1. CS3369: Real Time Computer Control Software
Who I am:
Dr. Lusheng WANG
Dept. of Computer Science
office: Y6429
phone:
web site:
9/21/2018
CS3369 Real Time Control Software/WANG Lusheng

2. Suggested References:
D.M. Auslander and C.H. Tham, “Real-time software for control: Programming examples in C”, Prentice Hall, USA, 1990.
S. Bennett, “Real-time computer control: An introduction”, Prentice Hall, UK, 1988.
Babu Joseph, Real-time personal computing (for data acquisition and control), Prentice Hall, Englewood Cliffs, New Jersey, 1989.
P. Norton, P. Aitken, R. Wilton, “PC Programmer’s Bible”, 1993.
Turbo C, User Guide, ver. 2.0 Borland International, 1988
Dr. James T. Smith, “Advance Turbo C”, McGraw-Hill Book Company, 1989.
H.M. Deitel and P. J. Deitel, “C++ How to program”, Prentice Hall, 1998.
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CS3369 Real Time Control Software/WANG Lusheng

3. Four Parts of the Course:
Introduction to real time systems and basic computer organization
Real time scheduling
Real time system development methodology
Real time programming
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CS3369 Real Time Control Software/WANG Lusheng

4. CS3369 Real Time Control Software/WANG Lusheng
What I Cover:
some basic concepts in real time embedded systems
computers organization
programming in C++
interrupts and controls
top down design
requirements specification
program testing
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CS3369 Real Time Control Software/WANG Lusheng

5. Evaluation of the Course
Course work: 40%
Two Assignments. 20% each.
I give you time in the labs to do the two assignments.
Project: optional. 10% bonus for the course work.
A final exam: 60%;
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CS3369 Real Time Control Software/WANG Lusheng

6. CS3369 Real Time Control Software/WANG Lusheng
How to Teach
Contents are divided into four classes
1. Basic part -- every body must understand in order to pass
2. Moderate part -- most of students should understand.
Aim at B or above.
3. Hard part -- used to distinguish students.
Aim at A or above.
4. Fun part -- just illustrate that some interesting things
can be done if one works very hard.
-- useful knowledge that will not be tested.
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CS3369 Real Time Control Software/WANG Lusheng

7. CS3369 Real Time Control Software/WANG Lusheng
How to Learn
1. Attend every lecture and tutorial. (4 hours per week)
2. Try to go with me when I am talking
3. Ask questions immediately
4. Try to fix all problems during the 2 hours tutorial
5. Ask other students to help during the lab.
Every student should be able to finish basic part in tutorial/lab.
Most of students should be able to finish the moderate part
in tutorial/lab.
If you do the above, you should be able to get at least B+.
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CS3369 Real Time Control Software/WANG Lusheng

8. CS3369 Real Time Control Software/WANG Lusheng
Real Time Embedded Systems
Computer systems that operate as an integral part of physical systems, and very often, react and readjust control variables quickly to the changes in physical systems.
Functionality:
monitor equipment performance
timely control equipment operations
provide human-machine interfaces
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CS3369 Real Time Control Software/WANG Lusheng

9. CS3369 Real Time Control Software/WANG Lusheng
Three types of Real Time Embedded Systems
Hard: Each job enters the system with a deadline before which it has to be served. Later response is not allowed.
Soft: The average response time for the jobs is to be minimized.
Firm: A combination of soft and hard real time requirements.
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CS3369 Real Time Control Software/WANG Lusheng

10. CS3369 Real Time Control Software/WANG Lusheng
Examples of Real Time Embedded Systems:
Air-conditioning Control
Elevator Control
Traffic Light Control
Video Games
TV Remote Control
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CS3369 Real Time Control Software/WANG Lusheng

11. Introduction to Computer Hardware
We will learn the following:
1. Architecture of computer hardware
2. Execution of an instruction
3. Execution of a program
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CS3369 Real Time Control Software/WANG Lusheng

12. Basic hardware components
Central Processing Unit
Memory
Input/Output Sub-systems
Buses
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CS3369 Real Time Control Software/WANG Lusheng

13. Architecture of Computer Hardware
cpu
Peripherals
General
Purpose
Registers
Arithmetic and
Logic Unit
Control
Unit
Main
Memory
Input/Output
Interfaces
data/address/control buses
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CS3369 Real Time Control Software/WANG Lusheng

14. CS3369 Real Time Control Software/WANG Lusheng
What Does a Computer Do?
Do some computation according to users’ willing
1. Users tell computers what to do via programs.
2. A program is a sequence of instructions.
3. Instructions are the basic operations computers can do.
4. Examples of Instruction
add 2, sub 4, 2
(compute 2 + 3) (compute 4 - 2)
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CS3369 Real Time Control Software/WANG Lusheng

15. CS3369 Real Time Control Software/WANG Lusheng
An Example of a Program
The instructions are executed sequentially
There are some instructions allow jump
x=3*5+6-7; (High level language)
x=3; (Low level language)
x=x*5; (A set of instructions)
x=x+6;
x=x-7;
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CS3369 Real Time Control Software/WANG Lusheng

16. Central Processing Unit (CPU)
Execute program stored in the main memory by fetching their instructions, examining them and then executing them one after another
Components of CPU
1.Arithmetic logical unit (ALU) – performs operations such as addition and boolean AND needed to carry out the instructions
2.Registers – high-speed memory used to store temporary results and certain control information used by the CPU. CPU registers such as program counter (PC), instruction registers (IR), status registers
3.Control unit (CU) – fetching instructions from main memory and determining their type
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CS3369 Real Time Control Software/WANG Lusheng

17. CS3369 Real Time Control Software/WANG Lusheng
Memory
part of the computer where program and data are stored and to be processed by the processor
Also called Main Memory, Random Access Memory (RAM)
Bits - the basic unit of memory is the binary digit, a bit contains a "0" or "1".
Memory contains many bits organised in linear order.
Several bits form a “cell” containing a piece of information (data, instruction, integer, character, etc)
The size of the cell can be a byte or several successive bytes.
Each cell has a reference number, called its address, by which program can refer to.
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CS3369 Real Time Control Software/WANG Lusheng

18. CS3369 Real Time Control Software/WANG Lusheng
Buses
Communication links allowing data, instructions and memory addresses to be referred between different components (CPU, main memory and I/O devices) in a computer system.
Example:
UNIBUS - Digital Computer Inc.,
PC Bus - Industrial Standard PC bus
Peripheral Component Interconnect (PCI) Bus
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CS3369 Real Time Control Software/WANG Lusheng

19. CS3369 Real Time Control Software/WANG Lusheng
Input/Output Device
Input Devices
Allows computer user to issue commands, asks for information, adds new data and programs to the computer.
The computer receives input from the press of a key or button, touch of a finger on a screen, optical scanners, spoken words and many sources.
Output devices
Display results to the user. Includes video display screen, printers, audio speakers.
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CS3369 Real Time Control Software/WANG Lusheng

20. CS3369 Real Time Control Software/WANG Lusheng
General
Purpose
Registers
Arithmetic and
Logic Unit
Control
Unit
data/address/control buses
Main
Memory
Input/Output
Interfaces
real-time clock
digital signals
pulse operations
analog-to-digital
conversion
digital-to- analog
disk drive
CD Drive
printer
Key board
…...
Display
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CS3369 Real Time Control Software/WANG Lusheng

21. Execution of an Instruction
Fetch the instruction from the memory
Execution of
an instruction
is achieved by
a sequence of
commands
issues by the
control unit.
Fetch the operands from the memory
Perform the operation
Update the program counter no
Check interrupt
yes
Interrupt processing
Next Instruction
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CS3369 Real Time Control Software/WANG Lusheng

22. CS3369 Real Time Control Software/WANG Lusheng
Execution of a Program
Fetch the instruction from the memory
Fetch the operands from the memory
Perform the operation
LOAD b, R1
Update the program counter
A program is
a sequence of
instructions. no
Check interrupt
yes
Fetch the instruction from the memory
Fetch the operands from the memory
Perform the operation
ADD R1, 1
Update the program counter
a = b + 1; no
Check interrupt
yes
Fetch the instruction from the memory
Fetch the operands from the memory
Perform the operation
STORE R1, a
Update the program counter no
Check interrupt
yes
…...
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CS3369 Real Time Control Software/WANG Lusheng

23. CS3369 Real Time Control Software/WANG Lusheng
Computer Languages
Users use languages to write instructions and programs.
There are lots of computer languages that can be classified
into two categories -- low level and high level languages
Low Level Languages:
Machine language -binary code
Assembly language
Examples of Low Level Languages:
ADD A3, D Assembly instruction
Machine language
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CS3369 Real Time Control Software/WANG Lusheng

24. High Level Computer Languages
English-like languages -- easy to handle for users
-- computers cannot directly understand
Examples: C, C++, PASCAL, LISP, COBAL, etc
Running a program written in high level languages:
1. Compile the program
(translate the high level language into a machine
language. Done automatically by a software called
compiler.)
2. Execute the translated code. (executable code)
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CS3369 Real Time Control Software/WANG Lusheng

25. CS3369 Real Time Control Software/WANG Lusheng
The First C Program
#include<stdio.h>
int main(void) {
printf(“Hello, world! \n”);
return 0; }
Output:
Hello, world! \n stand for “new line”
It will not be shown on the screen
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CS3369 Real Time Control Software/WANG Lusheng

26. CS3369 Real Time Control Software/WANG Lusheng
The First C++ Program
#include<iostream.h> /* to include the file iostream.h */
int main(void) /* part of every C++ program */
{ /* { The beginning of main function */
cout <<“Hello, world! \n”; /*print out Hello, world! On screen */
return 0; /* exit a function */
} /*} The end of main function */
Output:
Hello, world! \n stand for “new line”
It will not be shown on the screen
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CS3369 Real Time Control Software/WANG Lusheng

27. The first program for computation
#include <iostream.h> Note that, there are three variables
x, y, and z. All are of type integer.
int main(void) Each integer variable can store
{ an integer. The variable itself has
int x,y;z; an address, which is automatically
assigned by the system (computer).
x = 1;
y = 2;
z = x+ y;
cout <<“The sum of x and y is” << z;
return 0; }
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CS3369 Real Time Control Software/WANG Lusheng

28. The address of a variable
In C, the address of a variable can be known by user.
#include <iostream.h>
int main (void) {
int x;
cout <<“The address of x is” << &x;
return 0; }
Output:
Note that, each execution gives a different address.
Exercise: Try to run the program three times. What happens?
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CS3369 Real Time Control Software/WANG Lusheng

29. Examples of C++ Programs We Intend to Deal with
Print out a person that can move
Some program about graphics (G1 and G2)
Time Delay-- create movies (G3, also person)
Move keys with interrupts (key)
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CS3369 Real Time Control Software/WANG Lusheng

30. CS3369 Real Time Control Software/WANG Lusheng
Summary
1. Real time embedded systems.
2. Computer architecture
3. Memory
4. Execution of instructions and programs.
5. C++
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CS3369 Real Time Control Software/WANG Lusheng