we first create functions and then put them together. A C program may contain one or more sections. They are illustrated below.

What is computer threat? Describe any 6 computer threats.

Computer Threats:

A threat, in general, is a person or a thing likely to cause damage or danger. In computer security, a computer threat is a possible danger that might exploit vulnerability to breach security and therefore cause possible harm. A computer threat is any activity that can cause damage to private or any data of an user or organization or any system in ways like removing, stealing, manipulating etc. This can be more summarized to unauthorized access to data of a system and causing damage to that.

What is malware? Describe any 5 types of computer malware with an example.

Malware

Malicious Software or Malware is any piece of software that disrupts computer operation, steal information, gain access to private systems or display unwanted advertising. Malware causes intentional harm, direct or indirect, to the computer by damaging files etc. or to the user by stealing sensitive information of the user from the computer etc. A software with bug causing unintentional harm is not a Malware. Malware are developed with targets which can be as simple as displaying ads to as serious as deleting or damaging files to stealing bank account or credit card information of the user.

What are the steps followed by CPU to Execute an Instruction?

CPU (Central Processing Unit):

CPU or central processing unit is an electronic circuitry that carries out the instruction given by a computer program. CPU execute instruction by performing basic arithmetic, logical, control and I/O operations as required per instruction. CPU is considered to be the brain of the computer. The speed and efficiency of a computer mostly depends that of it's CPU.

What is Motherboard? What are the role or functions of motherboard?

Motherboard:

A motherboard is a printed circuit board (PCB) that holds other modular devices, both required and additional, and facilitate communication among the devices to actually have the computer be functional.

Motherboard is like a backbone to a computer system. Components like CPU, RAM, Harddisks along with additional devices like TV Cards, graphics etc. all initially connects to the motherboard. The motherboard enables the devices by ensuring power supply to the device, transferring instruction from and to the device etc.

Define Instruction Set Architecture. What are the main objectives of ISA in computer systems.

Instruction Set Architecture (ISA):

An instruction set is the interface between a computer's software and its hardware, and thereby enables the independent development of these two computing realms. ISA is the set of basic instructions that a processor understands.

ISA includes functional definition of operations, modes, and storage locations supported by hardware and precise description of how to invoke, and access them.

Suggested Reading:
1. What are CISC (Complex Instruction Set Computer) & RISC (Reduced Instruction Set Computer)? What are the differences between CISC & RISC?

What are CISC & RISC? What are differences between CISC and RISC?

The instruction set or the instruction set architecture (ISA) is the set of basic instructions that a processor understands. The instruction set is a portion of what makes up an architecture.


Two initial types of instruction set architecture are CISC (Complex Instruction Set Computer) and RISC (Reduced Instruction Set Computer).


Explain Software Design & Implementation Activity

Software Design & Implementation Activity:

The implementation stage of software development is the process of converting a system specification into an executable system. A software design is a description of the structure of the software to be implemented, the data which is part of the system, the interfaces between system components and, sometimes, the algorithms used. Designers design step by step to meet the finished design to be implemented in programming to crease an executable system out of the specification.

Thus, output of each stage of the design process is the input of the next stage. Stages continue until a finished design is met which includes all the specification and work involved in the development of the software.

How to read and write INI files in PHP?

INI Files:

INI files are simple text files with a basic structure consisting of sections, property and value. INI files can be used across different platform which is a great advantage as a single INI file can be used in various versions of the same application for various platforms. INI files are used to store configurations for applications in a manner of property = value. Values can be single or one dimensional array. Also sections can be used to group same type of configurations. The last thing is comments, we can write comments in INI files. Comments in INI files starts with ; (semicolon)

How to Save PHP Array in Database in PHP

When we create management system or a CMS like application, we need to store a lot of configuration per user, per module etc. Multidimensional array is the best ever thing to work with in such situation. Configuration can be of two different types; searchable and not searchable. Searchable configurations are those which are used to filter a search result. For example various flags, tags, categories that we store with contents. We might need to filter contents with this flags, tags etc. No searchable configurations are like widget settings. We do not search for settings of an widget, rather we need those settings while rendering the widget.

How to read commented lines in a PHP file in PHP?

Did you ever noticed the commented lines over theme files, widget and plugin files in PHP in different CMS like wordpress etc.? These commented lines are not there just because the developer wanted to, these are most probably there as the system where the file will be used requires those lines to be there at the beginning of the file to describe the files in terms such as the name of the theme or plugin, created date, author name, last modified, version name etc. These information about the file then can later be used in the system or CMS.

This purpose can be solved in many ways, such as
  1. Using a .ini file
  2. Using a separate .php file that returns an array of information
  3. Using a array-string-array method
  4. Using .txt or any file with any or no extension
  5. Using a registration method

How to pass or use PHP array in Javascript variable?

Multidimensional PHP arrays are similar to multidimensional JSON objects. So shouldn't be there a way to use a multidimensional PHP array in Javascript? Obviously, and there is ways. For example you can use AJAX to make a request and get the PHP back in JSON format. However, why to make an AJAX call if the array is ready to be used already? Right.

If the PHP array is ready to be used in Javascript already, then just simply echo the PHP array in a Javascript variable as follows.

What is Software Specification Activity? Describe the four main phases of software specification activity?

Software Specification:

Software specification or requirements engineering is one of the four activities of software process. In software specification, the task is to identifying and defining the services to be provided from the system and what are the constraints in the operations of the system and in the development of the system. This stage, among the four activities of software process, is critical enough as this is the first stage of the process and defines the whole system. Missing or misunderstanding requirements, leaving gaps or errors will ultimately cause higher development cost, time and rework.

Describe the Waterfall Software Process Model

Waterfall Software Process Model:

Waterfall model software process model was derived from general system engineering process and it is so called as the stages go top to bottom and while one stage of the process is complete it moves to the next stage and not supposed to come back to any previous stage. That is one stage is supposed to be started if and only if the previous stage is finished and approved to move on to the next stage. However, in practice, things doesn't happen this way.

Following is an illustration of the involved stages of Waterfall model.

How To Add/Remove a Label To/From Multiple Posts at a Time in Blogger?

Dear blogger users, when we start blogging with blogger we misuse labels in blogger in blog posts. We generally forget that labels in blogger blog posts are like categories. Sometimes we might also not use meaningful labels to blog posts. Instead we use meaningless labels to our blog posts. Thus after a year, when we start learning more about categorizing blog posts with labels, we find hundreds of meaningless or misused or misspelled labels in our blog posts.

How to add adsense ads in the middle of the content in blogger template?

Middle of the Content is the best performing ad position for me so far among all the 5 Best Ad Positions I discussed earlier. This ad position is so effective as the reader sees the ad while reading your post and if you can blend the ad style with the style of the content then the reader will definitely click on it if the ad is relative to the content and valuable to the reader's interest.

I am going to discuss two ways, both ways required you to setup a bit of jQuery code in your template initially. Where the ways differ is that in the second way, you have to EDIT HTML of your content (post or page).

Both of the ways, require jQuery, those one with good JS understanding can implement this without jQuery.

What is control unit? What are the functions of control unit?

Control Unit:

Control unit co-ordinates the transfer of data between registers of CPU or microprocessor and ALU. Control unit serves the instructions for ALU. Along with this, control unit, as its name implies, controls every other parts of the machine, their co-ordinations, traffic etc.

Thus control unit controls the complete work-flow of the CPU. But control unit doesn't take inputs, give outputs, process data or store data itself, what control unit do is, it controls these operations when they are performed by respective devices.

Discuss the organization and functions of ALU or Arithmetic & Logic Unit

Arithmetic and Logic Unit (ALU):

Arithmetic and Logic Unit is a like a calculator to a computer. ALU performs all arithmetic operations along with decision making functions. In modern CPU or Microprocessors, there can be more than one integrated ALU to speed up arithmetical and logical operations, such as; integer unit, floating point unit etc.

What is Microprocessor? What are the functions of microprocessor?

Microprocessor:

A type of computer processors that incorporates the functions of a computer's center processing unit (CPU) onto a single integrated circuit is called a microprocessor. A microprocessor is a VLSI (Very Large Scale Integration) Silicon Chip. A microprocessor accepts digital or binary data, processes it according to instructions stored in it's memory and provides results as output.

Microprocessors are considered to be the brain of Microcomputers or Microprocessor based computer. Microprocessor contains both combinational logic and sequential digital logic.

What is CPU? What are the functions of CPU?

CPU (Central Processing Unit):

CPU or central processing unit is an electronic circuitry that carries out the instruction given by a computer program. CPU execute instruction by performing basic arithmetic, logical, control and I/O operations as required per instruction. CPU is considered to be the brain of the computer. The speed and efficiency of a computer mostly depends that of it's CPU.

How to add adsense ad code AFTER the CONTENT in blogger template?

After the content is one of the recommended ad positions I have already mentioned in the post 5 Best Ad Positions to Increase Adsense Revenue. In this post, we will see how we can add adsense ad code after the content of each post and page. We will do this in the blogger template so that we don't have to do this for each post and page.


How to add adsense ad code BEFORE the CONTENT in blogger template?

Before the content is one of the recommended ad positions I have already mentioned in the post 5 Best Ad Positions to Increase Adsense Revenue. In this post, we will see how we can add adsense ad code before the content of each post and page. We will do this in the blogger template so that we don't have to do this for each post and page.


How to find the data:post.body or post body in blogger template?

In blogger template, <data:post.body/> is the tag which prints out the full body of your post. This is important to know where this tag is to do things around post body. But the problem is, in some templates there can more than one <data:post.body/>. So how to find which one is the one that prints your post? Unfortunately there is only one way, debugging.

How to get variable value from URL query string in PHP?

We already know that we can get URL query string variable in $_GET super global array. But sometimes we might have to analyze a string which is an URL with query string and need to pull out value of a given variable from that. Also, it can be that we were given only the query part of an URL as string and we have to find out value of a given variable. Lets see how we can face this issue.

How to read the RAW version of POST data in PHP?

Well when you submit data using a form or anyway and the method is POST then you get the submitted data in a super global array called $_POST. But the data in the $_POST will be slightly modified by PHP that you sometimes, as per your requirement, may not be the exact same thing you inserted. But there is also another way you can access the data in $_POST without any modification, that is the RAW version.

Using Group Names in PHP preg_match() regex to index matched results by names instead of numeric values

Using regular expressions is a very effective way to find a sub-string or all matched sub-string from a given string or text. But when you call them they give you matched results in a array with numeric indexes which is not helpful enough to get your data out of the matched results. Following is the way to index matched results by name.

8 Easy Tips to Improve Bounce Rate or Increase Pageviews/User

What is Bounce Rate?

Bounce rate is the percentage of visitors of your site which leave your site from the very page they arrived at without visiting any other page. The more the bounce rate is, the more worst the case is.

Consider that you get 1000 unique visitors each day, and if your bounce rate is 100% then you get only 1000 page views as all your visitors bounced away right from page they arrived without navigating to any other pages.

So this is important to improve the bounce rate of your website to get more page views at the end of the day. Bounce rate in entertainment websites, news websites are always very good. On the other hand, sites like tips and tricks, solution to specific problem, tutorial sites do not generally get better bounce rate as readers on this website generally arrive with a problem in mind and they take solution and leave it to apply the solution. But this is just a general scenario.

What is Tree in Data Structure? Explain different types of trees.

Tree: 

Data frequently contain a hierarchical relationship between various elements. The data structure which reflects this relationship is called a rooted tree graph or simply a tree. Among different types of data structures in practice, tree is very important to store and manipulate data with complex relationship. This is sometimes like the properties of an object. For example, properties to store of an employee in the office directory can be name, age, sex, salary etc. Again the properties “name” can have sub-properties like first name, middle name, last name etc. This can be showed as follows.

What is Tree in Data Structure? Explain different types of trees.

How to Easily highlight source codes in content?

So if you are a blogger who writes on computer programming and publish source codes in your blog post or if you just want to publish some source codes in your website, then what you can do to stand-out the code from other text is

  • Use <code /> tags
  • Use <pre /> tags
Cool. It will look like codes but not look like as it looks like in your favorite code editor, with different colors for constants, variables, functions, strings etc. along with line numbers.

So, what you want to do is to highlight source codes and make them appearing like in a code editor, which is just not for colors, but for more readability too.

How to Optimize syntax highlighter loading speed?

If you are using SyntaxHighlighter in your blog or website, then you might have noticed that you have to load the brushes you used in a post or page. The way you load them is generally by 

  1. Linking specific brush scripts used on a given page or post, 
  2. Or you load them statically by including all the brushes being used though-out the blog or website.
The first option for loading is disgusting as you have to write the code for each post or pages, however it is better as in this way you load only those brushes you used in an specific post or page.

The second option is better as you don't have to write code for each post or page, but will put impact on website loading speed as you will be loading brush scripts unnecessarily in every post or page despite their usage.

10 Tips to Easily Get Approved by Google Adsense - 2016

Google Adsense is one of those advertising networks which consider publishers very carefully. Even after approval a publisher has to be really very careful as google adsense can ban their account at any moment for violating publishing policies.

However, in this post we will be discussing few easy tips for preparing your website so that you get approved by google adsense with minimum number of applications (yes, I doubt if anyone got approved in first try).

Consider the following easy tips:

5 Easy Ad Management Tips to Increase Adsense Revenue

Google adsense is so far the most preferred way to monetize websites, mobile apps, games, videos etc. It is reliable, robust and full of ads. The fill rate is very close to 100% that you will never see an ad space empty ever.

However, though there will always be ads in your ad placements, it is required to regularly monitor and manage the ads to keep the revenue flow upwards. In the last post, we learnt about 5 Best Ad Positions to Increase Adsense Revenue. In this post, we will learn about 5 Easy to Follow Ad Management Tips to Increase Adsense Revenue.

How to experiment with ad units in google adsense.

Google adsense is my number 1 ad provider because of a lot of reasons like blocking inappropriate ad networks, blocking inappropriate ads, blocking low paying ad networks from serving ads,  customizing ad styles etc. and mostly this one. You can experiment with the ad units you use to publish ads.

Experimenting ad units includes publishing different types of ads (text/image, only text) etc. in an ad unit and finding out which one is performing better than the other and many other types of experiments.

Let's see them one by one.

How to Customize Ad Styles to Increase Adsense Revenue.

Google adsense serves 3 primary types of ads which are banner ads, text ads and link ads. Among these 3 types of ads, banner ads may include images, animated images, animation, video etc. different types of ads.

As per google adsense guidelines, we are not allowed to modify the appearance of an ad. Also it doesn't provide a mean to do that. But adsense provides a way to modify the appearance of it's text and link ads. This is so great. We can customize the ad styles to meet the styles of our webpage.

How to find and block low-paying ad networks in google adsense?

Google adsense is awesome in case of filling your ad spaces or responding to your ad requests. To do this google adsense has a very big inventory ready all the time. But google display ads from third-part ad networks too.

And not of all of these ad networks are high paying ad networks. Some of those ad networks pay as low as $0.05 per thousand impression or much lower. So you should check if you are displaying most of your ads from these kind of low paying ad networks or not. If it is then you should look forward to blocking them.

In our last tutorial we knew that we can find and block less profitable and inappropriate ad categories and specific ads for our blog, so now lets see how to find and block low-paying ad networks in google adsense.

How to block specific ads and ad categories in google adsense?

Google adsense serves ads from variety of categories, from fashion to sports, from movies to education etc. mostly based on the contents of the page on which the ad will be displayed. However, sometimes it shows ads from categories which are not related to content. These are the irrelevant ads and we can block those ad categories and more specifically, we can block specific ads too.

Yes, that's right. So you can see we have enough controls on the ads that appear in our websites. Great, now let's see how to block specific ads and ad categories in google adsense.

5 Best Ad Positions to Increase Adsense Revenue

Google adsense is so far the most preferred way to monetize websites, mobile apps, games, videos etc. It is reliable, robust and full of ads. The fill rate is very close to 100% that you will never see an ad space empty ever.

However, though the ads will appear all the times, it doesn't guarantee revenue generation each time as most of the ads are CPC ads and it will only generate revenue when user clicks on them. Though google adsense is not only a CPC ad network and it also provide CPM ads, but its not in your control to show only CPM ads and google adsense tends to display CPC ads mostly.

Anyway, to increase revenue generated by adsense several things has to be considered along with experimenting with different options available. Steps that we can take to increase revenue can be categorized into 2 main categories; ad positioning and ad management. In this article we will focus in ad positioning in your website.

Get Source Code for Priority scheduling

Priority Scheduling:

In operating systems, tasks that are queued to be processed go through different scheduling algorithms in different operating systems. Priority Scheduling is one of them.

Priority scheduling is like shortest job first except that the next job to process is selected not by the amount of time it will take, but by the priority of the job. So in this priority scheduling each job has a priority value associated with it. The task with shortest priority value gets preferred. 

However, I explained priority scheduling in my another post earlier and as many of my readers wanted to have the source code, here I am publishing the source code of the program. I am not currently explaining the source code, please try to play with it to understand it. I am removing comments intentionally.

Get Source Code for Round Robin (RR) scheduling

Round Robin (RR):

In operating systems, tasks that are queued to be processed go through different scheduling algorithms in different operating systems. Round Robing or RR is one of them.

In round robin, like first come first served, the job or task that comes first, gets processed first, but not fully. Rather in round robin, a portion or segment of the task is completed at once, then the processor moves to the next task and then processes that same amount of task for this second task in hand and it continues. When a portion or segment of all tasks has been processed, the processor starts from the beginning of the task list again and continues to process a portion or segment of each remaining tasks. However in this way, as new task can be continuously added at the end of the task list, the processor might not come back to the head of the list sooner which might cause tasks to be waiting for much longer time ultimately resulting in halted situation.

However, I explained Round Robin (RR) in my another post earlier and as many of my readers wanted to have the source code, here I am publishing the source code of the program. I am not currently explaining the source code, please try to play with it to understand it. I am removing comments intentionally.

Get Source Code for Shortest Job First (SJF)

Shortest Job First:

In operating systems, tasks that are queued to be processed go through different scheduling algorithms in different operating systems. Shortest Job First or SJF is one of them.

In shortest job first, literary, the smallest task among all the remaining tasks will get processed first. 

However, I explained Shortest Job First (SJF) in my another post earlier and as many of my readers wanted to have the source code, here I am publishing the source code of the program. I am not currently explaining the source code, please try to play with it to understand it. I am removing comments intentionally.

Get Source Code for First Come First Served

First Come First Served (FCFS): 

In operating systems, tasks that are queued to be processed go through different scheduling algorithms in different operating systems. First Come First Served or FCFS is one of them.

In first come first served, literary, the task that comes first to be processed gets processed first, then the next one and this continues. This is a less preferable way of scheduling as any task can block the processor for infinite amount of time. Also as all tasks are given the same priority, more important tasks might be waiting too long to be processed.


However, I explained First Come First Served (FCFS) in my another post earlier and as many of my readers wanted to have the source code, here I am publishing the source code of the program. I am not currently explaining the source code, please try to play with it to understand it. I am removing comments intentionally.

How to connect Webmail with Gmail? Send/Receive emails from/to your webmail email addresses right from/in your gmail account.

Webmail is the mail platform that we get when we buy domains. Webmail generally offers three interfaces, Horde, Roundcube and SquirrelMail. No offense, but none of these interfaces offer modern facilities that we get from mail platforms like Gmail, Yahoo Mail etc. So what can we do?

Well, we can connect webmail with Gmail to Send/Receive emails from/to our webmail email addresses right from/in our gmail account. Yes, it's very possible. The recipients will still see that the email was sent from your webmail email address and not your gmail address. 

So let's get started.

Quick & easy Adsense reports and ads management with Google Publisher Toolbar.

Google adsense offers a number very helpful reports for publishers accessible from their dashboard in the reports section. But sometimes we might just need to know the amount we earned today, best performing channels or ad units, information about an ad currently displayed etc. and we might not want to load the whole adsense dashboard. Though loading the adsense dashboard is not a big hassle at all but still, what if a single click bring all these at once along with more features that helps a lot.

Improve adsense revenue with new Page-Level Ads for mobile browsers.

Google adsense is the leading online advertising network form websites, applications for windows, android etc., software, games and many more. Google adsense used to offer banner ads so far, but now it also offers Anchor/overlay and Vignette ads for mobile. These ads are really awesome to improve your adsense revenue. 

What are page-level ads:

Page-Level ads are those ads which you can't place at an exact place of your web page, such as footer or header or sidebar etc. Rather, they appear on their own optimal places. Such as the anchor ads will appear generally at the bottom of the screen and will stick at that position.

Improve adsense revenue with new Page-Level Ads for mobile browsers.


Adsense is not only a CPC network anymore, but also CPM, Active View CPM, CPE.

Google's online advertising network adsense is generally known to most of us as a CPC (Cost per Click) advertising network. That is, a publisher earns money only when users clicks on the ads s/he is publishing. Adsense is a renowned advertising network both to ad publisher and advertiser due to various reasons, mostly because its from google.

But, CPC started to generate less revenue as people started to get used to banner ads that google adsense offers. This is call banner blindness. People now can easily differentiate actual content from ads, no matter how much you customize the appearance of the ad (customizing text and link google adsense ads) using the available options from google adsense. So they ignore the ad and leave the page after they are done with the content. Ultimately resulting no revenue for the publisher, even from thousands of views!

Adsense is not only a CPC network anymore, but also CPM, Active View CPM, CPE.


But, No Worries. Google adsense now offer not only CPC, but also CPM, Active View CPM, CPE types of ads. And also not only banner ads, but also interstitial ad format for mobile, ads in google custom search, video ad etc. We will discus about different ad formats in another post. Today we will look at the different big types only.

What are memory mapped I/O and isolated I/O? What are differences between memory mapped I/O and isolated I/O?

Memory Mapped I/O and Isolated I/O are two methods of performing input-output operations between CPU and installed peripherals in the system. 

Memory Mapped I/O:

Memory mapped I/O uses the same address bus to connect both primary memory and memory of hardware devices (registers). Memory and registers of I/O devices gets assigned values, thus when CPU try to access an address value, it can either from memory or from registers of I/O devices. Memory mapped I/O thus helps in utilizing the same instruction for accessing or addressing both primary memory and I/O device memory locations. 

What are time sharing and real time systems? What are the differences between time sharing and real time systems?

Time-Sharing Systems:

Time sharing operating systems are extension of multiprogrammed batched operating system and the extension is that here the user can interact with the program running. The CPU scheduling algorithm and allocate small amount time to each job at once and then move on to the next job. Thus the user can get output from the program and can input another command and wait for the output. Keyboard is used to input command and monitors are for output. A time sharing operating system allows many user to use the same computer at the same time such as every user is using his own computer. This is achieved by frequently switching from one program to another and satisfying users with an output from the program before switching to the next one.

What are time sharing and multiprogrammed batched systems? What are the differences between time sharing and multiprogrammed batched systems?

Time-Sharing Systems:

Time sharing operating systems are extension of multiprogrammed batched operating system and the extension is that here the user can interact with the program running. The CPU scheduling algorithm and allocate small amount time to each job at once and then move on to the next job. Thus the user can get output from the program and can input another command and wait for the output. Keyboard is used to input command and monitors are for output. A time sharing operating system allows many user to use the same computer at the same time such as every user is using his own computer. This is achieved by frequently switching from one program to another and satisfying users with an output from the program before switching to the next one.

What are parallel and multi-programmed batched systems? What are the differences between parallel and multi-programmed batched systems?

Multi-programmed Batched Systems:

In multi-programmed batched operating systems, the operating system reads jobs from disk drives where a list of jobs are already being stored through card readers. The operating system then pull and store as much job as it can in the memory. Then from the memory, operating system start working on a job. Now, whenever a job reaches a situation where is has to be waiting for one or more tasks to be completed like use of any IO devices, the operating system pulls another job from the memory and starts working on it. Whenever this job also starts waiting, for example it need to use the same IO which is already in use by its previous job, the operating systems pulls another job. This is how, a multi-programmed batched systems harness the power of disk drives and memory.

What are simple batch and multi-programmed batched operating systems? What are differences between simple batch and multi-programmed batched operating systems?

Simple Batch Systems:

Early computers used to take one job at a time, no input in the middle of the process and also no output either. The jobs were prepared commands for the computer to execute on its side and these jobs were generally written on cards, control cards, which the computer used to read through card readers. After processing the job, the computer used to output the data through line-printer machines or tape drives. 

So, the simple batch operating systems were designed to speed up the process by grouping jobs which are similar in nature into one job and execute them and then send back output of each jobs to its programmer. So simple batch systems lack the interaction between the programmer and the machine while it’s running or working on a job.

What are the types or categories of risks in software engineering? Explain the process of risk management.

Risk Management: Risk management is a series of steps that help a software team to understand and manage uncertainty. It’s a really good idea to identify it, assess its probability of occurrence, estimate its impact, and establish a contingency plan that─ ‘should the problem actually occur’. Risk management is a part of umbrella activities.

Simplistically, you can think of a risk as something that you’d prefer not to have happen. Risks may threaten the project, the software that is being developed or the organisation. 

Explain the generations of computer.

Very small amount storage spaceComputer systems reached today’s modern age step by step, these steps are called generations. In each generation computers with new features and functions starts to get the market and the older computers slowly gets replaced. IBM company started categorize the development of computers into generations, though not everyone in the industry including users will be agree on the periods of each generation. However, based on the use of electronic devices, computers systems can be categorized into following generations so far.

Differences between analog and digital computers.

Analog Computer: An analog computer is a form of computer that uses the continuously changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. As an analog computer does not use discrete values, but rather continuous values, processes cannot be reliably repeated with exact equivalence.

Digital Computer: A digital computer is form computer that uses letters and numbers as inputs in processing and displays the result in monitors or other forms of output devices and can also store the output in memory to be used later.

Following are some key differences between digital and analog computer

What are the functions of operating system?

Functions of Operating Systems: 

Operating system’s size, organization and scope of operating vastly depends on the size, organization and use of various computer system. Obviously not all operating systems can be used on all systems. Functions of an operating system are always targeted to meet the needs. Some operating systems are designed to give more flexibility to users, some gives more priority to performance and security and some are designed to be operated by other operating systems, not humans. 

However, following are some general functions of operating systems

How software engineering is different from other types of engineering?

Software project management is an essential part of software engineering. However, good management won’t guarantee success, but bad management results in project failure. Software managers are responsible for planning and scheduling development.  They supervise the work to ensure that it is carried out to the required standards and monitor progress to check that the development is on time and within budget.

Software engineering is different from other types of engineering in a number of way which particularly makes software engineering difficult.

Explain the responsibilities or activities of software project manager?

It is impossible to write a standard job description for a software project manager. The job varies with organization and product being developed.  However, following are the responsibilities most software project managers have deal with.

What are the characteristics of computer?

Characteristics of Computer

Computer became so popular and more important part, unavoidable device of today's world because of its characteristic like correct and dependable outputs, high speed, accuracy etc. Following are the characteristics of computer:

What is computer? What are the four elements of computer? What are the functions of a computer?

Computer:

A computer is a multipurpose electronic device that can receive, store, process data and deliver information. A computer takes data such as numbers, text, images etc. as input and then process those data and convert those to useful information. Additionally, a computer can also store data and information both for future use. Also a computer can do schedules tasks.

Computers are programmed devices. Computer programmers write programs or software for computer which actually takes input, process it and outputs information.

Explain evaluation of information systems.

Evaluation of Information Systems:

The measurement of the efficiency of information systems is the evaluation of information systems. The evaluation of information systems depends on the amount of efficiency in workflow and management an organization achieved by implementing an information system. Evaluation of information systems is measured based on a few criteria as follows

Explain the types of information systems?

An organization's management generally includes one or more levels depending on the size of the organization and it's managing areas. Different types of information systems are required for different purposes of these levels. However, information systems can be categorized into two as follows,

1. Operations Support System
2. Management Support System

Discuss the role of computer in Information System.

Information systems are in use from an ancient time. With the development of computing technology, computers became an important part of today's modern information systems which satisfies speed, dependability etc. 

Following are the role of computers in Information Systems

What is information systems? What are the components or resources of information systems?

Information Systems Definition:

Systems that collect, verify, store, process, report and update data to output valuable and useful information is called an information system. Information systems are being used from ancient time period. With the development of computing technologies and it's uses, modern information systems are computer based information systems which can process billions of data to output desired information in seconds or minutes. Various types of computer based information systems are available.

What is Data and Information? Write the differences between Data and Information.

Data and Information:

Data: Raw materials used in a process to obtain targeted result of goal are called data. In other words, pieces of information which by itself may or may not mean something but useful when connected or used with other pieces of information to form a piece of information that means something, are called data.

Dynamic META Description in blogger template.

Blogger or Blogspot is a free blogging platform from Google. In blogger, you can create a blog for free and just in a few moments, you just need a google account (such as a Gmail Account) to start a blog instantly. If you are familiar with web applications like an gmail, facebook etc., that is enough to start a blog with blogger.

Anyway, though you can create a blog with just a few clicks, you might need some SEO tweaks to have your blog doing well in search engines. SEO (Search Engine Optimization) is a vast thing to discuss. In this post, we will only discuss about META keywords and descriptions in a blogger template.

META description is a small text description of what an webpage is all about. META keywords and descriptions are important parts of any website, such as your blogger blog. This two fields in your template helps the search engine bots to better understand the content of the page. Thus if you write a constant META description that appears in all of your blog pages, contents etc. then the search engine bot will not recognize each of your post well enough. For example, you might be having a post on cricket and another on football. Obviously a common description for these two posts will not help much a bot to understand the posts clearly.

What are the three principal types of critical system?

Types of Critical Systems

Those systems are called critical systems which not only causes inconvenience, no or not-noticeable impact on time, money and life but also causes loss or injuries to life, economical destruction and such bigger impacts when the system fails.

There are 3 main types of critical systems, which are as follows:

What is critical system?

Critical System

Those systems are called critical systems which not only causes inconvenience, no or not-noticeable impact on time, money and life but also causes loss or injuries to life, economical destruction and such bigger impacts when the system fails.

What is software process? What are the 4 activities of software process framework?

Software Process: 

Software Process is a set of required activities and the outcome of the activities with a target to produce a software product. A software process is a flowchart of developing a software product, which includes fathering requirements, analyzing those requirements, scheduling development phases, checking the developments, implementing changes etc. and this can be till the delivery of the final software product to the after delivery service methods and more.

What are the types of software products?

Types of Software Product: Based on how and why the software products are being developed, software products can be of the following two types

What are the conditions for deadlock situation to occur?

Deadlock

In a system, deadlock situations are moments when processes never finish executing and system resources are tied up, which ultimately prevents other processes from ever starting. Dead lock situations are obviously undesirable, however they occur in systems while the following conditions take place simultaneously. These conditions are not completely independent, that is, all four conditions must hold for a deadlock to occur.

Explain an example of Dry Cell or Short note on Leclanche cell.

Example of Dry Cell - Leclanche Cell:

The most common example of dry cell is Leclanche cell invented by French scientist Georges Leclanche. We use to call it a battery. It has a cylindrical Zn container which works as the anode. At the center of the Zn container a carbon or graphite rod is placed vertically in a mixture of MnO2 and graphite powder. The Zn container is then filled up with a paste of ZnCl2 and NH4Cl. The above described Leclanche cell may be represented as follows,

What is chemical bond? What are different types of chemical bonds?

Chemical bond

Atoms of all elements except of the inert gasses have a tendency to combine either with each other or with the atoms of other elements to form cluster of atoms with definite composition. A cluster formed may be either a molecule or an ion. The attraction between the atoms forming the cluster is called a chemical bond.

Nature of bonding and properties of certain solids.

Diamond

Diamond is an allotrope of carbon. Due to difference in bonding in its structure, it looks quite different from the other allotropes. Each carbon atom of diamond is sp3 hybridized. The four sp3 orbital arrange themselves in the four corners of a tetrahedron. Each orbital forms a bond with an orbital of another carbon atom. So, in diamond, each carbon atom surrounded by four carbon atoms arranged tetrahedral forming a giant three dimensional molecule. All the electrons in the outer most shell of each carbon atom is engaged in covalent formation. So, no free electron is found, which makes diamond a non-conductor of electricity. It is also transparent to X-ray and white light as there are no free electrons to encounter with X-ray or white light. Due to its firm rigid arrangement of the carbon atom, with bond distance of 1.54 A, diamond is the hardest substance found in naturally.

Also it needs a high amount of energy to break the bonds between the carbon atoms to turn it into liquid. So its melting point is very high (3500°C) and its density is 3.5.

Briefly explain the formation of dimmers and trimmers.

Some compounds like hydrogen fluorides, ethanoic acids, benzoic acid form dimmers or trimmers by joining up of their two or three molecules by H-bonding. Sometime, due to the formation of these dimmers or trimmers the molecular weight of these compounds appears to be doubled or tripled. That is, ethanoic acid has molecular weight of 60, but in a dimmer of this molecule the molecular weight appears to be 120.

Briefly explain Atomic spectra and Hydrogen Spectra.

Atomic spectra:

When a ray of light is passed through a glass prism, it is dispersed into a band of seven colors. This is called a spectrum. 

When a gas or vapor is heated to a high temperature or subjected to electric discharge, it emits light of all wavelengths. This light, if passed through a prism, a spectrum is formed having single lines or band lines at definite positions and the lines have definite frequencies also. The line spectra are also formed by atoms and are called atomic spectra. The band spectra are actually a collection of many lines formed by a molecule and is also called a molecular spectrum. Line spectra are characteristic properties of elements. 

What is a process in operating system? What are the process states?

Process: 

A process can be thought as a program in execution, but a program by itself is not a process. Process is nothing but a set of instruction to be executed. Multiple instances of a single process can be running at any given time and also a process may create sub-processes with time. Processes may need certain resources like, CPU time, memory, files and access to other devices.

Reasons for building Distributed Systems.

Distributed Systems: 

Distributed Systems (also loosely coupled systems) are also multiprocessor systems but they will not be sharing clock, memory etc. and will be communicating with each other with high speed buses, telephone lines etc. Processors in distributed systems may vary in size and function and include microprocessors, workstations to large general-purpose computers. Some of the reasons for building distributed systems are resource sharing, computation speed up, reliability, communication etc.

Briefly describe different types of operating systems.

Operating systems and computer architecture have had a great influence on each other. As hardware industry started to develop powerful and feature enriched hardware for computers, the operating systems needed to update themselves to harness the power of those hardware. Again, as operating systems started to show what else they can do, hardware manufacturers needed to develop further better hardware. Following is a list of operating systems.

What is operating system? Describe operating systems in brief.

Operating System: An operating system is an intermediary program between computer user and the computer hardware. This computer user can also be just another software running on the operating system or another computer or device. So basically, operating systems are computer programs that let other computer programs or humans communicate with the hardware of the computers. 

What is histogram? How low brightness and high brightness images can be identified from a histogram? DIP

Histogram: 

The histogram plots the number of pixels in the image (vertical axis) with a particular brightness value (horizontal axis). Considering the following graph,

Brightness and Contrast in Digital Image Processing.

Brightness: Brightness of an image is defined by the higher grey-scale values. Such as, if an image has grey-scale values like 175,200,255 etc, it can be said that brightness of the image is high. That is, the higher the grey-scale value the higher the brightness of an image. Thus brightness of an image is the higher values of the grey-scale levels.

Describe the high pass filter. DIP

High Pass Filter: Considering the grey-scale values of a part of an image as below,
Here, we have taken 9 grey scale values. It is seen that the 5th value is very different than the other 8 values, that is a big change is occurring at that point due to the big change of the grey-scale value at that point than the other points. 

Describe the median pass filter. DIP

Median Filter: Median filter, as the name implies, replaces the center value of a mask with the median of all the values of the mask. Simply taking some grey-scale values of an image and taking a 3×3 mask. Now we have 9 values and the 5th value is the median. Thus, the center value of the mask will be replaced by the median. So, the implementation of this filter is as follows,

All questions in Class Notes - Database Management System

Following is a list of all the question in the section Class Notes: Database Management System. When new class notes will be added, links of those posts will be added to this list too.


Draw the database system architecture. DBMS

Following is a flowchart drawing of Database system architecture.

Who is Database administrator? Write some functions of DBA in DBMS

Database Administrator: One of the main reasons behind using DBMS is to have central control on both data and the applications access those data. The person who has such central control over the data is called a database administrator (DBA). Some of the functions of DBA are given below,

Describe different types of database users and their interfaces. DBMS

There are about 4 different types of database users differentiated by their way of interaction with the database system. Brief description has been given below,

What is transaction? What is Transaction Management? DBMS

Transaction: A transaction is a collection of operations that performs a single logical function in a database application. Such as, when we want to add BDT 500 to account A and subtract BDT 500 from account B, that will be a transaction. 

Briefly describe the two-tier and three-tier architecture. DBMS

Two-tier Architecture: In the two-tier architecture, the application is partitioned into a component that resides at the client machine and calls the database system functionality at the server machine using query language statements. Application program interface standards like ODBC and JDBC are used for interaction between the client and the server. 

Describe the components of the query processor. DBMS

Query Processor: As query is very much necessary to find out only the data user need from tons of data of the database, query processor is very important to process these query requests. Query processors come with the following components,

Describe the data structures implemented by the storage manager.

Data Structures Implemented by the Storage Manager: The storage manager implements several data structures as part of the physical system implementation.

What is storage manager? Describe the components of storage manager. DBMS

Storage Manager: A storage manager is a program module which is responsible for storing, retrieving and updating data in the database. 

In how many ways can database constraints be tested/evaluated? Describe briefly. DBMS

Database Constraints: Database constraints are like conditions given to the manipulation of values of a field or attribute. Such as, we may limit the values under the payment attribute of a table that its value can never be less than BDT 350. Constraints can be tested as follows,

Describe Data Definition Language (DDL). DBMS

Data Definition Language (DDL): The specific language used to express the database schema by a set definitions is called Data Definition Language (DDL). The DDL is also used to specify additional properties of the data. Another special type of DDL, called the Data Storage and Definition Language, is used to specify storage and data access methods.

What are database languages? Describe DML (DBMS)

Database Language: As whatever we want to be manipulated by computer has to be written using specific language, database is not beyond them. To write or create database management system we use database languages. They are of two types; Data Definition Language (DDL) and Data Manipulation Language (DML). DDL is used to design a database and DML is used express database’s queries and updates.

What is data model? Describe various data models. DBMS

Data Model: Data model is the structure of the database, which is a collection of conceptual tools for describing data, data relationships, data semantics and consistency constraints. 

What are instances and schema? DBMS

Instances: A database is generally used by many users where insertion and deletion of data occurs frequently. Overall information stored in a database at a particular moment is called the instance of the database. 

What is data abstraction? Describe the levels briefly. DBMS

Data Abstraction: Different users require different view of the database which is useful and necessary to them. This is data abstraction by which we abstract useful data from a database for a particular type of users to use. 

Briefly describe the disadvantages of file processing system? DBMS

Disadvantages of File Processing System: Keeping organization information in a file processing system has some disadvantages including the followings,

What are the applications of DBMS?

Applications of DBMS: DBMS is getting used in many places. Everything from file cabinets to dictionaries is disappearing from today’s working place, because it is easy to make use of the data using a DBMS. The uses or applications of DBMS include the following,

What is Database? Define DBMS (Database Management System).

Database: A database contains a collection of related items or facts arranged in a specific structure. The most obvious example of a non-computerized database is a telephone directory. 

How to double-click & run PHP in CMD/console?

Hello everyone,

Welcome to this short tutorial on how to run PHP codes in console or CMD.

You get PHP console with your PHP setup called php.exe which generally resides in your PHP folder. I have WAMP installed in my computer so I have PHP installed via WAMP.

Wunderlist - Working With Folders

Hello everyone, this is Tanmay Chakrabarty and welcome to this Wunderlist tutorial.

Today we will see how to create folders and keeping task lists inside folders in Wunderlist.

Folder is really very helpful in organizing your lists of tasks, mostly when you are like me who go through a lot of tasks every day and maintain nearly 40 to 50 lists of different categories


Change Start Menu Background to Desktop Background

Hello everyone, this is Tanmay Chakrabarty and welcome to this tutorial.

Alright, you can set your desktop background as the background image of the fancy start menu of Windows 8.1. You can do this in two different ways.



Creating Host File Shortcut to open with notepad as administrator

Hello everyone, this is Tanmay Chakrabarty and welcome to this tutorial.

For us, who works with virtual hosts in windows, opening and editing the host file is pretty common. Mostly among us, who is connected to a network where IP addresses change frequently, is the one who need to open the host file with notepad as administrator.



11 (+2) How To tips for Wunderlist | Best task management app

Wunderlist. Best task management app I have used which is a free task managing app. You can find a lot of similar app for task management. Task managing app is a very much required now a days. As because we started go through multi-tasking. Office, blogging, home etc. So we all now need some kind of task managing app. And what can be better if the app for task management is both free and available on all possible devices, even including apple watch.




Connect to remote MySQL database using SQLyog instead of PHPMyAdmin through cpanel | MySQL GUI Tools

Hello everyone. Today we are going to go through a mysql tutorial on remote database administration. We all know that we can manage mysql database using PHPMyAdmin through cPanel in our web host panel. But sometimes we may not have access to cPanel, but FTP and MySQL login details. So how do you connect at that time without login to cPanel?

10 tips to speed up your website? Web page optimization tips

Hello everyone and welcome to this tutorial on "How to speed up your website? Web page optimization tips".

Whenever on internet it is basically desired to have things happening faster, right? But your website is not performing good enough? Well, here are 10 site optimization tips that will boost your website loading speed.

How to download image from URL using PHP? 2 methods explained.

Hello everyone, welcome to this short tutorial on how to download image from URL and save it on your server using PHP.



Why and How to use static properties in PHP? OOP in PHP.

A static keyword is very important in object oriented programming. Static methods and properties play a vital role in application design and also in design patterns. So what are static methods and properties?



15 Do and Don't Mobile photography tips and tricks

Hello Everyone. For the last few months after buying my current android phone, I have been shooting a lot of photos and also studying about more better mobile photography works. However the following 15 Do and Don't Mobile photography tips and tricks will surely help you. These includes what you should DO and DON'T.


How to backup all databases at once in localhost windows WAMP server

Hello everyone, today with another short tutorial on MySQL and my ultimate MySQL GUI interface of choice, SQLYog. Sometimes, like after a clean windows install or HDD issue or virus/malware attack etc. we need to reinstall our WAMP server. In general our MySQL server also get reinstalled with WAMP and we lose all our databases ! Scary right? Again exporting each and every databases one by one is tedious task for me as my root user on localhost accesses nearly 87 databases. So is there any solution? Obviously yes, if you have got your copy of SQLYog. You can backup all your databases on localhost at once as separate *.sql files or in one file at zip also.



5 tips to speed up your website? These Web page optimization tips will give Sonic Boom

Hello everyone and welcome to this tutorial on “How to speed up your website? Web page optimization tips” PART 02.


So, in my last post on website optimization, which is "10 tips to speed up your website? Web page optimization tips – Part 01", I described 10 ways to speed up your website. If you have missed those tips, I think you should not. Today I will be highlighting 5 more ways to actually give a Sonic Boom to your website. So, lets start.


10 features your IDE (Integrated Development Environment) should have

Coding involves a lot of thing than just coding. Alright, I agree, people can even code in notepad. But choosing right IDE for your everyday use is far more than important. You can open up a program of 40-50 lines in notepad and edit and save it. But what about a whole project of 100 scripts, 200 functions, numerous number of variables and objects and constants, also classes and complex flow or architecture? Stop arguing, and start learning.



Sort dependency list or Topological Sorting in PHP

From Wikipedia


In the field of computer science, a topological sort (sometimes abbreviated toposort) or topological ordering of a directed graph is a linear ordering of its vertices such that for every directed edge uv from vertex u to vertex v, u comes before v in the ordering. For instance, the vertices of the graph may represent tasks to be performed, and the edges may represent constraints that one task must be performed before another; in this application, a topological ordering is just a valid sequence for the tasks. A topological ordering is possible if and only if the graph has no directed cycles, that is, if it is a directed acyclic graph (DAG). Any DAG has at least one topological ordering, and algorithms are known for constructing a topological ordering of any DAG in linear time.

Sometimes, we fall into situations where we have a list of tasks to be done, but with a condition that each of the tasks may need one or more tasks from the list to be done before them. Let’s, consider that we have to do tasks a,b,c,d and the condition is b & d has to be done before the task a, then the sorting will become b,d,a,c.