COMPUTER SCIENCE REVISION

COMPUTER SCIENCE REVISION

1. The VN architecture

   • Method for Input and Output
   • Registers
     • MAR
       • Memory Address Register
     • PC
       • Program Counter
     • CIR
       • Current Instruction Register
     • MDR
       • Memory Data Register
     • ACCUMLATOR
   • ALU (Arithmetic Logic Unit)
   • Buses
   • CU (Control Unit)
   • Memory
   • Another name for the VN architecture is stored program architecture

2. SECONDARY STORAGE

   • Optical
     • Optical storage uses lasers to read data.
     • Optical memory is quite cheap.They are also quite reliable as they last quite a long time.They are easy to move around and don't need a cooler.They are relatively slow but can hold plenty of data.
     • EXAMPLES
       • DVD'S
       • CD'S
       • BLU-RAY
     • 25GB is 44p
   • Magnetic
     • Magnetic memory uses different magnetisms on a disk to show data.We use this by saying whether it is on or off
     • Magnetic memory is very reliable however will need a cooler as it gets very hot. It is very cheap and it's quite fast although it's not at all portable.
     • Examples
       • Hard Disk Drive
       • Magnetic Tape
       • Floppy Disk Drive
     • 3TB £85
   • Solid State
     • EXAMPLES
       • USB stick
       • Solid State Drive
     • Solid State Drive's are portable and overall the best type of secondary memory.they are very fast, durable and very reliable however it is also the most expensive type of secondary storage.

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