Fundamentals of Computer Organisation and Architecture Flashcards
The Processor (CPU)
Executes program instructions to run applications
Main Memory
A data store for instructions for the processor that can be directly accessed
Read-Only-Memory (ROM)
Non-volatile memory which stores program instructions and frequently used data
Random-Access-Memory (RAM)
Volatile memory used to store data currently being processed by the computer
Address Bus
Transports memory addresses in a unidirectional path from the processor to the memory location
Data Bus
Transports data in a bi-directional path from the processor and main memory
Control Bus
Transports control signals from the processor to other components in a unidirectional path
Input/Output Controllers
Hardware that controls the communication of data between the processor and external components/devices like the monitor or mouse
Harvard Architecture
The processor will use two separate memory locations, one for the instructions and the other for the data
Von Neumann
The instructions and data are stored in the same memory which the processor can access
Arithmetic Logic Unit (ALU)
Part of the CPU where all arithmetic and logic operations are performed
Control Unit (CU)
Controls the components of the CPU
Registers
Small, temporary storage locations that have high read/write speeds
Program Counter (PC)
Register which holds the memory address of the next instruction to be executed in the fetch-decode-execute cycle
Memory Address Register (MAR)
Holds the address of the instruction that is going to be written/read from
Current Instruction Register (CIR)
Holds the instruction (data) that is currently being executed by the processor
Memory Buffer Register (MBR)
Hold the contents (data) of the memory location that is to be read from or that is to be stored
Clock
Part of the CPU which represents each fetch-decode-execute cycle that is performed and synchronises the components of the CPU and rest of the computer
Core
Represents how many fetch-decode-execute cycles that can be performed simultaneously
Cache Memory
Small amount of very fast memory inside the CPU
Opcode
Specifies the operation to carry out
Operand
The data on which the operation should be performed on
Addressing Modes (2 types)
Immediate Addressing - Value specified in the operand is treated as the actual value to be used
Direct Addressing - Value specified in the operand signifies the memory location which the value should be fetched from
What is meant by the term stored program concept
Instructions stored in main memory
Program run by fetching instructions in sequence
Program can be replaced by loading another program into memory
Contents of a main memory location can be interpreted as either an instruction or data
Principles of operation of a solid state drive (SSD)
Data is stored electronically
Data is stored in floating gate transistors
Prescence of trapped electrons return 0, absence is 1
NAND memory is used
Data is organised into blocks
Whole block of data must be written, not individual values
A block must be erased before it can be overwritten
Principles of operation of a laser printer
Bitmap image built in memory from page description
Negative charge applied to drum
Laser beam directed at drum
Mirror is used to direct laser
Where laser strikes, drum charge is neutralised
Negative charge applied to toner
Toner sticks to where laser struck
Paper passed over drum, toner is transferred to it
Positively charged transfer roller assists transfer of toner from drum to paper
Heater fuses toner unto paper
Advantages of RFID tags over Barcode Labels
RFID tags can be read from a further distance
They can be read at a faster rate
Are less easily damaged
Don’t have to spend time added barcodes to products
Advantages of Barcode Labels over RFID Tags
Barcodes are cheaper
Less electronic waste
Not susceptible to radio interference
Barcode Scanners
They send out lasers which can then detect the light and dark areas of the barcode, representing binary values as a result
Digital Camera
Has a CCD sensor which captures millions of points of light using sensors arranged in a grid. Each sensor measures the intensity of the light and records it as an electronic value. This is performed through a red, blue and green Bayer mosaic filter so they can get 3 separate readings to reproduce the colour
RFID Tag (Active and Passive)
Consists of a tiny radio transponder, a radio receiver and transmitter
Active - Have a power supply that they use in order to transmit signal at a greater distance
Passive - Don’t have a power supply and are powered by the radio waves sent out by reader when they are close
