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Q&A- Computer Studies

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)

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

  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

 

  • Distributed data processing is where computers located in physically separate location transmit data after processing to a server computer that updates the master file. Time-sharing on the other hand is where various terminals transmit data to be processed by a central computer's CPU. Each terminal's tasks are allocated a time slice of the CPU
  • A physical file contains the original data whereas a logical file does not contain any data
  • A physical file contains one record format while a logical file can contain up to 32 record formats
  • A physical file can exist without a logical file while a logical file cannot exist without a physical file
  • two's complement has only one value for zero

Prefixing an extra sign bit- A negative number is representes by prefixing a digit 1 to the number

Ones complement- This is flipping the binary equivalent of the number

Twos complement- this involves getting the ones complement and then adding a 1

  • Simple technology is needed to develop both hardware and software.
  • Digital devices are more reliable, small in size and use less power as compared to analog devices.
  • Devices that read, process or output data in digital form are used in computers and other digital devices such as calculators.
  • Hierarchical model  - Records in the database can be related to one parent only but can have more children records
  • Network database model - a child record can be linked to  multiple parent records
  • Relational database model - organizes data into tables that can be linked or related based on data common to each.
  • It is the use of proofing tools like spelling and grammar checkers and autocorrects to check whether a document has typographical or grammatical errors
  •  It does not have declaration part
  • It does not  have control structures
  • Object code refers to a program in machine language while source code to a program in a high level language that must be translated to object code for it to be machine readable
The process of developing computer programs to solve a particular problem

Sequence:Sequential execution of a program one line after another

Selection: Involve the a decision between two or more options e.g  if...then...else

Loops/Repetitions:use for looping i.e a line of code can be made to execute a given number times before terminating.