Thyristor is, a three terminal, four layers solid state semiconductor device, each layer consisting of alternately N-type or P-type material, i.e; P-N-P-N.
The conventional thyristor is also known by the name SCR (Silicon Controlled Rectifier).
 They are operated as bistable switches, operating from non conducting state to conducting state.
Thyristors can be assumed as ideal switches for many application, but the practical thyristors exhibit certain characteristics and limitations. 
 

End as a subscript   
To access the last element of a matrix along a given dimension, use  
end as a subscript. This allows you to go to the final element without  
knowing in advance how big the matrix is. For example:  

>> q = 4:10    
q=   
4   5   6   7   8   9   10    

>> q(end)   
ans = 10  

The Colon Operator 
The colon" : " is one of MATLAB’s most important operators. It occurs 
in several different forms. The expression 
>>1:10 
is a row vector containing the integers from 1 to 10 
1 2 3 4 5 6 7 8 9 10 
To obtain nonunit spacing, specify an increment. For example, 
>>100:-7:50 
is 
100 93 86 79 72 65 58 51 
• End as a subscript 
To access the last element of a matrix along a given dimension, use end 

insert and delete rows and columns:

>> A 
A =

= [1 2 3 ; 4 5 6 ; 7 8 9]

1 2 3 
4 5 6 
7 8 9

>> A(2,2)

an

s

= 5

>> A(3,3)

an

s

= 9 

Lecture2: 
A first steps: 
To get matlab to work out 1 + 1, type the following at the prompt: 
1+1 
matlab responds with 
ans = 2 
The answer to the typed command is given the name ans. In fact ans is 
now a variable that you can use again. For example you can type 
ans*ans 
to check that 2 × 2=4: 
ans*ans 
ans = 4 
Matlab has updated the value of ans to be 4. 
The spacing of operators in formulas does not matter. The following 
formulas both give the same answer: 

1- Introduction:

MEMORY: 
It is a storage device. It stores program instructions, data and the results. 
There are two kind of memories; 
semiconductor memories & magnetic memories. (1): Semiconductor 
memories are faster, smaller, and lighter and consume less power. 
Semiconductor memories are used as the main memory of a computer. (2): 
Magnetic memories are slow but they are cheaper than semiconductor 
memories. Magnetic memories are used as the secondary memories of a 
computer for bulk storage of data and information’s. 

The Bussed Architecture for Microprocessor: 
The first question is what is a ‘Bus’? Bus is a group of parallel lines that 
connect two or more devices as shown in fig.2. It carries information in bits. 
Whenever processor (CPU) needs to access any memory or I/O device of 
the microcomputer system.

Central Processing Unit: 
The CPU consists of ALU (Arithmetic and Logic Unit), register unit and control 
unit. The CPU fetches the stored instructions from the program memory, data 
word from data memory or from an input device and after processing the data 
stores the result in data memory or sends it to an output device. 
a) ALU (Arithmetic and Logic Unit) 
This unit performs computing functions these functions are arithmetic operations 
such as addition, subtraction and logical operation such as AND, OR, XOR,