Tecnologia

Einstein College of Engineering

EINSTEIN COLLEGE OF ENGINEERING

Computer Architecture and
Organization
Lecture Notes-EC53
SUJATHA.K & JASMINE MARY.S

TEXTBOOKS:
1. John P. Hayes, ‘Computer architecture and Organisation’, Tata McGraw-Hill, Third
edition, 1998.
2. V. Carl Hamacher, Zvonko G. Varanesic and Safat G. Zaky, “ Computer
Organisation“, V edition, McGraw-Hill Inc, 1996.Einstein College of Engineering

UNIT 1
INTRODUCTION
FUNCTIONAL UNITS OF A COMPUTER SYSTEM
Digital computer systems consist of three distinct units. These units are as follows: Input unit Central
Processing unit Output unit these units are interconnected by electrical cables to permit communication
between them. This allows the computer to function as a system. Input Unit A computer mustreceive both
data and program statements to function properly and be able to solve problems. The method of feeding data
and programs to a computer is accomplished by an input device. Computer input devices read data from a
source, such as magnetic disks, and translate that data into electronic impulses for transfer into the CPU.
Some typical input devices are a keyboard, a mo use, or ascanner. Central Processing Unit The brain of a
computer system is the central processing unit (CPU). The CPU processes data transferred to it from one
of the various input devices. It then transfers either an intermediate or final result of the CPU to one or more
output devices. A central control section and work areas are required to perform calculations or manipulate
data. The CPU is thecomputing center of the system. It consists of a control section, an arithmetic-logic
section, and an internal storage section (main memory). Each section within the CPU serves a specific
function and has a particular relationship with the other sections within the CPU.

CONTROL SECTION
The control section directs the flow of traffic (operatio ns) and data. It also maintains order within thecomputer. The control section selects one program statement at a time from the program storage area,
interprets the statement, and sends the appropriate electronic impulses to the arithmetic-logic and storage
sections so they can carry out the instructions. The control section does not perform actual processing
operations on the data. The control section instructs the input device on when to startand stop transferring
data to the input storage area. It also tells the output device when to start and stop receiving data from the
output storage area.
ARITHMETIC-LOGIC SECTION.—
The arithmetic-logic section performs arithmetic operations, such as addition, subtraction,
multiplication, and division. Through internal logic capability, it tests various conditions encountered duringprocessing and takes action based on the result. At no time does processing take place in the storage section.
Data maybe transferred back and forth between these two sections several times before processing is
completed.

Computer architecture topics
Sub-definitions
Some practitioners of computer architecture at companies such as Intel and AMD use more fine distinctions:


Macroarchitecture -architectural layers that are more abstract than microarchitecture, e.g. ISA

Einstein College of Engineering




ISA (Instruction Set Architecture) - as defined above
Assembly ISA - a smart assembler may convert an abstract assembly language common to a group of
machines into slightly different machine language for different implementations
Programmer Visible Macroarchitecture -higher level language tools such as compilers may define a
consistent interface or contract to programmers using them, abstracting differences between
underlying ISA, UISA, and micro architectures. E.g. the C, C++, or Java standards define different
Programmer Visible Macro architecture - although in practice the C micro architecture for a particular
computer includes



UISA (Microcode...