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Computers
This category includes questions and answers about computers and everything related to computers.
48,002 Questions
bar codes work by when the scanner scans the bar code, its looks through the numbers and recognises the item and the price. this is because when the product is made its bar code is made to recognise the item and it is put a price on. they use computer technology to do all of this.
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Basically its till scanners or laser readers consist of a light source and a photo diode that are placed next to each other in the scanner housing (or hand held scanner). To read a bar code, you pass the item across the scanner in a steady even motion. The photo diode measures the intensity of the light reflected back from the light source (the bar-code white and black lines) and generates a waveform that is used to measure the widths of the bars and spaces in the bar code. Dark bars in the bar code absorb light and white spaces reflect light so that the voltage waveform generated by the photo diode is an exact duplicate of the bar and space pattern in the bar code. This waveform is decoded by the scanner in a manner similar to the way Morse code dots and dashes are decoded. It then interprets the wave form in to a numeric code.
i.e.
The last digit of the UPC code is called a check digit. This digit lets the scanner determine if it scanned the number correctly or not. Here is how the check digit is calculated for the other 11 digits, using the code 63938200039 from "The Answers.com world of wonder " (made up name )
Add together the value of all of the digits in odd positions (digits 1, 3, 5, 7, 9 and 11).
6 + 9 + 8 + 0 + 0 + 9 = 32
Multiply that number by 3.
32 * 3 = 96
Add together the value of all of the digits in even positions (digits 2, 4, 6, 8 and 10).
3 + 3 + 2 + 0 + 3 = 11
Add this sum to the value in step 2.
96 + 11 = 107
Take the number in Step 4. To create the check digit, determine the number that, when added to the number in step 4, is a multiple of 10.
107 + 3 = 110
The check digit is therefore 3.
Once the computer (the till or the computer the scanner is attached to) is satisfied that the check digit is right it searches for the code, 63938200039 in its database and when found returns the price, description etc . The same system is used for most products that carry a bar-code from retailers to warehousing to manufacturing to UPS sending parcels world wide.
In the case of a retailer the code, in this case 63938200039 starts life being punched in to the computer which drives the tills. The code is added and a description, price etc is attached to that number. In a retail outlet the company use their own internal code to start the process i.e. 1234 = 750ml bottle of pepsi (or any-other drink) attached to that internal code is the bar-code given to the retailer by the supplier. This is because a product carrying a bar-code can have different information attached by the manufacturer. as an example pepsi in our case on the shelf as a special offer attached to the label. The customer saves 5 labels and sends to the company and gets a free pepsi glass the bar code of a normal (no offer bottle ) may have 63938200039 as its code. The offer bottle will have to have a different bar code because technically there has been a change in some way to the "normal" product so the new code could be 63938200044. The manufacturer tells the retailer of the new code and in the till system now has item;
1234 - Pepsi 750ml bottle - 63938200039
1234 - Pepsi 750ml bottle - 63938200044
The database will now recognise either bar-code as Pepsi 750ml Bottle. This is why on occasion when you arrive at a till in a store they scan the barcode and the till cannot recognise it. The till operator calls for someone to check this - Then it is frequently found that a batch of products has not had its barcode number ntered to teh system.
Why using 555 timer in ir transmitter?
The 555 is a timer and oscillator chip capable of sourcing and sinking 200 milliamperes, and is useful for pulsing an infrared LED to power an infrared transmitter. It can be pulse width modulated or otherwise controlled via the various control pins.
See: http://talkingelectronics.com/FreeProjects/555/555-P3.html
in most cases the IR detector used is TSOP sensors which works only on a specified frequency of 38KHz. So by using 555 timer, we can design the circuit very easly to work @ 38KHz. dats why in 555 is used in many IR txns.
What are applications of computer?
One of the the first mechanical computers was used to tabulate census records. In WWII computers were used to decipher enemy codes. Other applications are for modelling complex problems, such as weather, traffic, explosions of nuclear bombs or stars.
With the advent of the personal computer applications became more prosaic, such as word processing, business spreadsheet analysis, or the design of products like airplanes, automobiles, or microwave ovens (CAD). With the advent of the internet computers could serve as nodes in a global library good for shopping, consulting maps, chatting (Skype), or reading actual books (Kindle, etc.)
Where do you find your wep on your computer?
You only need a WEP key if you connect using wireless. LAN connections do not require a WEP key.
You should be able to find the WEP key by accessing your wireless router.
Usually, to do this, you need to connect to the router using an Ethernet cable. Then open up a web browser (such as Firefox or Internet Explorer) and browse to 192.168.2.1. This is a common IP address for routers. However, some routers are configured differently, so try 10.0.0.1 and 192.168.1.1 as well. If those 3 IP addresses do not work, check Google or the manual to find your router's default IP. NOTE - The IP codes do not work using google chrome
If you are prompted for a password and you have changed it, enter the new user/password. If not, the most common default user/password is admin/admin.
You should now have the setup screen for your router. Go to the "wireless" tab and you should see your WEP key; however, it may be encrypted. If it is, just change the WEP key to whatever you want.
Note to users of Windows 7:
If your computer is connected to the router you wish to find the WEP key of, then follow these steps.
- Open Network and Sharing Center by right-clicking your connection icon at the bottom-right corner of the screen.
- Click the link of the network you're connected to. (Should say "Wireless Network Connection 'router's name here')
- Then click the button "Wireless Properties"
- Then click the Security tab
- It should show your Security, and Encryption type. Also there should be your password in secret bullet form. Simply click "Show characters" and Voila! Your WEP key should be staring you in the face.
Another way of finding the WEP:
Look on the bottom of your wireless router; the numbers that are between the ( ) bars are the WEP key.
What are three applications of computers in education?
1. A SMART board in a classroom for teacher presentations and interactive learning.
2. iPads in the classroom for hands-on learning.
3. Training children on basic word processing and presentation-making when age-appropriate.
4. Using the Internet for research and to answer questions.
What does downloding do to computer?
Depends on the virus's payload. If its a big one, it could potential wreck your computer. If it's small, it could just slow your machine down or do annoying things like cause popups and change your home page.
Can you use ddr ram on your computer that is using sd ram?
Not both at the same time. Most motherboards will be able to support both types of RAM but DDR RAM is much better, due to the double data capability it has. Since RAM prices are quite cheap it would be better if you throw out your SD RAM and buy DDR. No you cannot use both ddr ram and sd ram on the same pc. You have to use either or depending on the motherboard. The slots are different. You can determine what type of memory you have by entering setup in the bios when you turn on your pc. DDR Ram has a slot in the very center of the chip that forms to the slot you plug it into. SD ram has a slot on the chip off set the middle. Hope this answers your question. No you cannot use both ddr ram and sd ram on the same pc. You have to use either or depending on the motherboard. The slots are different. You can determine what type of memory you have by entering setup in the bios when you turn on your pc. DDR Ram has a slot in the very center of the chip that forms to the slot you plug it into. SD ram has a slot on the chip off set the middle. Hope this answers your question
example of analog device is amplifier,op-amp,transistor,transducer etc
and example of digital device is adder,multiplexer,encoder,decoder etc.
Where can one learn about Macintosh Laptops?
There are a few sites dedicated to chronicling information about not only the first Macintosh computer, but every Apple product made before and after then. Some include OldComputers and EveryMac.
How computers manipulates data?
Your question can be looked at two ways. Converting: Changing the overall structure or appearance of the data. The data stays the same, but looks different. Example - changing text that reads "2+4" from red to show up in purple text and enlarging the font. Parsing: Changing the way the data works, or executing a change on the data itself. The data does not stay the same, either through application of rules or programs. Example - changing "2+4" to "6".
Where can you find a computer communication?
You can find a computer communication program online at the MSN and CNET websites. Examples of computer communication programs include Skype, MirandaIM, ICQ, AIM and QQ.
What is a temporary storage location for data waiting to be processed store or output?
Temporary memory is held in RAM, short for Random Access Memory. This memory is not permanent and can be edited or erased easily. It is also erased in the event of a power outage, which is why you should save files to the computer hard drive frequently.
Random Access Memory
RAM, or Random Access Memory is the device the computer uses to temporarily store information while the computer is running.
What is a mainframe computer's processing power?
That depends on the mainframe. The processing power of a mainframe (also known as a "big iron") is measured in several ways: MIPS (millions of processes per second), FLOPS (floating point operations per second) and TEPS (traversed edges per second).
However, supercomputers and mainframes are actually separate types of computer while Gameframes are an amalgamation of the two. Mainframes are typically used in fields of commerce, banking, inventory control, airline reservations, etc. Basically anything that involves large scale transaction processing (moving data from one place to another). Online networking and microprocessor servers have largely replaced the traditional mainframe however a modern mainframe is capable of up to 50 billion instructions per second.
Supercomputers are way more powerful, and are used to predict weather, perform nuclear simulations and anything else that involves high-precision mathematics at high-speed. As of June 2012, Sequoia, the IBM BlueGene/Q system is the fastest supercomputer on the planet, measuring in at 16.32 petaflops (16,320 trillion FLOPS).
Difference between a dual core and a core 2 quad?
The quad core is better. As its 4 cores, the workload is spread efficiently between them so it runs smoother. But the quad core is more expensive.
The Intel Core 2 Duo processor was designed to meet the demand for increased performance from PC users. It can run multiple, intense software applications simultaneously.
Why is a dot matrix printers are not suitable for a hospital?
The printing technology (dot matrix, inkjet, laser, etc) doesn't normally limit its use, but each printing technology has specific characteristics which may prevent, or promote, use of a given technology in a given application or environment.
Dot matrix printers are fairly noisy printers and may thus be unsuitable for use near patients. However, dot matrix printers can create carbon copies, and are thus often preferred over more modern technologies such as inkjets or laser printers.
Assuming the printer can be places such that the emitted noise doesn't impact patients, a dot matrix printer may be the perfect solution even in a hospital, for example if a single printout should produce multiple copies (e.g. one for the patient's files, one for the nurses' records, etc...).
How fast can a computer compute?
To qualify as a supercomputer, a given computer must have at least 10 times the speed and memory of other computers available in its time period. Therefor this is a sliding scale, as other computers improve, new supercomputers must race ahead to get or keep the title.
Why would your computer restart after being turned off?
it forgets what u last did! and there is probaly something wrong with your computer....
What is cross domain contamination in computers?
Cross domain contamination occurs when two computers from two different domains are sharing information, and it is somehow vulnerable. To prevent this, an SOTTC client is often used.
What does it mean to burn a disk?
Burning a disk means to write data onto it.
By looking at the categories you have assigned, you are looking to "burn" or put songs onto a disk.
Be aware there are two results: a "data" disk you can only play in a computer, an Audio CD you can also play in a CD player.
That all depends. Most Z270 Motherboards will fit.. the case supports ATX, Micro ATX, and Mini ITX form factor boards. But you will not be able to fit E-ATX motherboards.
Is it possible to share files from a PC to a Blu-ray player?
If your player allows USB flash drives and/or SD cards, then yes
Does turning down the brightness on your computer save energy?
of course it does, you don't use the energy to keep it running, hence, you save energy.
