SCSC 311 Information Systems: hardware and software. Objectives. CPU execution cycle CPU instructions Instruction format CPU design: CISC vs. RISC CPU registers Enhancing CPU performance The limitations of semiconductor-based microprocessors. Review: CPU Components. Control unit
SCSC 311 Information Systems: hardware and software
A complex chain of events occurs when CPU executes a program.
Q: how would the control unit accomplish this?
Q: what happens when an executing program halt?
Six Data Transformation Instructions
Q: What can a logic SHIFT instruction do?
Ans: A logic SHIFT instruction can extract a signal bit from a bit string.
Arithmetic SHIFT instructions perform multiplication or division.
Q: Why include these complex instructions in CPU instruction set?
(1) A 20-bit instruction uses register inputs and output:
8-bit Op code, 3 4-bit operands store register numbers
(2) A 32-bit load and store instruction:
8-bit Op code, 2 4-bit operands, 1 16-bit operand
do more work per instruction each complex instruction require less memory and execution time
Apples’ power Macintosh and some version of Linux are implemented based on RISC processor
Win OS are implemented based on CISC processor
e.g. c = a * b
Q 1: Which CPU design is better ?
Q 2: Why does Intel use CISC design?
Q: Why is that?
Q: why is that?
E.g.,: Doubling word size generally increases the number of CPU components by 2.5 to 3 times
Q: A computer has clock rate 5 GHz, what is CPU cycle time?
Q: How to enhance the performance of a computer system ?
It is difficult to fully realize the theoretical
improvement of pipelining
e.g. Sun UltraSparc CPU duplicates ALU, Registers
(The symbols of gates are not required.)
Addition circuit: combines a half-adder and an array of full adders
(The detailed layout is not required.)
Moore’s Law: rate of increase in transistor density on microchips
doubles every 18-24 months with no increase in unit Cost
Q1: Does Rock’s Law mean CPUs are becoming more expensive?
Q2: Would Moore’s Law always be true?