GCSE Computing/Computing hardware/Input and output devices

Touch sensitive
More and more devices are relying on touch technologies.

What input device might a multi-choice questionnaire writer use to input completed forms into a computer. Why?

Describe the functioning of a bar-code reader:

Describe the functioning of digital camera:

Why might it beneficial for professional photographer to use a digital camera instead of a film camera?

Give two benefits of using RFID cards to pay for produce over using hard cash. What is a draw back?

Give a benefit of having a touch screen phone over a phone with a hardware keyboard. Why might some people prefer a hardware keyboard.

Describe the functioning of a touch sensitive screen:

Scanners
Several of the scanners featured here record biological (bio) measurements (metrics) about human beings. Physical data such as finger prints are unique to each person.

Explain how a flat bed scanner works

Give two examples of devices that collect biometric data

Check digits
With input devices we have a lot of data being sent into the computer, with image capture devices we could be talking about billions of ones and zeroes. How can we make sure that they all get from the input device to the computer safely, without becoming corrupted? There are many error checking methods out there and you will cover some of them in more detail in Unit 1, however, for the moment we will learn a little about check digits:

An example of using check digits (The exam will not expect you to know this technique) is the final digit of a Universal Product Code computed as follows:


 * 1) Add the digits (up to but not including the check digit) in the odd-numbered positions (first, third, fifth, etc.) together and multiply by three.
 * 2) Add the digits (up to but not including the check digit) in the even-numbered positions (second, fourth, sixth, etc.) to the result.
 * 3) Take the remainder of the result divided by 10 (modulo operation) and subtract this from 10 to derive the check digit.

For instance, the UPC-A barcode for a box of tissues is "036000241457". The last digit is the check digit "7", and if the other numbers are correct then the check digit calculation must produce 7.
 * 1) Add the odd number digits: 0+6+0+2+1+5 = 14
 * 2) Multiply the result by 3: 14 × 3 = 42
 * 3) Add the even number digits: 3+0+0+4+4 = 11
 * 4) Add the two results together: 42 + 11 = 53
 * 5) To calculate the check digit, take the remainder of (53 / 10), which is also known as (53 modulo 10), and subtract from 10. Therefore, the check digit value is 7. Correct!

Calculate the check digit for the following food item "01010101010".

Did the following barcode scan correctly: "01234567890 6".

Why do we use check digits?