Differentiate between CISC and RISC processors.
Differentiate between CISC and RISC processors:
The difference between CISC and RISC processors is as follows:
CISC:
1.CISC instructions utilizes more cycles.
2.It has more complex instructions.
3. Its implementation is slower.
4.It is typically used in personal computers.
5.It uses more power.
RISC:
1.RISC instructions utilizes less cycles.
2.It has less complex instructions.
3. Its implementations is faster than CISC.
4. It is typically used in tablets and smartphone etc.
5. It uses less power.
Pipelining:
Pipelining is a technique in which CPU fetches the next instruction before it completes the machine cycle for the first instruction. Modern computers use pipelining technique to process multiple instructions at the same time. It result in faster processing and increases the performance of the computer.
Without pipelining, the processor fetches, decodes, executes and stores only one instruction at a time. The CPU waits until instruction completes its all four stages and then executes the next instruction.
Registers:
A register is a small high speed memory inside CPU. The CPU contains a number of registers. Registers are used to store information being processed. These are temporary storages areas for instructions or data. The temporary results during processing are also stored in registers. Each register has a predefined function.
Register size determines how much information it can store. The size of register is in bytes. Each byte can store one character of data. A register can be of 1,2,4 or 8 bytes. Bigger size of register increases the performance of CPU.
Control unit messages registers for the following purposes:
- Input the instructions or data.
- Store the instructions or data.
- Transfer the instructions or data.
- Perform arithmetic or logical operations at high speed:
Memory Address Register (MAR):
The memory address register is used to store memory address being used by the CPU. CPU stores the address of memory location in this register in order to read or write data to it.
Memory Buffer Register (MBR):
The memory buffer register is used to store data coming from the memory or going to the memory. It act as a small memory buffer. It ensures that the processor and memory work without being affected by any difference in operation.
Program Counter (PC):
The program counter is used to control the sequencing of the execution of instructions. It stores the address of the next instruction to be fetches for execution. The value of program counter is loaded into next instruction to be fetches the instruction from the memory. The value of program counter increment when the instruction is fetched. It now points to the next instruction.
Instruction Register (IR):
The instruction register is used to store the instructions that are fetched from memory for execution. An instruction register holds the instructions to be decoded by the control unit. The timing and control logic sequence of signals to execute the instructions.
General purposes Register:
General purpose register are used in mathematical and logical operations. These registers are part of ALU. Different general purpose registers as follows:
Accumulator Register:
It is used for arithmetic and data operations.
Base Register:
It is used for arithmetic and data movement. It has special addressing capabilities.
Counter Register:
It is used for counting purpose. It acts as a counter for repetitions or loops.
Data Register:
It is used for division and multiplications.
The size of these registers can be 1 to 4 bytes. The two bytes data registers AX,BX, CX, DX contain two parts of 8-bit size. These parts are separately accessible. The lower order bytes are AL, BL, CL and DI . The high order bytes are AH, BH, CH and DH . The modern processors use the registers of 4 bytes (32bits) known as EAX, EBX, ECX and EDX.
Address or Segment Registers:
coming soon...................
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