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Computers
This category includes questions and answers about computers and everything related to computers.
48,002 Questions
What is the different between polymorphism and dynamic binding?
In computer science, polymorphism refers to a computer language's ability to process objects according to their data type. Dynamic binding on the other hand, is a mechanism wherein the method used on an object is being looked up by name at runtime.
What are the four steps a computer follows?
It accepts input, processes data, stores data, and produces output.
Seek time.
What is the interpolation method in computer?
Interpolation tries to predict where something should be based on previous data, movements or a theory.
What are different names and brands within word processing?
Microsoft is of course the most well-known name in word processing, with their Microsoft Office suite. Before Microsoft Office there was Corel WordPerfect, which reached its peak in popularity in the early 1990s, but not many people use it today. Today, the most popular alternative to Microsoft Office is OpenOffice, which is free open source software, but I don't know if you can call that a "brand" since it is open source. Free online word processors, such as Google Docs are growing in popularity, but at this point they are mainly used by individuals and not companies. -DJ Craig
Which data type links files created in other programs such as pictures sound clips or documents?
An attachment is the data type that links files created in other programs.
How much money does a Computer Hardware Engineer earn for it's job?
starting pay 73K ending around 110K
I am one!
What bug did people think would wreck computer systems both in homes and businesses?
The 'millennium bug'. When computers started to be manufactured - no-one gave any thought to the way the internal clock chip functioned. Those older chips only stored the year with the last two digits. Many 'experts' predicted that computers would fail when the year passed at midnight on 31st December 1999. A simple software fix was made available over the internet, and in the vast majority of cases - the new millennium started without problems. Once the 'problem' came to light - manufacturers started producing computers that used the full four-digit number to represent the year. If you're wondering what will happen in the year 10,000 - don't worry - scientists reckon we won't be around then - as the sun will have expanded to a red-giant - wiping out all life on earth !
What is the quality of moleskine notebooks?
The quality of the moleskine notebooks seems very good. The creators of the moleskine notebooks have put a special code on it so that if there are any problems then they can see what's gone wrong with it.
a Dial-up link
What are the criteria for acquisition and acceptability of a software packages?
Software developers often distinguish acceptance testing by the system provider from acceptance testing by the customer (the user or client) prior to accepting transfer of ownership. In the case of software, acceptance testing performed by the customer is known as user acceptance testing (UAT), end-user testing, site (acceptance) testing, or field (acceptance) testing.
A smoke test is used as an acceptance test prior to introducing a build to the main testing process.
Testing generally involves running a suite of tests on the completed system. Each individual test, known as a case, exercises a particular operating condition of the user's environment or feature of the system, and will result in a pass or fail, or boolean, outcome. There is generally no degree of success or failure. The test environment is usually designed to be identical, or as close as possible, to the anticipated user's environment, including extremes of such. These test cases must each be accompanied by test case input data or a formal description of the operational activities (or both) to be performed-intended to thoroughly exercise the specific case-and a formal description of the expected results.
Acceptance Tests/Criteria (in Agile Software Development) are usually created by business customers and expressed in a business domain language. These are high-level tests to test the completeness of a user story or stories 'played' during any sprint/iteration. These tests are created ideally through collaboration between business customers, business analysts, testers and developers, however the business customers (product owners) are the primary owners of these tests. As the user stories pass their acceptance criteria, the business owners can be sure of the fact that the developers are progressing in the right direction about how the application was envisaged to work and so it's essential that these tests include both business logic tests as well as UI validation elements (if need be).
Acceptance test cards are ideally created during sprint planning or iteration planning meeting, before development begins so that the developers have a clear idea of what to develop. Sometimes (due to bad planning!) acceptance tests may span multiple stories (that are not implemented in the same sprint) and there are different ways to test them out during actual sprints. One popular technique is to mock external interfaces or data to mimic other stories which might not be played out during an iteration (as those stories may have been relatively lower business priority). A user story is not considered complete until the acceptance tests have passed. Process The acceptance test suite is run against the supplied input data or using an acceptance test script to direct the testers. Then the results obtained are compared with the expected results. If there is a correct match for every case, the test suite is said to pass. If not, the system may either be rejected or accepted on conditions previously agreed between the sponsor and the manufacturer.
The objective is to provide confidence that the delivered system meets the business requirements of both sponsors and users. The acceptance phase may also act as the final quality gateway, where any quality defects not previously detected may be uncovered.
A principal purpose of acceptance testing is that, once completed successfully, and provided certain additional (contractually agreed) acceptance criteria are met, the sponsors will then sign off on the system as satisfying the contract (previously agreed between sponsor and manufacturer), and deliver final payment.
User acceptance testing User Acceptance Testing (UAT) is a process to obtain confirmation that a system meets mutually agreed-upon requirements. ASubject Matter Expert (SME), preferably the owner or client of the object under test, provides such confirmation after trial or review. Insoftware development, UAT is one of the final stages of a project and often occurs before a client or customer accepts the new system.
Users of the system perform these tests, which developers derive from the client's contract or the user requirements specification.
Test designers draw up formal tests and devise a range of severity levels. Ideally, a system's user acceptance tests and its formal integration and system test cases should not be drafted by the same person. The UAT acts as a final verification of the required business function and proper functioning of the system, emulating real-world usage conditions on behalf of the paying client or a specific large customer. If the software works as intended and without issues during normal use, one can reasonably extrapolate the same level of stability in production.
User tests, which are usually performed by clients or end-users, do not normally focus on identifying simple problems such as spelling errors and cosmetic problems, nor showstopper defects, such as software crashes; testers and developers previously identify and fix these issues during earlier unit testing, integration testing, and system testing phases.
In the industrial sector, a common UAT is a "Factory Acceptance Test" (FAT). This test is performed before installation of the concerned equipment. Most of the time it is not only checked if the equipment meets the pre-set specification, but also if the equipment is fully functional. A FAT usually includes a check of completeness, a verification against contractual requirements, a proof of functionality (either by simulation or a conventional function test) and a final inspection.
The results of these tests give confidence to the clients as to how the system will perform in production. There may also be legal or contractual requirements for acceptance of the system.
Acceptance testing in Extreme Programming Acceptance testing is a term used in agile software developmentmethodologies, particularly Extreme Programming, referring to the functional testing of a user storyby the software development team during the implementation phase. The customer specifies scenarios to test when a user story has been correctly implemented. A story can have one or many acceptance tests, whatever it takes to ensure the functionality works. Acceptance tests are black-box system tests. Each acceptance test represents some expected result from the system. Customers are responsible for verifying the correctness of the acceptance tests and reviewing test scores to decide which failed tests are of highest priority. Acceptance tests are also used as regression tests prior to a production release. A user story is not considered complete until it has passed its acceptance tests. This means that new acceptance tests must be created for each iteration or the development team will report zero progress.
Types of acceptance testing Typical types of acceptance testing include the following
User acceptance testing This may include factory acceptance testing, i.e. the testing done by factory users before the product or system is moved to its destination site, after which site acceptance testing may be performed by the users at the site.
Operational Acceptance Testing (OAT) Also known as operational readiness testing, this refers to the checking done to a system to ensure that processes and procedures are in place to allow the system to be used and maintained. This may include checks done to back-up facilities, procedures for disaster recovery, training for end users, maintenance procedures, and security procedures.
Contract and regulation acceptance testing In contract acceptance testing, a system is tested against acceptance criteria as documented in a contract, before the system is accepted. In regulation acceptance testing, a system is tested to ensure it meets governmental, legal and safety standards.
Alpha and beta testing Alpha testing takes place at developers' sites, and involves testing of the operational system by internal staff, before it is released to external customers. Beta testing takes place at customers' sites, and involves testing by a group of customers who use the system at their own locations and provide feedback, before the system is released to other customers. The latter is often called "field testing".
The cost of IC of TV is Rs 1,450. Is it true or false, i want to know
What does it mean when your computer fan comes on?
The fan tries to stop your computer from going into self destruct mode and is due to excessive heat. The steps you must take are:
1. Buy some cooling liquid at best buy for around 5$
2. Pour a little of it onto the fan
Caution: This can and will
fry computer
make a mess
destroy computer's internal hardware
can harm you
*This may not cool down your computer*
What are the differences between the storage systems?
There are MANY different storage systems. Generally, they're broken up into three classifications:
Magnetic Media
Optical Media
Flash & SD Media
There are others, as well, but they are less frequently utilized.
Within each:
Magnetic Media
-Floppy & Zip Drives
-Hard Drives
-Tape Drives
Optical Media:
-CDs
-DVDs
-Blu Ray
Flash & SD:
-SD Cards
-Memory Stick & Thumbdrives
-Solid State Drives (SSDs)
Now, for a breakdown:
Tape Drives:
These were one of the first removeable read-write mass produced public storage technologies. They worked very similarly to a VHS tape or casette tape. A long thin reel of magnetic tape was rolled past a read-write head to write or read data. Tape drives are still in use today, offering superior storage (up to 40 TB) but at the cost of speed. Tape Drives cannot do random seeks, they must be read sequentially, front to back, to find their data. This may take several minutes of time to find a single file. They are also prone to being damaged or erased by magnetics, fade over time, and can be unreliable. They are also very expensive.
Factoid: Tape drives can be damaged by common magnets fairly easily.
Floppy & Zip Drives:
Replacing the tape drive effectively in the 70's and 80's, the floppy drive originally came on enormous 9" magnetic cylinders and held only a few hundred KB. They were spun in place and a read/write head looked through 'tracks' and 'sectors' to find data. It was much faster, but had many of the same problems. And the read/write head was fragile and prone to break if dust or dirt got on the platter. The platter itself was also very flimsy, and would bend and warp, hence the name 'floppy'. Once they became popular, the 5.25" floppy became standard, holding around 800 KB of data by the time they hit the public. The most popular floppy was the 1.44 MB 3.5" floppy, which featured a hard outer shell and an opening and closing door to protect the magnetic film.
Later, Zip Drives were invented which could stuff significantly more data onto the drive, up to 750 MB in some models. However the advent of CDs, especially burners, caused the zip drive to largely be a failed technology. It, too, was slow and prone to failure.
Factoid: Weak magnets can ruin floppies, enough that putting them near a speaker can damage them!
Hard Drives:
Before hard drives, Drum Drives were used. They were enormous magnetic films rolled across drums which spun, originally the size of oil barrels. These became smaller and faster, and eventually were made into platters. The first harddrives to use platters were made by IBM, and were the size of refrigerators, holding only about 20 MB. Harddrives eventually became smaller and cheaper, and became a much faster, higher-capacity option than floppy disks or tape drives. They were also popular for the reason that they were attached to the computer, usually internally, and allowed you to copy floppies and tapes to the harddrive for long-term, faster storage. This was also when the first widely reported cases of piracy began.
Harddrives eventually became cheaper, smaller, and faster. They work very similarly to floppy disks, however they are enclosed in specialized 'armor' cases and the read/write head is many thousands of times smaller, usually small enough that the very end requires a microscope to see. It floats only a few micrometers or nanometers from the platter, and is significantly more fragile. The read/write head in modern hard drives can snap off if it encounters a particle of *smoke*, much less dust. So many people will not buy a used harddrive if it's kept around a smoker, due to this stigma. Hard drives are much faster than most other media used, but slower than RAM. Since RAM is a precious commodity and very expensive, hard drive space is often used to supplement RAM for either slower, less speed-intensive, or unimportant temporary storage or as overflow in the event RAM runs out. Most harddrives are curretly 50-100 MB/s, while most modern RAM is 3,200 to 16,000 MB/s. As such, using harddrives for RAM causes a violently severe slowdown in performance. This technique is called 'Swapping' 'Swapfile' 'Pagefile' or 'Drumming'. An artifact from the early days of Linux and Unix is the /drum folder where the pagefile is located, a carry-over from Drum Drives.
The read/write head in a HDD is very, very sensitive. Dropping a harddrive or, in fact, even moving it while it's operating (including in laptops!) can cause the read/write head to hit the platter, breaking it. This is called a 'Hard drive crash'.
Factoid: Harddrives can be wiped by very powerful magnets. This used to be much easier but modern drives are better shielded.
CDs:
CDs and their predecessor, Laserdiscs, use a fine wavelength laser to read 'pits' in a plastic or aluminum substrate. This is much faster than floppies and because there is no read/write head and less moving parts, it is much more reliable as well. However it is still unreliable as discs may become scratched, causing it to have to slow down the spin speed to read it clearly, or not at all. It became the de-facto standard for mass data distribution in the 80's and 90's, and is still popular today.
Writeable CDs (CD-R) use a specialized substrate that can be pitted by way of a second, higher-intensity laser. Re-writeable CDs (CD-RWs) use a specialized gel which liquifies when heated and then can be written to and cooled to make permanent data, then heated and re-written to again, allowing the data to be changed. However it has a limited lifespan, usually only 20-100 re-writes before the gel loses cohesion.
By default, CDs hold 650 MB. However overburners can also utilize up to 780 MB CDs. Very few burners can exceed 680 MB, and past 700 MB is almost unheard of, and was never popular.
Factoid: CDs are burned from the center out. The center is the slowest part of the CD, while the outer edge is up to 12x faster. However the outer edge is also much easier to scratch, and more prone to failure.
DVDs:
DVDs are similar to CDs, but use a much finer wavelength and smaller pitting for data writes. It is very comparable, but faster as there is roughly 7-8 times more data passing per revolution.
Bluray:
Bluray is the latest extension of the optical technology. It is about 9 times more dense that DVDs, thus making it much faster as well. It suffers all the same problems as CDs and DVDs.
Thumbdrives & Memory Sticks:
Still a popular method of storage, Flash, NAND, and SRAM memory sticks have been around for some time. While each works a bit differently, the general gist is that memory cells are written to and erased electronically to store data long-term. Except for SRAM, Flash and NAND have a limited lifespan and are prone to sudden failure from use. However they age little or none by reading, only by writing.
SD Cards:
SD cards use a filament to store data, much simpler than Flash, NAND, and SRAM. They can also store much more data in a much smaller area, and for much cheaper. While they are very slow, they are fairly reliable, but also wear out over time from writing. Excessive writing will also cause SD cards to fail early.
SSDs:
SSDs work on Flash and NAND principles but instead of a single device, it takes many cells, sometimes thousands, and combines them for greatly improved speed. SSDs are an eventual replacement for harddrives, even though they are much more expensive and smaller. SSDs use memory cells to store data, and as such they are more comparable to RAM than magnetic media, and are much faster. Most SSD drives are either 30-100 MB/s for older generations, or 80-300 MB/s for newer generations. New PCI-E drives can exceed 1400 MB/s. Also, since they don't need to move a read-write head around like harddrives, tape drives, and floppies, they can load files immediately, making for a very low 'seek time', making the drive respond many hundreds of times faster than harddrives.
The caveat is that SSDs have a limited lifespan, and age every time a cell is written to. Reading does not harm them but excessive writing can make them last much shorter than a hard drive. Most have special circuitry that 'staggers' file placement to use the least-aged cells first. A SSD which does not write has a life expectancy of 40-200 years, however under normal use it is 5-8. This beats harddrives' 3-5 expectancy, but not by much and for a very high price. SSDs are more ideal for speed, or for lower power consumption (as SSDs use typically 2 or less watts, while HDDs average 1-9 watts) than for larger storage or better reliability.
SSDs also have NO moving parts, meaning that they can be dropped and abused in ways harddrives cannot.
What is the set of the computer programs that enables the hardware to perform different tasks?
Typically a Driver.
However this can also include Firmware, and the BIOS/CMOS.
How may computer change the home?
It can change it because it can make everything a whole lot easier.
That's why I always use my computer to do my homework.
Where would you find the post on your computer?
POST - in computing terms - stands for Power On Self Test. It's a series of diagnostic and analytical programs that auto-start when you switch on your computer.
How do you find your Firefox add-ons?
Pre-3.9 :You go to the tools option of the toolbar then to the Add-ons section and the loaded add-ons are there under the extensions window.
Post-3.9
It has it's own button.
