The document provides an overview of computer organization and architecture, detailing the functions and design of digital systems' components, such as the CPU, memory, and control unit. It distinguishes between primary and secondary storage memory and explains both volatile and nonvolatile memory types. Additionally, it describes input and output units, emphasizing their roles in reading data and presenting processed results.

1. UNIT I
INTRODUCTION
Functional Units of Digital
System

2. Computer Organisation &
Architecture
A computer organization describes the functions and design
of the various units of digital computers.
Computer Architecture is defined as the functional operation of
the individual h/w unit in a computer system.
A computer architecture deals with the specification of an
instruction set and the hardware units that implement the
instructions.
A computer hardware consists of electronic circuits, displays,
magnetic and optic storage media and also the communication
facilities.

3. Functional units
Functional units is a part of a CPU that performs the
operations and calculations called for by the computer
program.
Computer consists of five main parts namely,
Input unit,
Central Processing Unit
•Memory unit
•Arithmetic & logical unit
•Control unit
Output unit

4. 1. Input Unit
Input units are used by a computer, which
read the data.

5. Few Parts of a Computer – An
Overview
COA PPT1 INTRODUCTION 5
Assemble the computer: https://www.youtube.com/watch?v=hWB2UHCT0dw

6. Fig: joysticks
Fig: Trackballs
Fig: Mouse Fig: Microphones

7. Memory unit
Memory unit is used to store programs and data.
Two types of memory exist. they are,
Primary storage, and
Secondary storage
Primary storage:
Primary memory contains a large number of semiconductor
storage cells, capable of storing a bit of information.
The bits of information are grouped into fixed size words.
The word length of a computer is between 16-64 bits.
Addresses are used to access the words from memory.

8. The memory is know as main memory in which program must resides.
Cache is also a kind of memory which is used to access the data very
soon. they are highly coupled with the processor.
Example: RAM,ROM.
Advantages:
Small, and
Fast
Disadvantages:
less storage capacity, and
costly

9. Secondary storage:
Secondary memory are used when large
amount of data and programs have to be stored.
Example:
Magnetic disks,
Magnetic tapes, and
Optical disks.
Fig: Magnetic disk
Fig: Magnetic tapes
Fig: Optical disk

10. • Volatile memory: when it loses power, it forgets. (retains data only if it is receiving power)
• Nonvolatile memory: A form of memory that retains data even in the absence of a power
source and that is used to store programs between runs.
• Main memory (primary memory): Memory used to hold programs while they are running
(DRAM)
– SRAM (Static RAM):Usage: Cache memory in CPUs, fast and expensive.
– DRAM (Dynamic RAM):Usage: Main system memory, requires periodic refreshing
– .
– Cache memory A small, fast memory that acts as a buffer for a slower, larger memory.
• Secondary memory: Nonvolatile memory used to store programs and data between runs
– Magnetic disk/Hard disk: form of nonvolatile secondary memory composed of rotating
platters coated with a magnetic recording material.
COA PPT1 INTRODUCTION 10

12. • What is a Electronic transistor?
• A transistor is a semiconductor device used to
amplify or switch electronic signals and
electrical power.
• It has three terminals: the emitter, base, and
collector for bipolar junction transistors (BJTs)
or source, gate, and drain for field-effect
transistors (FETs).

14. Output unit
Output units are used to send the processed results to the user.
Output devices display information in a way that you can
understand. The most common output device is a monitor.
Output devices are pieces of equipment that are used to get
information or any other response out from computer. These
devices display information that has been held or generated
within a computer.

15. Fig: Printer Fig: Graphics Displays Fig: CRT Displays
Some of the output units are,
Fig: Microfilm

16. Control unit
Control unit is used to coordinate the operations of the input,
output, memory, ALU in some way. It coordinates the operation
of all the units using control signals like timing signals.
Timing signals are the signals determining the time when a
given action must take place. A large set of control lines carriers
the signals used for timing and synchronization of events in all
units.