8a: Internal hardware components Flashcards
what is the stored program concept
- the program the proccesser is executing is kept in main memory along with the data the program needs
- the processer fetches one instruction at a time (serially) from main memory and executes it
explain the role of the processer
- executes instructions and controls the operation of all components
- executes instructions by repeating 3 operations: Fetch Decode Execute
what is the role of the main memory
- holds the current programs that are being executed
- hold current data being processed
- temporary memory: loses its contents when the computr turns off
what is the role of the secondary memory and give examples
- permanent storage of data and programs
- eg, HDD and CD drive
what are the 3 different buses
- address
- control
- data
describe and explain the control bus
- bi-directional bus
- used to transmit command, timing and specific status information between system components
- timing signals ensure that the various components operate in synchrony
- command signals specificy operations to be performed
- status signals indicate information about how things are going, like wether a task is done or not
explain the following control lines:
1. memory write
2. memory read
3. I/O write
4. I/O read
5. bus request
- causes data on data bus to be written to addressed location
- causes data from addressed location to be placed on data bus
- causes data on data bus to be output to the addressed I/O port
- caused data from the addressed I/O port to be placed on the data bus
- indicates a component needs to gain control of the system bus
describe and explain the data bus
- typically consists of 8, 16 or 32 seperate lines
- bi-directional line for moving data and instructions between system components
explain the importance of the width of the data bus
- width of data bus is a key factor to determing overall system pecformance
- if data bus is 8 bits wide and each instruction is 16 bits long then the processor must access main memory twice during each instruction cycle
explain the address bus
- when the CPU needs to read or write data, it uses the address bus to specify the memory location its interested in
- the width of the address bus determins the maximum amount of memory the computer can access
- the CPU uses the adress bus to fetch instructions and data from memory, enabling the execution of tasks
what are five factors affecting processors performance
- width of address bus
- multicore processor
- clock
- word length
- cache memory
full explanation
explain the steps of the fetch execute cycle
- the contents of the program counter (the adress of the next instruction) is placed into the memory address register
- the adress is sent from the MAR along the adress bus to the main memory. The instruction at that adress is found and returned along the data bus to the memory buffer register
- at the same time the contents of the program counter is increased by 1, to reference the next instruction to be executed
- the MBR loads the current instruction register with the instruction to be executed
- the instruction is decoded an executed
what are the 2 different types of architecture
- Von Neumann
- Harvard
compare Von Neumann architecture to Harvard architecture
- VN is an ancient computer architecture whereas H is modern
- Vn has same physical memory address for instructions and data whereas H has seperate physical memoy adresses for instructions and data
- in Vn two clock cycles are required to execute a single instruction whereas in H a single cycle is needed
- VN is cheaper
give the definition for:
processor
a device that carries out computation data by following instructions
