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Showing posts from February, 2014

Difference between CISC and RISC Architecture

CISC| Complex instruction set Computing.
1.very large instruction sets reaching up to and above three hundred seperate instructions.
2. Performance was improved by allowing the simplification of program compilers, as the range of more advanced instructions available led to less refinements having to be made at the compilation process. However, the complexity of the processor hardware and architecture that resulted can cause such chips to be difficult to understand and program for, and also means they can be expensive to produce.
3. more specialized addressing modes and registers also being implemented, with variable length instruction codes.
4. Instruction pipelining can not be implemented easily.

5. Many complex instructions can access memory, such as direct addition between data in two memory locations. 

6. Mainly used in normal PC’s, Workstations and servers.

7. CISC systems shorten execution time by reducing the number of instructions per program.

8. Examples of CISC Processors: Intel x…

8085 architecture

Acumulator:-It is a 8-bit register which is used to perform arithmetical and logical operation. It stores the output of any operation. It also works as registers for i/o accesses.

Temporary Register:-It is a 8-bit register which is used to hold the data on which the acumulator is computing operation. It is also called as operand register because it provides operands to ALU.

Registers:-These are general purposes registers. Microprocessor consists 6 general purpose registers of 8-bit each named as B,C,D,E,H and L.   Generally theses registers are not used for storing the data permanently. It carries the 8-bits data. These are used only during the execution of the instructions.
These registers can also be used to carry the 16 bits data by making the pair of 2 registers. The valid register pairs available are BC,DE HL. We cannot use other pairs except BC,DE and HL. These registers are programmed by user.

ALU:-ALU performs the arithmetic operations and logical operation.

Flag Registers:-It…