B) the video card is a circuit which generates video output
B) deals with input and output of sound
C) picks up wireless signals
D) the main circuit board which holds the CPU, the memory chip and other connections
E) this is the ROM and the ROM
F)this is the hard drive
Explain the following, by giving examples where necessary:
d) Embedded computers
a) this is a large computer at the size of a small house; it was first developed in the 1960's. They are reliable because they have multiples of each component (if one becomes faulty the system would continue working).
B) servers communicate differently because they have no monitors nor keyboards. They become large by connecting many machines - the more the faster and vice versa.
Servers and mainframes are used in large companies such as banks and e-commerce firms where a lot of processing is necessary.
C) supercomputers contain the fastest processor that manufacturers can make.
D) Embedded computers are in everyday objects such as TV's, remote controls, microwaves, fridges, cars, watches etc...
What is a software?
Software is a program which has sets of instructions that keeps the hardware together. there are two types...
1) operating system (OS) - this software controls whole computer - examples are Windows, Mac OS X and Unix.
2) the OS also runs application software which is things like word processor, games and spreadsheets.
What is a E-book reader?
It is a smaller tablet designed for storing and reading books. It has a non-reflective screen which mimics the actual appearance of the ink on the page. They are lighter than other tablets and have longer battery lives.
How does an optical mice and an older mice work?
An optical mice works by using a sensor which works out its movement by tracking the movement of the surface below it.
The older mouses used a ball which rotated as the mouse moves and the sensors measured the movement of the ball in two directions.
How are Graphic Tablets or sometimes called digitisers used?
This involves a touch sensitive screen and a rigid stylus. The stylus presses it down on the screen and the touch sensitive screen registers its position and it is displayed on the monitor.
Explain what OMR and OCR are!
Optical character recognition is a software which takes scanned digital images and looks for patterns that makes up numbers or letter; it stores it as a text file to edit using word processing. It is good for entering large blocks of text but it isn't perfect - must be proof read.
Optical mark recognition uses a scanner which reads the carbon marks made onto a piece of paper. They are used for registers. it is quick and accurate but only of the sheet is filled in properly.
Input Devices - Explain the Following...
B) a digital camera takes images and stores the data in bits called pixels. This could be uploaded onto a computer and edited using photo-editing software. They can record videos too but video cameras are better for a lot of footage.
Benefits - image is immediately available and can be sent as an attachment all over the world.
disadvantages - it produces high resolution images which requires a lot of memory.
B) microphones uses the voice-recognition system which converts sound into text or a command. They are also used for recording sounds and could be digitally sent over teh internet.
Disadvantages - sound data uses a lot of memory
Benefits - dictation instead of typing
C) midi instruments enters music into a computer. As an example a keyboard could be played and the notes would be stored and could be edited.
Benefits - Sound of note (instrument) coule be easily changed
Disadvantage - this system is expensive
How do laser printers work?
(advantages and disadvantages too!)
It has a electrostatic rotating drum (it has an electrical charge). There is laser etches onto the drum a negative image by using the electrical charge of the drum. The negative ink in the toner cartridge is attracted to the positive drum and inserted onto the piece of paper. Finally there is a fuser unit which is paper heats up to fuse the ink on it.
Advantage - They are quiet. They are fast producing more than 10 pages per minute (ppm). They also create good quality images - up to 600 dots per inch (dpi).
Disadvantages - expensive to buy and to repair from its complex equipment.
How do inkjet printer work?
(Advantages and disadvantages too!)
Its main component is the print-head.
This type of printer has a nozzle which sprays a jet of ink onto a piece of paper through a nozzle. The flow could be changed by...
1. using a different shaped crystal in the print-head.
2. heating the ink expands it making it move
3. some printers have continually flowing ink. Unused ink is electrically charged and diverted back by the charged plates.
Advantages - high resolution images; 300 to 600 dots per inch (dpi). They are cheap and its small size makes it suitable for home use.
Disadvantages - They are slow (ish); up to 4 ppm when color is used. They also require more cartridge than laser printers.
What is Buffering and spooling in terms of printers and why is it really important?
Computers process data faster than printers can print it. Thus, to avoid the holdup:
1) The printer could buffer - it has its own memory and stored in the printer. It stores the data about the pages to be printed and the user can continue to do other things.
2) Spooling is similar. However, this time the information about the pages to be printed are stored on the Hard Drive to free the CPU and to allow the user to do other tasks.
Answer the following questions...
1. What were the old heavy and Bulky computers?
2. What are and how to Graph plotters work?
1. The old, heavy and bulky ones were CATHODE-RAY TUBE ones.
2. Graph plotters are specialized printers. They are an alternative to laser printers when more accurate drawings and drawings on bigger pages are required. The graph plotter is generally flat bedded. A plotter arm moves right and left on the surface. However, on the arm there is a pen which moves up and down encouraging it to draw accurate lines in any direction.
Other output devices!
1. how are external devices controlled?
1. External devices are controlled by the signals emitted from the CPU. This is the same for internal devices too.
What are ACTUATORS and what are the different types?
Actuators are controlled by a control interface. It is able to do simple mechanical tasks automatically.
1. MOTORS and there are 2 tpyes:
A) Stepper motors take small but equal and accurate steps - they are used in flat bedded scanners.
B) servo-motors are continues and are really fast. Thus they are ideal for computer operated drills.
2. HYDRAULIC ACTUATORS - these use liquid pressure from a computer to do tasks which are slow but that requires a lot of energy - ideal work lifting equipment for construction.
3. PNEUMATIC ACTUATORS - these use air pressure from computers to do tasks requiring less power but a quicker response - ideal for powering robots.
What is the RAM?
The RAM is the temporary memory and stands for Random Access Memory. The RAM could be volatile or non-volatile. Volatile RAM looses its contents when the power is switches off. With non-volatile RAM power is required to make changes but is keeps its contents even when the power is switched off.
The RAM and Hard Drive are different. The Hard Drive is a permanent data store, whilst the RAM is temporary and easier to access.
If there isn't as much RAM as the computer would like to use, it would use the Hard drive as the "overflow" memory; access becomes slower. By adding more Ram, you would increase the processing power. The memory and the number of programs it could run at the same time.
Show how data grows in size by explaining the Binary and Morse Code!
Computers consist of many circuits. They are either on or off. The BINARY CODE uses two digits to represent this, whilst the MORSE CODE uses dots and digits. Each individual 1 or 0 is a bit - from the binary digit.
8 bits = 1 byte
1000 bytes = 1 Kilobytes (KB/K)
1 million bytes = 1 megabytes (MB)
1 thousand million bytes = 1 gigabytes (GB)
1 million million bytes = 1 terabyte (TB)
What is the ROM?
ROM stands for Read Only Memory. It is a permanent memory store; thus, it is non-volatile. However, the amount in most computers is small compared to the RAM.
The ROM, loads the operating system from the backing store (i.e. hard drive) to boost the computer up. Sometimes the operating system is kept on the ROM - as an example, in mobile phones and PDAs.
The hard drive is the main data storage in a computer. Explain how it reads and writes data!
The hard drive is stacks of magnetized circular plates which have concentric tracks and sectors. Data is stored on both sides of each track. There are read/write heads floating very close to the surface of the dick - thus, a speck of dust would ruin it. Consequently, it is kept in a sealed unit.
You could also buy external hard drives for transferring data between computers and for more storage.
Advantage - it has a great capacity - hundreds and thousands of gigabytes.
Disadvantage - if there is a problem with the hard drive all data may be lost.
What are solid state drives and why are they more robust compared to hard drives?
These work in the same way as hard drives. However, they have no moving parts. Consequently, they can withstand shocks and regular movements - they are ideal for mobile devices. They also provide quick and easy access to data. However, they are expensive compared to hard drives.
What are optical dicks and what are the different types that you could purchase?
Optical discs are compact discs (CD) and digital versatile discs (DVD). Data gets stored as pits on it reflective surface. The data is then read by a laser beam going over the reflective surface and by reading the change in the position of the laser beam.
1. There are 3 types of compact discs (CDs) -
A) CD-ROM - data could only be read (cannot write on them). However it could store up to 650 megabytes.
B) CD-R (R= records) - you could buy a blank CD and write on this disc, but only once. After that it is the same as the CD-ROM; Write Once Read Many times (WORM).
C) CD-RW (RW = re-writable) - can delete and write as many times as you like.
2. Digital Versatile Discs are similar but can store much more data - up to 8.54 gigabytes (ideal for digital films). There are also DVD-RAM (similar to CD-RW) which is used when data is frequently updated and changed.
3. Blue-ray discs are like DVDs but store up to 6 times more data than a DVD- good for storing films at high definition.
What is a flash memory? Consider...
a- how much data could it store
b- is it volatile or non-volatile
c- how strong?
d- its speed
e- where are they used
f- explain a Windows 7 feature
Flash Memory is non-volatile and could store gigabytes of data. They are faster than hard drives but slower than the RAM. They wouldn't break easily, but would eventually wear out.
They are inserted into small devices such as memory cards, USB and memory sticks which are either inserted into the USB slot or into the memory card slot.
Flash memory could be used in memory cards - they store data and transfer it between computers just like a USB; used in MP3 players, cameras and mobile phones.
The Windows 7 allows memory sticks to be used as a temporarily data storage between the RAM and the hard drive to make the computer faster.
Why is the access time of magnetic times slow?
Why do people still use them?
It is slow because to find specific information the read/write head cant just find it. Instead it would wind through the entire tape; this is called serial or sequential access.
However, it is a way of storing large amounts at a relatively cheap price.
What does ISP stand for?
What is the purpose of storing data online?
ISP = internet service provider
By storing data online you are asking an internet service provider to look after your data. Its main purpose is to back up, to give you the ability of access your files on any computer as long as there is internet, and to allow us to share files (e.g. holiday pictures) with other people.