[PIC] does PIC take same machine cycle for all instruction??

[Deexith Hasan]

am i right PIC takes 4 clock pulses for 1 machine cycle and in PIC machine cycle = instruction cycle i.e all instruction takes one machine cycle?

is there any difference in machine cycle for RISC and CISC?

 

[FvM]

The Instruction Set chapter of the PIC reference manuals (e.g. PIC 16, PIC18) have a table "Instruction Set Summary" that answers your question. Some instructions are one cycle, some two or even three.

 

[Deexith Hasan]

if some instructions takes more than one cycle then whats the diff bet RISC and CISC

 

[betwixt]

There is a blurred area between the two. Generally, CISC instruction sets use shorter instruction words/bytes, the command and parameters are stored in adjacent addresses in the program memory. A RISC uses bigger instructions in which the parameter fields are embedded. The number of cycles is usually shorter in RISC systems simply because all the information to complete the operation is present in one instruction fetch whereas CISC may require several fetch cycles.

The actual clock cycles to execute an instruction has little to do with CISC/RISC, it depends on the internal architecture, pipelining, cache and use of clock phases.

Brian.