System Architecture/System Memory/Storage

System Architecture/System Memory/Storage

1. Cpu

   • ALU
     • The Arithmetic Logic Unit (ALU) is a digital circuit used to perform arithmetic and logic operations.
   • Control Unit
     • The control unit is a component of a computer's central CPU that directs the operation of the processor. It tells the computer's memory, arithmetic/logic unit and input and output devices on how to respond to a program's instructions.
   • Fetch-Decode Execute Cycle
     • First, it gets an instruction from main memory (Fetch) Then, it determines what the instruction is trying to do (Decode) Finally, it carries out the instruction and tells other components what to do depending on the instruction (Execute) An optional step that might happen is store some information in the RAM if needed (Store)
   • Register
     • A processor register is a quickly accessible location available to a computer's CPU. Registers usually consist of a small amount of fast storage, although some registers may have specific hardware functions, and may be read-only or write-only.

2. Memory

   • Volatile
     • Needs power for the information to be retained, clears it self after computer turns off
       • Useful if you don't want the data to stay there forever but you want to use it temporarily to do certain tasks such as program data for programs to work
     • Example: RAM
   • Non-Volatile
     • Example: Hard Drive & ROM
     • It retains it's data even if there is no power
       • Useful if you are storing data that you need even if there is no power or that is needed by the computer to perform functions such as turning the computer on

3. Storage

   • Types
     • Magnetic
       • Uses magnetic fields to create bumps on the drive, a bump would be a 1 and nothing would be a 0. To read or write a read/write head physically needs to move around the platter and read the bumps on the drive.
         • This can store a lot of data because it uses small bumps and magnetic fields so it can store a lot more than optical storage
     • Solid-State
       • Uses semiconductor chips to store information on the drive. It uses electrical signals to write or read the chips on the SSD
         • This is very fast compared to hard drives because on the HDD to write or read the head physically needs to move but for SSD it happens very fast because it is done through electrical signals instead.
     • Optical
       • Data is written to a disc using a laser, then another laser is used to read the disc
         • They don't store that much data though and are quite slow reading and writing it

4. Memory

   • Cache
     • Temporary place to store information that is needed quickly like game data, while playing a game, or web pages
     • This can be part of the CPU, RAM, storage disk.
   • Virtual Memory
     • This is a part of the storage disk which is reserved as extra memory in case the RAM gets full, this is so the computer won't crash and acts like secondary RAM but is way slower than RAM even if the storage disk is an SSD

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