c4 - processor fundamentals Flashcards
describe the role of the registers in the FE cycle. [5]
The program counter holds the address of the nexxt instruction to be fetched and the contents are incremented. The MAR holds the address to fetch the data. The MDR holds the data pointed by the MAR. The instruction is transferred to the CIR to be decoded and executed.
When are interrupts detected? [1]
at the start/end of a FE cycle.
How are interrupts handled? [4]
first, priority is checked. if its a lower priority than the current process, the current process will continue, if its higher then the current process is put into a stack and the interrupt is handled by the interrupt service register (ISR). Once the ISR is finished, further interrupts are checked.
clock speed?
the number of FE cycles per second
what does more number of cores do?
more cores means more instructions can be carried out simultaneously.
how does bus width affect the performance of the computer?
allows the transfer of more data each time.
how does cache affect the performance of the computer?
the higher the capacity, the more frequently used instructions it can store for faster access.
what is meant by stored program concept?
instructions and data are stored in the same memory space.
What are the four flags?
Overflow, carry, negative and zero flags.
Describe the purpose of the control unit? [2]
To synchronize the actions of other components in the CPU. To send and receive control signals through the control bus. To control communication between the components and the CPU
What happens in the first pass in the two pass assembler?
- read the assembly code one line at a time.
- ignore comments
- Check the opcode is in the instruction set.
- Place address of labelled instruction in the symbol table.
What happens in the second pass in the two pass assembler?
- read the assembly code one line at a time.
- generate an object code from the symbol table generated in pass 1.
- save or execute the program.
Register transfer notation stages
PC <– [PC] + 1
MAR <– [PC]
MDR <–[[MAR]]
CIR <– [MDR]
What is relative addressing? [2]
mode of addressing in which the
memory address used is the current memory address
added to the operand.
how is data transmitted through a USB port? [1]
One bit is transferred at a time
