X) Input/ Output and secondary storage devices + ( Hardware & Software)

Question 1

How do Barcode Readers scan barcodes?

Answer 1

Light from a laser is directed at a pattern, a light sensor detects the intensity of light reflecting back.
- A black bar absorbs more light, so there is little light reaching the sensor (0).
- A white bar reflects most of the light, so the sensor detects a higher level of intensity (1).
The waveform is analogue and therefore an analogue to digital converter is used to convert.
The pattern of 0s and 1s creates a unique identity.

Question 2

Two types of barcode systems?

Answer 2

-Universal Product Code version “A”, used in retail and warehousing.
Only represents numbers.
-Code 128, used in transport and tracking shipment.
Can represent letters and numbers.

Question 3

UPC-A / EAN systems

Answer 3

In the barcode, there are long guard bars to show the start and end of the barcode, with a central guard to distinguish left from right.
Uses 7 bar elements to form 4 alternating black and white bars to represent each data item between the guards.
Left number: Manufacture Number
Right number: Product Number

Question 4

Quick Response (QR) codes

Answer 4

QR codes are 2D barcodes that are read by smartphones, they contain links to websites or information. 
Uses:
- Business Cards
- Tourist information
- Restaurant coupons

Question 5

How Digital Cameras capture an image?

Answer 5

When the camera takes a picture, light is let into the lens.
The light is focused onto a sensor called a charge coupled device (CCD).
The sensors are made of transistors, each storing data about each pixel.
Each sensor filters the light into different colours (Red, Blue and Green).
As the light hits the senors is converted into electrons, the amount of charge is measured in digital form.

Question 6

How Digital Cameras store an image?

Answer 6

The data is stored on removable storage devices also known as flash memory.
The data is compressed and stored in files such as JPG & PNG.
RAW files can be created, which are uncompressed files containing all the original image data.

Question 7

How do laser printers work?

Answer 7

The printer puts the data into a format that the printer can process.
The data is then stored in a printer buffer.
The process starts by giving the printer drum a -ive charge.
As the print drum rotates a laser beam scans across it removing the -ive charge, this leaves areas of positive charge.
The print drum is cover with a -ively charged toner which only sticks to the +ively charged parts of the drum.
A +ively charged sheet rolls over the drum, the toner sticks to the paper producing an exact copy of the text/image wanted to be printed.
The paper goes through a fuser which bonds the ink.
Finally a discharging lamp removes the charge on the drum ready for the next print.

Question 8

Radio Frequency ID (RFID)

Answer 8

An RFID uses a receiver that emits a radio frequency.
The transponder in a bank card, mobile phone or tag becomes energised by the radio waves.
The transponder can then send data to the receiver.

Question 9

Uses of RFID tags

Answer 9

• Security control points, to identify a person, animal or object.
• Shipping, to track goods.
• Banking, fast-contactless payments

Question 10

Passive Transponders and Active Tags

Answer 10

• Passive transponders are used in bank cards, as they have no power source and rely on radio waves from a receiver for their energy.
• Active tags use a larger, battery-powered beacon that broadcasts its own signal up to 300m away.

Question 11

Hardware Definition

Answer 11

Refers to the physical components of a computer and relative devices. 
Internal hardware (Components): CPU, Motherboard & RAM. 
External hardware (Peripherals): Monitor, printer & keyboard.

Question 12

Classification of software

Answer 12

Two main groups:

System Software:
           -Operating Systems 
           -Utility Systems
           -Language Translators
            -Library Programs
Application Software:
            -General-Purpose Applications 
             -Special-Purpose Applications
            -Bespoke Applications

Question 13

Application Software

Answer 13

• General Purpose Application- is software that can be used in many different ways, e.g. word processor, spreadsheet & desk-top publishing package.
• Special Purpose Application- a software specific to an organisation, often customised to fit the needs of a specific system needed. e.g. a system for running a factory. (One specific function).
• Bespoke Application- software written by developers for one particular organisation.

Question 14

Utility and Libary Programs

Answer 14

• Utility programs- they enhance the use of a computer, no specific common tasks. E.g. Anti-virus software, file manager & File Compression.
• Library programs- code, data and resources that can be called by other programs. For example, Python library files, built-in modules for handling data types and performing mathematical functions.

Question 15

Assembly Language

Answer 15

Assembly language is where commands are translated directly into one command in machine code.
There is a very strong connection between assembly language and machine code as assembly language words is basically machine code in words.
The code is not easy to understand and before any code is written it has to be executed in machine code by an assembler.

Question 16

Interpreters

Answer 16

An interpreter is a program for translating a high-level language by reading one statement at a time in the source code and immediately performing the action.

+ives:

• No need to compile the whole program
• Code is translated each time it is executed, so is most likely to be used during the development stage of a program.
• ives:
• Overall time needed to execute can be very long.
• Source code can only be executed if the computer has the same interpreter installed.

Question 17

Compliers

Answer 17

A compiler is a program that translates high-level language code into machine code. A compiler translates the whole program in one go.

+ives:

• Once the source code has been compiled, the compiler is not needed again.
• If you want to pass your object to someone else they will find it hard to work out what the source code originally was.
• ives:
• The object code will only run on the same computer which has the same platform.
• As the program has to be converted from source code to object code the time taken to make the slightest alternation will take a long time to debug.

Question 18

Mnemonics

Answer 18

Mnemonics are shortcodes used as instructions when programming such as; LDR & ADD.

Question 19

Operating Systems

Answer 19

The OS links together the hardware, software and user but hides the complexities of using a computer,
its a virtual machine.

Question 20

What tasks does the Operating system perform?

Answer 20

• Controls startup options
• Allocates and manages memory
• Deals with errors and sends out error messages
• Manages security
• Manages input/output devices

Question 21

Magnetic Hard disks (HDD)

Answer 21

A hard disk is a secondary storage device made up of metallic disks that store data magnetically.
The disks are hermetically sealed, to prevent debris from corrupting the disks.

Question 22

How do HDDs work?

Answer 22

An HHD consists of disks arranged in a stack, the disks are coated with a magnetic material, with the changes in the direction of magnetism represents 1s and 0s.
Hard disks spin at between 3600 - 12500rpm, as a series of read/write heads write data onto the disks.
There is an actuator arm that allows the head to move across the surface of the disk. The combination of the actuator and the rotation of the disk means the head can access all parts of the disk.
The surface of the disk is organised into tracks, each track is split into sectors, each of which can be addressed by the OS.

Question 23

Optical Disk (CD, DVD)

Answer 23

An optical disk is a disk that use laser technology to read and write data.
They are read only.

Question 24

How does an Optical Disk store data?

Answer 24

The disk is made up of one single spiral track which starts in the middle and ends at the edge.
The laser will read the data that is contained within the track by reading the pits and lands.
The continuation of the land or pit represents 0 and the transition between the land and the pit represents a 1.
The spiral track can be made tighter leading to more data being stored on the same physical disk.

Question 25

How is data read from an Optical Disk?

Answer 25

A low power laser of light is shone on one spot on the track.
The amount of light reflected back is measured and if a high amount of light is detected then it represents a 0.

Question 26

Solid State Drive (SSD)

Answer 26

A drive that is made up of semiconductors and is non-volatile.
SSDs use ROM chips and use a type of memory called NAND memory.

Question 27

Advantages and Disadvantages of HDDs and SSDs

Answer 27

HDDs
\+ives:
-Large storage space: 521GB- 4TB
-Cheaper than SSDs 
- Fast access speed

• ives:
• Volatile
• Easily damaged
• Not as fast as SSDs

SSDs:
\+ives:
-Non-volatile 
- Very fast access speeds
- Very high capacity

• ives:
• Expensive