1.1 Hardware Flashcards
What is the CPU?
The core of the computer.
What are the main components of the CPU?
- Control unit (CU)
- Arithmetic logic unit (ALU)
- Registers
What is the purpose of the CU?
Manages and coordinates CPU operations.
What is the purpose of the ALU?
Performs arithmetic and logical operations.
What are registers?
Fast storage locations within the CPU.
What is the Current instruction register (CIR)?
Holds the instruction currently being executed.
What is the memory address register (MAR)?
Stores the address of the memory location to be accessed.
What is the memory data register (MDR)?
Contains data being transferred to or from memory.
What is the Accumulator?
Stores intermediate results of arithmetic and logical operations.
What is the address bus?
Carries memory location addresses.
What is the data bus?
Transfers data between CPU and memory.
What is Random Access Memory (RAM)?
Volatile main memory.
What is Von Neumann Architecture?
Common processor design with shared storage for data and instructions; less expensive but slower.
What is Harvard architecture?
Processor design with separate storage for data and instructions; more expensive but faster.
What is the FDE cycle?
The Fetch-Decode-Execute (FDE) cycle, also known as the instruction cycle, is a fundamental process in computer architecture that describes how a computer’s central processing unit (CPU) operates. This cycle is continuously repeated as the computer processes instructions.
What happens during the fetch stage?
- The CPU retrieves the next instruction from the computer’s memory.
- The Program Counter (PC) contains the address of the next instruction to be fetched.
- This address is copied into the Memory Address Register (MAR).
- The instruction at that memory address is then copied into the Memory Data Register (MDR).
- Finally, the instruction is placed in the Current Instruction Register (CIR).
- The Program Counter is then incremented to point to the next instruction.
What happens during the decode stage?
- The Control Unit (CU) of the CPU interprets the instruction in the CIR.
- It determines what operation needs to be performed (e.g., addition, subtraction, data movement).
- The CU identifies the memory locations or registers that contain the required data (operands).
- It also determines where the result should be stored.
What happens during the execute stage?
- The CPU carries out the instruction that was decoded.
- If it’s an arithmetic or logical operation, the Arithmetic Logic Unit (ALU) performs the calculation.
- For data movement operations, data is transferred between registers or between memory and registers.
- The result of the operation is stored in the designated location (usually a register or memory address).
What factors effect computer performance?
Clock speed, Cache size, Number of cores
What is the clock speed?
An alternating pulse of low and high voltage, measured in Hz/GHz. A higher clock speed results in faster processing.
What is cache memory?
A fast but small-capacity set of locations close to the processor. It stores frequently used instructions and data. Measured in megabytes, cache memory is more expensive than RAM.
What are the different levels of cache memory and how do they effect performance?
Level 1 cache: The smallest and fastest cache, integrated into the circuitry of each core.
Level 2 cache: Often shared by cores, it’s larger but slower than L1 cache.
Level 3 and 4 cache: Slower than L2 cache but larger, located on the processor or nearby on the motherboard.
How do the Number of cores effect the performance?
Number of cores: Each core contains a Control Unit (CU), Arithmetic Logic Unit (ALU), special registers, and local cache. As each core can run its own Fetch-Decode-Execute (FDE) cycle, more cores allow for more instructions to be processed simultaneously.
What is a input device?
A device that sends data to the computer for processing.
What is a output device?
A device that presents the results of the processing.
What does the term contemporary mean?
Relating to modern or present-day technology.
What are the 3 types of computer secondary storage?
Magnetic, Optical, Solid state
What does media mean in terms of storage?
Media: The physical component where data is actually stored.
What is a Hard disk drive?
Hard disk drive (HDD) – A form of secondary storage that uses magnetism to write and read data based on positive or negative charges.
What are the different components of a Hard disk drive?
- Read and write head – Writes data by applying magnetic charges to different sectors and reads data by detecting these charges. The different charges represent binary 1s or 0s.
- Disk – Made of metal or coated with a magnetic material. Several disks are stacked within the HDD.
- Actuator arm – Moves the read and write head across the disk, allowing access to the entire surface.
What is Defragmentation?
Defragmentation – A process used when an HDD has been heavily used and data becomes fragmented, slowing access speeds. Defragmentation software reorganises and rewrites the data to improve performance.
Properties of Magnetic storage?
- Brittle
- High capacity
- Has moving parts
- Can be written indefinitely
- Uses defragmentation
What is a Optical disk?
Optical disks – These are storage devices that use pits and lands on their surface to represent data, which is read by reflecting a laser off the disk.
What are the pits?
Pits – Indentations in the disk’s aluminium layer that refract the laser light. The sensor interprets this as either a 0 or 1.
What are the lands?
Lands – Flat areas on the disk where the laser light is reflected directly. The sensor reads this differently from pits, allowing for binary data representation.
Properties of optical storage?
- High capacity
- Brittle
What is the drive in solid state storage?
Drive: The device that reads and writes data from secondary storage.
What is flash memory?
Flash memory: Uses integrated circuits in a chip comprised of billions of transistors.
What is a transistor?
Transistor: A tiny electronic device capable of controlling the flow of electricity.
What is a floating gate?
Floating gate: Has two oxide insulating layers which can restrict the flow of electricity, trapping electrons. The state remains even without power.
Properties of solid state storage?
- Durable
- Fast speeds
- Very expensive
- Limited write cycle—high number but will eventually max out.
