Data- Path Design:- Capabilities and performance characters of principals functions units(FU's).
Example:- Registers, ALU, Shifters, Logic Units, etc.
Data-path design is the way in which these components are interconnected.
Example:- Buses connections, Multiplexers, etc.
It describes how information flows between components.
Control-Path Design:- It describes logic & means by which such information flow is controlled.
It also tells control & coordination of FUs.
-> Design methodology depends both upon data-path & control-path design.
-> It also depends on CPU execution time & inturn CPI(Clock per instruction)
-> If CPI=1, CPU will be RISC CPU i.e single cycle execution of each instruction as MIPS(Millions of instruction per second) machine or Load/Store architecture.
-> If CPI>1, CPU will be CISC CPU as Intel's 8085/8086 & so on.
-> If CPI<1, CPU will be advanced processor like vector array,
RISC Design:- It is single cycle processor.
(i) It is faster, but difficult to design.
(ii) Advantage:- one clock per instruction.
(iii) Disadvantage:- long cycle time.
(iv) It is based on hardwired architecture.
CISC Design:- It is multiple cycle processor.
(i) It is slower, but simple to implement.
(ii) It is based on micro-programming design style & flexible in nature.
(iii) It has short cycle time.
Design is described in terms of components and how they have been assembled.