• By setting the validation rule for the input controls on the property sheet in design view
• By use of VBA to restrict user inputs for a given control on a form
• By use of queries to restrict options available for the user in a combo box or listbox
• Setting correct data types for the fields in table the design
• Enforcing referential integrity in database relationships
• Use of input mask for the controls on the property sheeet in design view

• Real-time OS reads information from input devices and must respond within a short duration of time to ensure correct performance
• Distributed OS distributes computation among several physical processors which do not share memory or clock

• By use of an ergonomic keyboard
• She should take regular breaks from her computer and stretch her joints
• She should use standard furniture with an upright backrest to reduce strain on the back

• Single-mode fibre consists of a narrow core in which all light pulses travel at the same speed and arrive roughly at the same time at the destination.
• Supports higher bandwidth with less signal loss over a greater distance
• Multi-mode Multi-mode fibre consists of a larger core in which multiple light pulses can travel down the core.
• Supports a smaller bandwidth and signals attenuate at a shorter distance than single mode fibre.

1. (a)State what is meant by the terms:

Parallel data transmission

• 8 bits/1 byte/multiple bits sent at a time  

1. using many/multiple/8 wires/lines

Serial data transmission

• one bit sent at a time  
• over a single wire

b) Give one benefit of each type of data transmission.

• Parallel - faster rate of data transmission

Serial

1. -more accurate/fewer errors over a longer distance
2. -less expensive wiring  
3. less chance of data being skewed/out of synchronization/order

Give one application of each type of data transmission. Each application must be different

Parallel

• sending data from a computer to a printer
•  internal data transfer (buses)

Serial

• connect computer to a modem

State what is meant by the term USB

• universal serial bus

Describe two benefits of using USB connections between a computer and a device.

• -devices are automatically detected and configured when initially attached
  • Impossible to connect device incorrectly/connector only fits one way
  • has become the industry standard
  • supports multiple data transmission speeds
  • lots of support base for USB software developers
  • supported by many operating systems
  • backward compatible
  • faster transmission compared to wireless

DVD - optical media which use one spiral track; red lasers are used to read and write data on the media surface; makes use of dual-layering technology to increase the storage capacity

ROM - non-volatile memory chip; contents of the chip cannot be altered; it is often used to store the start-up routines in a computer (e.g. the BIOS)

SSD/ Solid State Drive/memory (SSD): a non-volatile memory device that uses NAND flash memories (which consist of millions of transistors wired in series on single circuit boards)

Blue Ray -  optical media that uses blue laser technology to read and write data on the media surface; it uses a single 1.1 mm polycarbonate disc

Viruses, pharming and phishing are all examples of potential Internet security issues.
Explain what is meant by each of these three terms.

Virus

• - program/software that replicates/copies itself
• – can delete or alter files/data stored on a computer
•  – can make the computer “crash”/run slow

Pharming - malicious code/software installed on a user’s hard drive/actual webserver

 – this code redirects users to a fake website (without their knowledge)

 – to obtain personal/financial information/data

Phishing - legitimate-looking emails sent to a user – as soon as the recipient opens/clicks on the link in the email/attachment,  the user is directed to a fake website (without their knowledge) – To obtain personal/financial information/data

control bus- this bus carries signals used to coordinate the computer’s activities

address bus - this uni-directional bus carries signals relating to memory addresses between processor and memory

data bus - this bi-directional bus is used to exchange data between processor, memory and input/output devices

The seven stages in a von Neumann fetch-execute cycle

• the PC (program counter) contains the address of the next instruction to be fetched
• the address contained in the PC (program counter) is copied to the MAR (memory address register) via the address bus
• the instruction is then copied from the memory location contained in the MAR (memory address register) and is placed in the MDR (memory data register)
• the entire instruction is then copied from the MDR (memory data register) and placed in the CIR (current instruction register)
• the value in the PC (program counter) is then incremented so that it points to the next instruction to be fetched
• the address part of the instruction is placed in the MAR (memory address register)
• the instruction is finally decoded and is then executed

Modern LCD monitors and televisions use LED-backlit technology.
Give two advantages of using this new technology compared to the older cold cathode fluorescent lamp (CCFL) method

• no need to warm up
• – whiter tint/more vivid colours/brighter image
• – higher resolution
• – much thinner monitors possible/lighter weight
• – more reliable technology/longer lasting
• – uses much less power/more efficient

•  It does not have declaration part
• It does not  have control structures

• online storage
• incremental backup
• full backup
• RAID (level 0, 1, 10)
• uninterruptible power supply (UPS)

• Knowledge base – is the systems’ database of knowledge about a particular subject. It contains relevant facts, beliefs, assumptions and procedures for solving a particular problem
• Inference engine – this is the software that controls the search for knowledge in the knowledge base and produces conclusions. It takes the problem posed by the user and seeks to analyze it in order to arrive at a conclusion.
• User interface- this is the display screen that enables the user interact with the system.

• Sequential
• Random
• Serial
• Indexed-sequential

Router

• Easy to add nodes
• Managed centrally
• Fewer data collisions
• A single node failure does not affect the rest of the network

• Broadcast Radio
• Infrared
• Bluetooth
• Microwaves
• Satellite

A computer system refers to computer components that collectively function as a single unit to achieve the desired goal. It can also be defined as a collection of hardware, software, and liveware that work together to receive, process, and manage data

Manages memory (RAM)

•  Allocates memory to programs currently executing 

Ensures programs/data do not corrupt each other

• Ensures all programs and data including itself is stored in correct memory locations

Manages processes

• Ensures different processes can utilise the CPU and do not interfere with each other or crash  

Allows the user to run programs 

• On a multitasking operating system, it ensures that all tasks appear to run simultaneously 

Other roles

• Allocates time slices
• Scheduling of programs
• Handles interrupts
• Allows the user to configure hardware

• An agreement / set of rules / standard for how computers should communicate or how data is sent/received/transmitted on a network
• Example of what could be agreed in the protocol (e.g. speed / error checking / etc.)

• System software manages the computer hardware/application software
• application software is for end-user tasks

• user changes his mind
• new government legalisation/company policy company changes
• changes in hardware
• changes in software/upgrades/new versions
• improved operating efficiency/ease of use

Twisted pair cables

Coaxial cables

Fibre optic cables

• car factories/factories
• chemical/nuclear factories
• production lines
• warehouses
• deep in the ocean/down mines
• on other planets/in space
• road junctions