Unit 1.1 Hardware and Communication Flashcards
Define CPU.
CPU (Central Processing Unit) - the ‘brain’ of the computer. It refers to that part of the processor which ‘processes’ the data and instructions.
State the 3 main parts of a CPU.
- ALU (Arithmetic and Logic unit)
- Control unit
- Some memory storage (Register)
Define ALU.
ALU (Arithmetic and Logic Unit)- which performs the calculations on the data.
Define control unit.
Control unit- which controls all operations inside the computer.
Define register.
Register is a place where a single item of data can be stored.
State 5 ‘things’ all computers have.
- Input device
- Output device
- Some memory
- Program a computer is running
- Data stored in memory
Define RAM.
RAM (Random Access Memory) is the type of memory used for temporarily storing programs and data.
What does memory consist of?
A large number of store locations in which data can be stored.
What are ‘store locations’ identified as?
Address
Define data bus.
Data will need to be moved between several of these elements. The path along which data moves is called a data bus.
What happens when data is saved to (or loaded from) memory?
The address of the store location at which it is to be stored (or loaded) must also be sent.
What is an address bus?
The address of data always travel along an address buss.
State the function of the control unit.
It sends and receives signals from all parts of the computer which makes sure that all processes take place at the right time and in the correct order.
Where does the signals of which processes take place travel along?
Control bus
What does a computer memory consist of?
It consists of a large number of ‘two-state devices’, which can be ‘On’ or ‘Off’.
What digit is stored when the switch is ‘On’?
1
What number is stored when the switch is ‘Off’?
0
What is a bit?
(Binary digIT) is a 0 or a 1.
What is 1 byte?
8 bits
What is 1 kilobyte (K)?
1024 bits
What is 1 megabyte (Mb)?
1024 kilobytes
What is 1 gigabyte (Gb)?
1024 megabytes
What is 1 terabyte (Tb)?
1024 gigabytes
What is all data stored as?
Binary numbers
Define a ‘word’.
It is the number of bits that the CPU can handle at a time (usually 16, 32, 64 or 128).
State 2 types of storage.
- Primary storage - (memory)
- Secondary storage - (backing storage)
State a fact about memory.
It is very fast to store data and retrieve data from it.
Define RAM.
RAM (Random Access Memory) is used for temporary storage of data and programs. It is volatile- the data is lost when power is switched off.
What does RAM consist of?
It consists of a large number of store locations, each of which can store a (binary) number.
What is each store location identified by?
A unique address
Define ROM.
ROM (Read Only Memory) is used for storing permanent data. The numbers in
the store locations cannot be altered. It is non-volatile. The data is never lost.
State Ex.1 of what ROM is used for.
It is used for storing the programs that control embedded systems.
State Ex.2 of what ROM is used for.
It may also store the first section of a program which boots a computer- this is the program which starts running as soon as you switch on a PC.
What are registers?
There are some special store locations in the CPU called registers which are used extensively when a program is being run.
What is RAM cache?
It is a memory chip used to temporarily store data.
Give no.1 function of RAM cache.
It is used to improve the speed of a computer when running a program, because it can supply data to the CPU faster than normal RAM.
Give no.2 function of RAM cache.
It is also used to store the most frequently used data when a program is run.
State an example of RAM cache.
When a loop in a program is executed, the data that is repeatedly used may be placed in cache memory.
What is a disc cache?
It is an area of memory used for storing data when it is input from a disc.
Give an example of why disc cache is being used.
Recently accessed data from a disc may be temporarily stored in cache, because if
it is needed again, it is faster to access it from cache than keep reading it from the disc.
Describe how cache work when viewing web pages.
Recently viewed pages are stored temporarily in cache. A second viewing of the page (perhaps the ‘Back’ button has been clicked) would be loaded faster from cache than downloading the whole page again.
What is secondary storage also known as?
Backing store
Give 4 of the most commonly used secondary storage.
- Magnetic tape
- Magnetic disk
- Optical disk
- Flash memory
What is magnetic tape commonly used for?
Backup and archiving
Describe magnetic disc.
It has fast storage and access to data.
Describe optical disks.
Laser technology is used to read data.
Describe flash memory.
A flash memory chip stores the data.
State 3 facts about a hark disk.
- Available in several sizes (500Gb is possible).
- Permanently enclosed in their drive mechanism.
- Some drives are external and plug in to the USB port.
State an advantage of a hark disk.
It is faster to store and load than floppy disk.
State a disadvantage of a hark disk.
It is sealed; internal drives are not portable.
Give the abbreviation for RAID.
Redundant Array of Inexpensive Drives
What is RAID used for?
To improve reliability. A number of disks are used as one logical unit.
What is the main idea behind RAID?
If one disc crashes, no data is lost because it can be recreated from the other discs.
Give an advantage of RAID.
Increased reliability- so often used on file servers.
Give 2 advantages for DVD.
- Stores up to 17Gb; higher capacity.
- Portable
Give an advantage of a memory card.
It can be used in digital cameras to store pictures.
Give 2 advantages for USB flash drive/ USB memory stick.
- Portable storage media. It can be plugged into the USB port of any computer.
- Typical storage goes up to 8Gb.
State the differences between digital data and analogue data.
Digital data can only have distinct values. Analogue data can vary continuously within a range of values.
State 3 examples of digital data.
- Status of a light switch- it can only be ‘On’ or ‘Off’
- No. of cars passing a point in a road.
- No. of people attending a football match.
State 3 examples of analogue data.
- Person’s heigh
- Sound frequencies
- Temperature in a greenhouse- it can be any numerical value.
Describe a computer.
It is a digital device and so it can only process digital data.
How do computers receive analogue signals?
If an analogue signal is sent to a computer, it is converted into digital signal first by an analogue- digital converter.
What are analogue- digital converters most often found in?
Control systems
State 2 examples of control systems.
- Speech recognition system
- Computer monitoring the temp. of a manufacturing process
Describe an analogue watch.
The hands of the watch can be in any position.
Describe a digital watch.
The time displayed can only be distinct values.
What is a peripheral?
A device which can be connected to a computer and controlled by it.
What does I/ O stand for?
Input/ Output
State 5 input devices.
- Keyboard
- Mouse
- Scanner
- Touch screen
- Digital camera
Describe a keyboard.
It allows characters to be inputted. Used on all computers. Particularly useful in word
processing and command line OS (eg DOS).
Describe a mouse.
Its used on PCs. Directs a screen pointer. Used in a GUI (WIMP) environment.
Describe a scanner.
It scans and inputs images from a printed sheet. Hand-held or flat-bed.
Explain touch screen.
The user touches the screen to select menu items etc. Often used in public spaces, eg libraries, where mouses or keyboards may be stolen.
Describe a digital camera.
It allows photos to be downloaded into a computer and stored.
State 5 output devices.
- Monitor
- Printer
3.Graph plotter - Sound output
- Control signals
Describe a monitor.
Screen displays are composed of a large number of pixels which display ‘dots’ in different colours. High-powered graphics
can be used if a graphics card is fitted into a PC.
Describe a printer.
It is used to create ‘hard copy’.
State 2 types of printers.
- Laser printer
- Inkjet printer
Describe a laser printer.
- Good quality print
- Quiet
Describe an inkjet printer.
- Cheaper
- Slow
- Can use colour
Describe a graph plotter.
It’s used to produce high quality graphics for CAD applications. eg building plans; microchip designs etc.
State 2 types of graph plotters.
- Flatbed plotter
- Drum plotter
Explain sound output.
It’s used in speakers. Useful for music; voices and sound effects for games; spoken warnings in cars; telephone banking. Also used on MIDI keyboards.
Describe control signals.
Computers in control systems will send out control signals to activate devices.
Describe an interface.
It is the hardware and software needed for the processor to be able to communicate with the device.
What is the socket?
It is the port through which signals to and from the device travel.
State 3 different type of ports most PCs come with.
- Serial port (for mouse or modem)
- USB (Universal Serial Bus) port
- Parallel port (for printers)
What is handshaking?
When two devices need to communicate, one device sends a message to the other (‘Are you ready to receive data?’). When the other is ready, it sends a signal back to the first device (‘Yes, I am ready to receive data’)…, and then communication can begin. This exchange of preliminary signals is called handshaking.
Define network.
Consists of a number of computers and peripherals connected together.
State 3 advantages of a network.
- Hardware/ software can be shared
- Data can be shared
- Computers may communicate between each other
How can hardware be shared?
A number of computers can use the same printer.
How can software be shared?
A number of workstations can all load up a program from a file server.
How can data be shared?
A number of computers can access the same database stored on a file server.
How can computers communicate with each other?
Through messages/ email.
State 5 disadvantages of networks over standalone computers.
- Viruses can be spread to all computers on a network.
- Hackers may access computers on a network.
- Network failure means nobody can use the computers.
- Networks may be slower than using standalone computers.
- Complex cabling may be expensive to install.
State the abbreviation for LAN.
Local Area Network
What is LAN?
It is connected by cable, usually on the same site.
State the abbreviation for WAN.
Wide Area Network
What is WAN?
It is connected by telephone or satellite links, possibly in different towns, countries….
What is it meant for networks to adopt ‘standards’?
It is common methods of sending data and consistent data formats.
What would happen if networks were not able to adopt standards?
They would not be able to operate, therefore no communication with each other.
Define protocol.
It is a set of rules for transmitting data across a network.
Why would computers not be able to communicate if there were no protocols?
They would not be able to interpret each other’s transmitted data.
State 7 things protocols have rules for.
- Detecting a connection
- Handshaking
- How to start and end a message
- How to format a message
- What to do about errors
- How to detect a loss of connection and what to do next
- Terminating a connection
State 5 protocols.
- TCP/ IP
- HTTP
- FTP
- SMTP
- VoIP
Describe TCP/ IP.
It is the basic communication protocol of the Internet and other networks.
State the abbreviation for HTTP.
HyperText Transfer Protocol
Describe HTTP.
It is used for transferring web pages
between a client and a server on the Internet. It is also used on intranets.
State the abbreviation for FTP.
File Transfer Protocol
Describe FTP.
It is used for transferring files from one computer to another. Eg. Uploading
web page files to a web server.
State the abbreviation for SMTP.
Simple Mail Transfer Protocol
Describe SMTP.
It is used for sending an email over the internet.
State the abbreviation for VoIP.
Voice over Internet Protocol
Describe VoIP.
It is used for sending voiced messages over the Internet.
What are wireless protocols?
They enable the transmission of data over a wireless network.
Give an example of a wireless protocol.
WAP that allows access to the Internet from mobile phones.
Define portable.
You can carry it around with you.
Give 2 examples of portable devices.
- Laptop computers
- PDAs
Describe laptop computers.
They are battery- powered portable computers that can be used anywhere. They have network cards built in so they can be connected to a network using a cable or by using a wireless connection.
State the abbreviation for PDA.
Personal Digital Assistant
Describe PDA.
It is a small hand-held portable computer. Many PDAs employ touch screen technology.
State 5 uses for PDA.
- Scanning bar codes
- Clock, calendar and address book
- Calculation
- Recording survey responses
- Spreadsheets
State 3 things newer PDA models are capable of being used as.
- Mobile phones
- Web browsers
- Portable media players
What can radio waves be used for?
To transmit data from one computer to another.
Why are wireless networks becoming very popular?
No need to lay a lot of cables.
What does each computer in a wireless network need?
Wireless network card installed together with the software drivers.
What is a wireless hub?
It is connected to the network and transmits and receives data from the computers.
State 2 advantages for wireless network.
- No need for cabling
- Computers can be used anywhere within range of the signal.
State 3 disadvantages for wireless network.
- Data transmission speeds can be slow.
- Data signals can only be received within a limited range.
- Security may be a problem as people may be able to pick up the data signals outside your premises. Careful setting up of the network is needed.
