1. Dr. Clincy Professor of CS
CS Chapter 1 (1 of 2)
Dr. Clincy
Professor of CS
Dr. Clincy
Lecture 3

2. Chapter 1 Objectives
Know the difference between computer organization and computer architecture.
Understand units of measure common to computer systems.
Appreciate the evolution of computers.
Understand the computer as a layered system.
Be able to explain the von Neumann architecture and the function of basic computer components.
Dr. Clincy

3. Ch 1- Introduction Why study computer organization and architecture?
Design better programs, including system software such as compilers, operating systems, and device drivers.
Optimize program behavior.
Evaluate (benchmark) computer system performance.
Understand time, space, and price tradeoffs in comparing systems.
Dr. Clincy

4. Ch 1 - Introduction What is Computer Organization ?
Encompasses all physical aspects of computer systems.
E.g., circuit design, control signals (how the computer is controlled), signaling methods, memory types.
Computer Organization helps us answer the question: “How does a computer operate ?”
What is Computer Architecture ?
Focuses on the structure and behavior of the computer system
Refers to the logical aspects of system implementation as seen by the programmer.
E.g., instruction sets, instruction formats, data types, number and types of registers, memory access methods, addressing modes, and I/O mechanisms.
The instruction set architecture (ISA) is the interface between the machine and all the software that runs on the machine
The “architecture” directly effects the logical execution of the programs
Computer Architecture helps us answer the question: “How do I design a computer?”
Not really clear-cut - Different perspectives of Org and Arch between Computer Scientists and Computer Engineers
Dr. Clincy

5. Ch 1 - Org Versus Arch
There is no clear distinction between matters related to computer organization and matters relevant to computer architecture.
Highlevel language algorithms are implemented by lower level languages which are implemented by machine-level algorithms implemented electronically
Principle of Equivalence of Hardware and Software:
Any task done by software can also be done using hardware, and any operation performed directly by hardware can be done using software.*
* Assuming speed is not a concern.
Dr. Clincy

6. Ch 1 - Computer Components
At the most basic level, a computer is a device consisting of three pieces:
A processor to interpret and execute programs
A memory to store both data and programs
A mechanism for transferring data to and from the outside world.
This course will explore these three major pieces/parts in some details
Before doing so, you will explore some terminology and history from the remainder of Ch 1 (online)
Dr. Clincy

7. Of the topics covered in Ch 1, will be examined over just (red):
Know the difference between computer organization and computer architecture.
Understanding units of measure common to computer systems.
Appreciate the evolution of computers.
Understand the computer as a layered system.
Be able to explain the von Neumann architecture and the function of basic computer components.
Dr. Clincy

8. Dr. Clincy Professor of CS
CS Chapter 2
Dr. Clincy
Professor of CS
Dr. Clincy

9. Chapter 2 Objectives
Understand the fundamental concepts of number systems.
Understand how computers add, subtract, divide and multiply
Understand the fundamental concepts of floating-point representation.
Gain familiarity with the most popular character coding systems.
Understand how data is encoded for transmission
Understand the concepts of error detecting and correcting.
Dr. Clincy

10. Introduction
A bit is the most basic unit of information in a computer.
Sometimes these states are “high” or “low” voltage or “on” or “off..”
A byte is a group of eight bits.
A byte is the smallest possible addressable unit of computer storage.
A word is a contiguous group of bytes.
Words can be any number of bits or bytes.
Word sizes of 16, 32, or 64 bits are most common.
In a word-addressable system, a word is the smallest addressable unit of storage.
A group of four bits is called a nibble.
Bytes, therefore, consist of two nibbles: a “high-order nibble,” and a “low-order” nibble.
Dr. Clincy

11. Positional Numbering Systems Review – Base 10 Numbers (Decimal)
Base-10
The decimal number system is based on power of the base 10. For example, for the number 1259,
the 9 is in the 10^0 column - 1s column
the 5 is in the 10^1 column - 10s column
the 2 is in the 10^2 column - 100s column
the 1 is in the 10^3 column s column
1259 is
9 X 1 = 9
+ 5 X 10 = 50
+ 2 X 100 = 200
+ 1 X 1000 = 1000
-----
1259
Dr. Clincy

12. Positional Numbering Systems Introducing Base 2 (Binary) and Base 16 (Hex) Number Systems
The Binary number system uses the same mechanism and concept however, the base is 2 versus 10
The place values for binary are based on powers of the base 2:
… 2^7 2^6 2^5 2^4 2^3 2^2 2^1 2^0
Base-16 (Hex)
The hexadecimal number system is based 16, and uses the same mechanisms and conversion routines we have already examined. The place values for hexadecimal are based on powers of the base 16
The digits for are the letters A - F (A is 10, …….., F is 15)
…….. 16^ ^ ^ ^0
Dr. Clincy

13. 5-bit Binary Number System
24, 23, 22, 21, 20
16, 8, 4, 2, 1
Dr. Clincy

14. Different Number Systems
Base-10 (Decimal) – what are the characters ?
Example = 659
Base-2 (Binary) – what are the characters ?
Example = 1101
Base-16 (Hex) – what are the characters ?
Example = AE
Base-8 (Octal) – what are the characters ?
Example = 73
Dr. Clincy

15. Converting Between Bases
Why Decimal, Binary and Hex ?
Give subscripts for Decimal, Binary, Hex, Octal
Dr. Clincy