4.4 Computer Componenets Flashcards
Components of Von Neumann Architecture:
ALU (Arithmetic and Logic Unit)
Control Unit (CU)
Registers
ALU:
Performs all of the arithmetic and logical operations of the CPU
Addition, Subtraction, etc/Comparisons/Boolean Operations
Control Unit:
Sends out control signals to the other parts of the CPU
Executes program instructions by following the fetch/decode/execute cycle
Made up of : 1. The clock – co-ordinates the CPU's activity 2. The decoder – decodes program instructions
Registers:
Tiny amounts of super-quick memory within the CPU
Used to hold information needed for the CPU to work
Each register holds a piece of information
What are the 4 registers:
Program Counter (PC)
Memory Address Register (MAR)
Memory Data Register (MDR)
Accumulator (ACC)
Program Counter:
Holds the memory of location address of the next instruction to be performed by the CPU
MAR:
Holds address of the location in memory where data is to be retrieved or stored
Accumulator:
Holds the result of the calculations and operations performed by the ALU
MDR:
Holds the data that has been retrieved from memory, or that is about to be stored in memory
Fetch:
- Address of the next instruction to be processed is copied from the Program Counter to the MAR
- The PC is incremented to point to the next instruction that will be needed when the cycle starts again
- The instruction stored at the location held by the MAR is copied to the MDR
Decode:
- The Control Unit decodes the instruction and sends control signals to the component within or outside the CPU that needs to act
Execute:
- The operation indicated by the instruction is performed by the appropriate component
Properties of Solid Storage:
High Speed
High Cost
Good Capacity
Good Reliability
Properties of Magnetic Storage:
Good Reliability
Low Cost
Low Speed
High Capacity
Properties of Optical Storage:
Low Cost
Great Reliability
Low Speed
Good Capacity
Properties of cloud:
No upgrades Easy Access Security Pricing Changes Risk of Privacy Internet Connection required
Application Software:
Helps a user of a computer system to complete a given task
System Software:
Controls hardware of the computer and provides an environment for application to run
Types of system software:
- Operating Systems
- Device Drivers
- Utility Software
Operating Software:
Manage access to the hardware in the computer
Utility Software:
Performs maintenance tasks to make sure the operation of the system continues
Device Drivers:
Small programs which tell the operating system how to use a piece of hardware
Transistors:
Electrical components made from semiconductor materials that can act as electrically-controlled switches. They can be used to temporarily store data (for example in some forms of primary storage)
Data Access in Solid Storage:
Data can be accessed randomly, This means that any piece of data can be accessed in a constant amount of time
This is achievable because there are no moving parts
Data Access in Magnetic Storage:
Data could be stored anywhere on the disk, and so to read/write data we first need to find the location on the disk
A magnetic read/write head is used to access the data while the platter spins
Data Access in Optical Storage:
A laser is shone on the disk surface
If the laser hits a pit, it is reflected elsewhere
If the laser hits a land, it will be reflect into a sensor
These can then be used to represent a 1 or 0
Data Storage in Solid Storage:
Solid state drives are made of flash memory
Flash memory stores the value of each bit in semi-conductor chip
Data Storage in Magnetic Storage:
The value of each bit of data (0 or 1) is represented as a positively or negatively charged magnetic particle
These particles are part of a magnetic disk called the platter
Data Storage in Optical Storage:
Each 1 or 0 (value of a bit) is represented as a microscopic hole – called a pit- or a flat surface – called a land – on the surface of the dis
