This document discusses CPU, software, and operating systems. It defines software as programs that run on computers and categorizes them into system software like operating systems, and application software. It describes operating systems as system software that manages computer hardware and software resources, providing common services. It outlines the requirements of operating systems, including shielding hardware details from applications, substituting abstract services for physical hardware services, and optimizing resource allocation.

1. CPU and Software
Yong Heui Cho @ Mokwon University
Some of slides are referred to:
[1] Software, slideshare.

2. Basic Computer Design
9. AVR CPU – ATmega328
10. Role of CPU
11. CPU and Software
12. Analog and Digital I/O

3. 3
Machine vs. Software
3
• When a computer is using a particular program,
it is said to be running or executing that program.
• Two major categories of software
– System software, i.e., Operating System (OS)
– Application software
□ Courtesy to Software, slideshare.

4. 4
Types of SW
4□ Courtesy to Software, slideshare.

5. 5
Concept of OS
• Operating System
– System SW that manages computer HW and SW
resources and provides common services for computer
programs

6. 6
Why OS?
• Requirements of OS
– OS must shield the details of the HW from the application
programs, and thus from the user.
– OS has to substitute a set of abstract services to the application
programs, to replace the physical HW services. When applications
use these abstract services, the operations must be translated into
real HW operations.
– OS must act as a resource manager, optimizing the use of the
resources, and protecting them against misuse and abuse. When a
system provides multiuser or multitasking capabilities, resources
must be allocated fairly and equitably amongst a number of
competing requests.

7. 7
Concept of Kernel
• A main part of OS that manages input/output requests
from software and translates them into data processing
instructions for the CPU and other electronic components
of a computer

8. 8
Application SW
• Application software is a program that help people
accomplish specific tasks.
• Thousands of application are available; however
• some major categories that likely to be encounter
• are:
– Word processors
– Spreadsheets
– Database management software (DBMS)
– Multimedia, graphics and presentations
– Utilities
– Communications
8□ Courtesy to Software, slideshare.

9. Binary System
○ Binary System
– 0 or 1
– Notation: 10001001(2)
– Bit (binary digit)
– Byte = 8 bits
○ Decimal to Binary Conversion
9
652
32 … 1
16 … 0
08 … 0
04 … 0
02 … 0
01 … 0
2
2
2
2
2
1000001
128 64 32 16 8 4 2 1
0 1 0 0 0 0 0 1Binary :
□ Courtesy to 전재욱, 논리회로 설계실험, 성균관대학교.

10. Decimal & Hexadecimal
10□ Courtesy to Imran Waris, Digital and Logic Design, slideshare.

11. ASCII Code
• The American National Standard Institute (ANSI) solution
to represent the symbols with bits of data was the ASCII
character set.
• ASCII = American Standard Code for Information
Interchange
• Today ASCII is the most common character set
• used.
• ASCII was the seven bits code, now the eight bits code.
• The ISO (International Standard Organization) standard
expanded on the ASCII character set, to offer different sets
of characters for different language group.
11

12. ASCII Code Table
12

13. Unicode
• Unicode Worldwide Character Standard
represents each symbol by one - four bytes.
• With two bytes, a Unicode character can be any
one of more than 65,536 different characters or
symbols.
• Many software publishers, including Microsoft,
encourage their developers to use Unicode in
their programs.
13

14. Why Unicode?
14
unicode encoding layout