1. CCSE251 Introduction to Computer Organization
Overview

2. What is Computer Organization about?
refers to the level of abstraction
above the digital logic level, but
below the operating system level.
At this level
the major components are
functional units or subsystems
that correspond to specific pieces
of hardware (e.g., memory, register)
built from the lower level building
blocks (e.g., logic gates)
How does a computer work???

3. Why Study Computer Organization?
Gain an understanding of the underlying implementation of code.
pointers, memory usage, code constructs
Design better programs.
including system software such as compilers, operating systems, and device drivers.
Learn important computer science concepts.
dual between hardware and software
Optimize program behavior.
Understand time, space, and price tradeoffs.
hardware or software decisions?

4. Principle of Equivalence of Hardware and Software
Anything that can be done with software can also be done with hardware, and anything that can be done with hardware can also be done with software.
Assumes speed and cost are not a concern.
Hardware is almost always faster and more expensive.

5. Computer Components
At the most basic level, a computer is a device consisting of three pieces:

6. Computer Level Hierarchy
A hierarchical design divides a computer system into manageable layers.
Each layer can be implemented without intimate knowledge of the other layers.
Each layer is an abstraction of the level below it.
Each layer executes their own particular instructions, calling upon lower layers to perform tasks as required.
Computer circuits ultimately carry out the work.

7. Computer Level Hierarchy

8. Computer Level Hierarchy
Level 6: User
Program execution and user interface level.
The level with which we are most familiar.

9. Computer Level Hierarchy
Level 5: High-Level Language
The level with which we write programs in languages such as C, Pascal, Lisp, and Java.

10. Computer Level Hierarchy
Level 4: Assembly Language
Acts upon assembly language produced from Level 5, as well as instructions programmed directly at this level.

11. Computer Level Hierarchy
Level 3: System Software
Controls executing processes on the system.
Protects system resources.
Inserts system library code.
Assembly language instructions often pass through Level 3 without modification.

12. Computer Level Hierarchy
Level 2: Machine
Also known as the Instruction Set Architecture (ISA) Level.
Consists of instructions that are particular to the architecture of the machine.

13. Computer Level Hierarchy
Level 1: Control
A control unit decodes and execute instructions and moves data through the system.
Internal to the microprocessor and can be microprogrammed or hardwired.

14. Computer Level Hierarchy
Level 0: Digital Logic
This level is where we find digital circuits (the chips).
Digital circuits consist of gates and wires.
These components implement the mathematical logic of all other levels.
Note: Gates are abstractions of actual hardware.

15. We are going to cover

16. von Neumann Model
von Neumann computers have the following characteristics:
Three hardware systems:
A central processing unit (CPU)
A main memory system
An I/O system
The capacity to carry out sequential instruction processing.
A single data path between the CPU and main memory.
This single path is known as the von Neumann bottleneck.

17. von Neumann Architecture
This is a general depiction of a von Neumann system:
These computers employ a fetch-decode-execute cycle to run programs as follows . . .

18. von Neumann Architecture
The control unit fetches the next instruction from memory using the program counter to determine where the instruction is located.

19. von Neumann Architecture
The instruction is decoded into a language that the ALU can understand.

20. von Neumann Architecture
Any data operands required to execute the instruction are fetched from memory and placed into registers within the CPU.

21. von Neumann Architecture
The ALU executes the instruction and places results in registers or memory.

22. History of Computing Devices
Generation Zero: Mechanical Calculating Machines ( )
First Generation: Vacuum Tube Computers ( )
Second Generation: Transistorized Computers ( )
Third Generation: Integrated Circuit Computers ( )
Fourth Generation: VLSI Computers (1980-present)

23. Generation Zero: Mechanical Calculating Machines (1642-1945)
Calculating Clock - Wilhelm Schickard ( ).
Pascaline - Blaise Pascal ( ).
Difference Engine - Charles Babbage ( ), also designed but never built the Analytical Engine.
Punched card tabulating machines - Herman Hollerith ( ).

24. Generation Zero: Mechanical Calculating Machines (1642-1945)
Charles Babbage
Analytical Engine
Started in 1834
Never finished
No Hertz Rating

25. First Generation: Vacuum Tube Computers (1945-1953)
Atanasoff Berry Computer ( )
John Atanasoff and Clifford Berry of Iowa State University
solved systems of linear equations.
Electronic Numerical Integrator and Computer (ENIAC) (1946)
John Mauchly and J. Presper Eckert of University of Pennsylvania
First general-purpose computer.

26. First Generation: Vacuum Tube Computers (1945-1953)
Eckert and Mauchly
18,000 Vacuum tubes
1,800 instructions/sec
3,000 ft3

27. Second Generation: Transistorized Computers (1954-1965)
IBM 7094 (scientific) and 1401 (business)
Digital Equipment Corporation (DEC) PDP-1
Univac 1100
Control Data Corporation 1604
. . . and many others

28. Third Generation: Integrated Circuit Computers (1965-1980)
IBM 360
DEC PDP-8 and PDP-11
Cray-1 supercomputer
. . . and many others
By this time, IBM had gained overwhelming dominance in the industry.
Computer manufacturers of this era were characterized as IBM and the BUNCH (Burroughs, Unisys, NCR, Control Data, and Honeywell).

29. Fourth Generation: VLSI Computers (1980-present)
VLSI (very large scale integration) enable more than 10,000 components per chip.
The first was the 4-bit Intel 4004.
first microprocessor
Later versions, such as the 8080, 8086, and 8088 spawned the idea of “personal computing.”

30. Fourth Generation: VLSI Computers (1980-present)
Intel 8086
29,000 transistors
33 mm2
5 MHz
Introduced in 1979
Basic architecture of the IA32 PC

31. Fourth Generation: VLSI Computers (1980-present)
Pentium
3,100,000 transistors
296 mm2
60 MHz
Introduced in 1993
1st superscalar implementation of IA32

32. Multi Core Processors A single chip has multiple processing units
Dual core has 2 processing units
Quad core has 4 processing units
Allows multiple programs to be executed at once.
Programs can also take advantage of multiple processing units.
Software must be specifically designed to do this.
Software is hard to write
Faster than having multiple processors (each on a separate chip)
Processing elements are “closer”
Communication off-chip is slow

33. What next?
Enormous improvements in computational power require departure from the classic von Neumann architecture.
Possible 5th generations?
A computer that would use artificial intelligence techniques to learn, reason, and converse in natural languages resembling human languages.