computer architectures jung h kim dept of systems engineering
TRANSCRIPT
Computer Architectures
Jung H Kim
Dept of Systems Engineering
Chapter1.Computing and Computers
Elements of Computers
(100-3)*2-(100-5)/3
BrainControl
Execute
Instruction
Data
Data Paper
Processor
MemoryControl
Execute
Input/ Output
Devices
Instruction
Data
Data
Every Computer Must Have the Following Components
1. A processor capable of control and execute programs.
2. A memory for saving programs and data.
3. A means of transferring information between the memory and a processor and between the computer and outside world.
Computation
Z = f(x)
in order to evaluate f(x), express x as a sequence of function(or instruction set)
f1, f2, … , fn
Y1 = f1(x)
Y2 = f2 (Y1)
:
:
Y n-1 = f n-1(Y n-2)
Z = f n(Y n-1)
Derived output
Given input
Limitation of Computers
1. The machine should not store the answers to all possible problems.
2. The machine should only be required to solve problems to which a solution procedure or a program can be given
3. It should process information at a finite time.
Touring Machine ( reasonable computing machine)
:A function f is computable if f(x) can be executed by any specified x in a finite number of steps.
… … MemoryX
P
Limitation of Computers
Unsolvable Problem
Goldbach’s conjecture
: Every even integer greater than 2 is the sum of exactly two prime number
such as 8=3+5 and 12=5+7.
It is not known if the conjecture is true for every even integer, nor is any
reasonable procedure known to determine whether the conjecture is true.
Limitation of Computers
Intractable Problem Factors : the nature of the given problem and computer power ) Example. Traveling sales problem
The brute-force approach : n! The best algorithm : exp(n)
Two questions in the difficulty of the algorithm
1.Space complexity : How much memory space is needed to execute it? 2.Time complexity : How much time is needed to execute it?
The VLSI Era
VLSI(Very Large Scale Integration)
LSI(Large Scale Integration)
MSI(Medium Scale Integration)
SSI(Small Scale Integration)
: profound impact on computer design and application
Current VLSI : photolithography technique
Ex)
CPU on a VLSI chip
Playstation 2 on a VLSI chip
Wafer scale integration( WSI )
The VLSI Era
CISC( Complex Instruction Set Computers )Intel 80x86, Motorola 680x0
: Execution of even a small percentage of complex instructions can reduce overall performance
RISC( Reduced Instruction Set Computers) IBM 6600/ SUN SPARC
Von Neumann bottle neck : CPU-memory speed disparity It takes CPU about 5 times longer to obtain a word from memory
than from one of internal registers -- how to reduce the bottle neck: cache memory, interleaved