Structure and role of the processor and it's component Flashcards
What does the Arithmetic Logic Unit do?
Performs arithmetic and logical operations
What is the purpose of the Control Unit?
Supervises the fetch-decode-execute cycle, sends/receives control signals and decodes each instruction once it has been fetched from memory
What is the purpose of the clock?
To generate timing signals
What does a general purpose register store?
Any data
What is a dedicated register?
A register dedicated to holding specific data for a specific purpose
What is the purpose of the program counter?
Store the address of the next instruction.
What is the purpose of the current instruction register?
Stores the instruction currently being executed
What is the purpose if the memory address register?
Stores the data address of the item in memory being addressed. Could refer to instruction or data
What is the purpose of the Memory buffer register?
Stores data currently being fetched from memory
What is the purpose of the status register?
Stores the current state of the processor, such as whether an overflow has occurred
Describe the fetch part of the fetch-decode-execute cycle.
The clock tick starts cycle
The contents of the PC are copied to the MAR
PC is incremented by 1
Address bus transfers contents of MAR to memory
The data at that memory location is transferred to the processor via the data bus
The fetched data is stored in the MBR
The data is transferred to the CIR
Describe the decode part of the fetch-decode-execute cycle.
The data in the CIR is split into opcode and operand
Describe the execute part of the fetch-decode-execute cycle if data needs to be fetched from memory.
Address of data is stored in MAR
Address bus transfers contents of MAR to main memory
Data at that memory location is transferred to the processor via the data bus
Fetched data stored in MBR
What is an opcode?
An operation code that describes the operation that is to be performed
What is an operand?
The value in which the operation is to be carried out
What does addressing mode mean?
Whether it is an immediate or direct addressing
What is immediate addressing?
The operand is the value to be processed i.e. #3
What is direct addressing?
The operand is the address of the value to be processed i.e. R3
What is the purpose of using AND with the operation and 0?
It resets the register to 0
How can you find out if two values are equal?
Using an XOR and seeing if the results match
What is an interrupt?
A signal sent to the processor in order to alert an event
What is an Interrupt service routine (ISR)?
A program that examines an interrupt and handles it
What are some interrupt triggers?
timing signal
program error
hardware error
new I/O signal detected
When does interrupt checking occur?
After an instruction is executed
What happens if an interrupt is flagged?
The state of a processor is stored in the stack, and the source of the interrupt is identified, the appropriate interrupt service routine is called and the processor state is then restored
What is a single core?
A processor containing a single CPU
What is a dual core?
A processor containing two CPUs both working simultaneously
What is the cache?
A small unit of volatile memory containing the most frequently used instructions for fast access
What is the effect of increasing the number of cores?
More instructions can be processed simultaneously
What is the effect of increasing clock speed?
Instructions are processed quicker
What is a word in reference to binary data?
The maximum number of bits that can be processed in an instruction
What is the effect of increasing the address bus width?
More data in the main memory can be addressed
What is the effect of increasing the width of the data bu?
More data can be transferred in one fetch cycle, so less time is lost waiting for data to arrive at the processor
