System Architecture

System Architecture

1. Computer Components

   • CPU
     • This is the component that does all the calculations, processes and instructions that your computer needs.
     • CPUs are measured using...
       • The Clock speed, measured in GHz in most computers and MHz in smaller devices.
       • The amount of cores and threads it has, this means how many layers it has and how many things it can do at one.
       • The amount of different layers of cache it has[SRAM], in MB most of the time.
       • Certain features, like integrated graphics, or quick sync.
   • Memory
     • RAM (Random access memory) [DRAM]
       • The RAM stores the information that is currently used by programs running.
       • RAM is volatile, this means that once the power is cut, loses all of the information
       • RAM is measured using...
         • The capacity (amount), in GB for most computers, and MB for smaller devices.
         • The speed of the memory, measured in MHz.
         • The RAM timings.
         • The generation and type of memory (DDR2, DDR3, DDR4; DIMM, SODIMM...)
         • Whether you can use certain channel modes. (Duel, Quad channel)
     • ROM (Read only memory)
       • This is used to store the BIOS, which is very low level and contains information that controls the components to allow a computer to start up.
       • Found on the motherboard and the data on it is difficult to modify as it doesn't need to be changed most of the time.
   • Motherboard
     • This is the component which all the other parts either go onto it or connect to it.
     • Motherboards are usually measured in the features it has, what it supports, and built in functions it has, e.x. built in sound card, network card...etc.
   • Graphics Card
     • A graphics card process all the graphics displayed and handles the output to the monitor.
     • Graphics cards are measured in...
       • FLOPS (floating point operations per second), this measures the amount of floating-point calculations it can do per second.
       • The clock speed (MHz)
       • Size of the memory bus (bits) - the amount of memory it can address
       • The amount and generation of video memory is has[VRAM] (GB - GDDR4, GDDR5...)
       • The clock speed of the memory(MHz)
       • The bandwidth of the memory (GB/s)
       • RAMDAC speed [Random access memory digital-to-analog converter] (MHz)
       • The amount of power it draws (watts)
   • Storage
     • The storage of your computer is what stores the information that needs to be kept permanently.
       • User files
       • Program files
       • Operating system (OS)
     • Storage is measured in...
       • Capacity (GB, TB or PB at the moment)
       • Read and write speeds, in MB/s
       • Hard drives have a spinning disk, and each hard drive has a spin speed, measured in RPM.
       • SSDs have an amount of write cycles a part can change information for.
     • Types of storage
       • Hard drive (HDD)
         • Cheap and high capacity compared to SSDs.
         • Has moving parts
       • Solid State Drive (SSD)
         • Very fast, more durable.
         • Lower capacity, and quite expensive.
         • Does not have any moving parts.
         • Has a limit on write cycles.
   • Network Card
     • Enables a computer to connect to a network.
     • Network cards are measured using their bandwidth limit, normally in Gb/s. A typical one will have 1Gb/s, but more expensive ones will go up to 10Gb/s.

2. Embedded Systems

   • An embedded system is a small computer that has a very specific purpose, aka most things that need to keep track of the time, or preform a simple action.
   • Examples
     • Digital watch
     • Washing machine
     • Microwave
     • Traffic lights

3. CPU & Fetch Decode Execute

   • The fetch decode execute cycle is the basic operational process of a computer system.
   • Fetch
     • Fetch the instruction from the memory
   • Decode
     • Decode the instruction.
   • Execute
     • Perform the action/instruction.

4. Von Neumann Architecture

   • This is the modern architecture of how a CPU functions.
   • Parts
     • Control unit (CU)
       • MDR (Memory data register)
         • This gets the information that needs to be processed.
         • MAR (Memory address register)
           • This is what stores the location of the data so that the CPU knows where to put the information later.
       • This is the part that tells how all the other parts should respond to instructions.
     • Arithmetic and Logic Unit (ALU)
       • This is what is used to complete the instruction. If the instruction is a mathematical, it uses the Arithmetic, for example 2+5=?. If the instruction is a comparing instruction, it'll use the Logic unit, for example is 7=x, x=7.
       • Accumulator
         • This is used to quickly store the result of the instruction from the ALU.
     • Buses
       • This is what is connecting the different parts together, like the memory, to the CU, to the ALU, and the input and output devices.
     • Cache Memory
       • This is a super-fast memory used to store information that the CPU worked out.