Computer Science Paper 1

• Function of CU


  -Control Unit- manages fetch-execute, coordinates flow of data within CPU
• Function of Cache


  -Cache- Very fast memory- stores only frequently used data- otherwise RAM
• Function of ALU


  -Arithmetic Logic Unit- calculations, binary shifts, logic operations
• Function of registers


  -Registers-Tiny, fastest memory within CPU with particular functions
• Function of PC

  -Program Counter- Holds Memory address of next instruction to be fetched (inside of the control unit)
• Function of accumulator

  -Accumulator- Stores data that is being used in or a result of processing

  (inside of the arithmetic logic unit)
• Function of MAR


  -Memory Address Register- Holds ANY memory address fetched or stored into memory (memory address is location of data in binary form)
• Function of MDR


  -Memory Data Register- Holds actual data/instruction to be fetched or stored into memory
• What is an embedded system


  -Computer that is part of another device
• What are properties of an embedded system


  Dedicated, cheaper, efficient, less programmable
• What is a GPE

  General Purpose Computer that can carry out many functions(programs)
• What is primary memory

  Significantly faster than secondary memory(allows memory to keep up with clock speed), but limited in size. Holds data currently in use
• What is RAM


  Primary, volatile memory that holds data currently in use by the CPU
• What is ROM

  Read only memory, non-volatile, not written to- stores info on how to boot up computer (BIOS)
• What is virtual memory

  Secondary Storage used when RAM is full
• What are the units used in a computer

  Binary. Lowest is a bit, 4 of these are a nibble and 8 are a byte
• What are the prefixes used for large amounts of data in binary

  kilo, mega, giga, tera, peta
• How do you differentiate abbreviations of bits and bytes in binary

  Capitalization of letter B
• What is a character set


  A standardized list of binary that equate to specific characters for use in a computer
• What are the 3 main character sets

  ASCII (7 bits + 1 error check) Extended ASCII (8 bits) Unicode (16 bits)
• What is lossy compression

  compression where data is removed e.g reducing colour/bit depth
• What is lossless compression


  compression where no data is lost. Removes redundant/simplifies data e.g RLE
• What is Compression


  Reducing the file size which helps in cases such as transferring data
• What is metadata


  Data about data-extra data that allows the data to be interpreted by a computer.
• What is a network


  Network-The connection of multiple devices- allows sharing of data and resources
• What is a LAN

  Local Area Network. Covers small area e.g 1 site/building. Hardware is owned by one org.
• What is a WAN

  Wide Area Network. Covers large area connecting LANs. Infrastructure is hired from telecoms companies
• What is a Client-Server Network

  -Files/software are stored on the central server and client computers make requests.
• What is a peer-to-peer network


  Each computer is connected directly to one another valued equally. Each peer is responsible individually.
• What are advantages/disadvantages of a client-server network

  Pros: Organised files/ manage security

  Cons: expensive to set up/maintain,reliant on server
• What are advantages/disadvantages of a peer-to-peer network

  Pros: Easy to maintain/no dependency on other devices

  Cons: hard to back up/ hard to keep track of files
• What is secondary memory

  Permanent, non-volatile memory that is used for long-term storage of data
• What are three types of storage

  Optical, Magnetic, Solid State
• What are the pros/cons of magnetic storage

  Pros: High capacity, cheaper than solid state

  Cons: slow speed and can wear/damage
• What are the pros/cons of solid state storage

  Pros: Durable due to no moving parts, very fast

  Cons: expensive, lower capacity than magnetic storage
• What are the pros/cons of optical storage

  Pros: Very portable and cheap(per GB)

  Cons: low capacity and slow speed
• What are the factors affecting performance of a network

  Bandwidth, No. of devices, Transmission Media, Signal Quality
• What is a star network

  All devices are connected to a central switch
• What is a mesh network


  All devices are connected to one another. Can be partial
• What are the pros/cons of star networks

  Pros: Network not affected by failure of one node/Easy to add devices

  Cons: Reliant on the switch,expensive or inconvenient