CS 1.1 Processors

• Harvard Architecture - A computer architecture which is more modern than VNM. Has separate RAM for instructions and data and different buses for both. It can therefore do both at the same time, as is faster and more expensive.
• Von Neumann Architecture (VNA) - A computer architecture that stores all programs, data, and instructions in one memory location
• CPU Pipelining - While one instruction is being fetched, another is being decoded, another executed.
• Control Unit - coordinates the activities of the CPU and the memory.
• The ALU - Arithmetic Logic Unit - performs arithmetic and logic operations on data.
• The PC - the program counter is used to store the address of the next instruction to be executed.
• Registers - small storage areas within the processor where data can be stored temporarily while it's being processed by the CPU.
• Cache Memory - a high-speed temporary store used to speed up access to frequently accessed data or instructions.
• The MDR - Memory Data Register holds the contents of the memory location specified by the MAR.
• The MAR - Memory Address Register contains the address of the operand or result of an operation.
• The CIR - Current Instruction Register holds the current instruction being processed by the processor.
• Data Buses - A type of bus that carries data between components of a computer system.
• Address Buses - A bus that carries data between the CPU and the memory.
• Control Bus - A bus that carries control signals between the CPU and the peripherals.
• Clock speed - the number of thousands of FDE cycles per second that a CPU can perform.
• ROM:-Read Only-Small capacity-Hard to modify-Non volatile-Used to store BIOS
• RAM: Random access memory, stores currently used programs and data, write/read speed faster than ROM, faster access than SS, volatile.
• RAM and ROM, both primary storage/main memory. Both allow random access. Both can store programs. Connected to CPU via buses
• Pipelining - Breaking a process into chunks that can be run concurrently
• Interrupt - An event external to the currently executing process that causes a change in the normal flow of instruction execution eg printer out of paper.
• Interrupt Service Routine: A particular routine that is run to service an interrupt.
• GPU is a device which unlike CPUs has lots of independent processors which work in parallel making it very efficient at completing repetitive tasks such as image processing and machine learning.
• SS-Secondary Storage-Slowest access time-Holds large amounts of information-Non volatile
• Reduced Instruction Set Computers (RISC) In these processors, there is a small instruction set. Each instruction is approximately one line of machine code and takes one clock cycle.
• Complex Instruction Set Computers (CISC) In these processors there is a large instruction set. The aim is to try and accomplish tasks in as few lines of assembly code as possible. These instructions are built into the hardware, and are used in embedded systems.
• RISC Processors:

  The compiler has to do more work to translate high level code into machine code.

  More RAM is required to store the code.

  Pipelining is possible since each instruction takes one clock cycle.
• CISC Processors:

  The compiler has less work to translate high level code into machine code.

  Less RAM is required since code is shorter.

  Many specialised instructions are made, even though only a few of them are used.
• Multi-core CPUs have multiple independent cores that can complete instructions separately which results in higher performance.
• Parallel systems complete tasks like a multi-core system, however instead of requiring multiple cores they can complete tasks with a single core.
• Input devices include: ○ Keyboards ○ Webcams ○ Magnetic stripe readers ○ Barcode readers ○ Touch screens
• Output devices include: ○ Speakers ○ Printers ○ Projectors
• Performance factors for both input and output devices include: ○ Speed ○ Accuracy ○ Cost ○ Relevance to task
• Optical devices - Read from and written to using lasers:

  CD - Small storage size, portable, not durable

  DVD - Larger small storage size, portable, not durable

  Blu-Ray - More storage, same drawbacks.
• Solid state drives (SSD): No moving parts, faster than HDD, more reliable, less power consumption, smaller form factor, no noise, but more expensive per gigabyte.
• Hard disk drive (HDD) - Uses spinning disks to read/write data, larger storage capacity, slower access times, cheaper per gigabyte, more fragile, louder, heavier, and requires more power.
• Virtual Storage - The remote storing of data over the internet, include cloud storage and networked storage . Is limited by network speeds and cost.