Basic Introduction of CISC & RISC for Embedded Engineers

Sr.No 1	CISC Founded in 1970’s	RISC Founded in late 1980’s
2	Needed more number of clock cycles	Designed to work with less or limited number of clock cycles. Usually 1 clock.
3	These had slow memories coupled to processor built using many simple IC’s.	Could be coupled with faster memories
4	The processor was controlled by microcode ROM’s, which were faster than processor.	The processor itself was faster and interfacing other interface did not much affect the overall speed.
5	Code can execute X86 machines code	Code cannot execute code for X86
6	Older CISC did not support pipeline	Supports pipelining
7	Variable Instruction length	Fixed instruction length.
8	Allows value in memory to be used as operands for data processing	Can work only if data is in registers and not in memory directly.(LOAD & STORE )
9	Have very good code density	Have very poor code density.
10	Hardware complexity is less	Hardware complexity is more.

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