Hello ,

I am going to make decoder for micro controller , I want to know how does decoder make for microcontroller
so I made following example just for learning
I have 4 registers
I =Instruction Register
A= Address register
R1= register R1
R2 =register R2

I A R1 R2    out
0000  0000000000000001

0001  0000000000000010

0010  0000000000000100

0011  0000000000001000

0100  0000000000010000

0101  0000000000100000

0110  0000000001000000

0111  0000000010000000

1000  0000000100000000

1001  0000001000000000

1010  0000010000000000

1011  0000100000000000

1100  0001000000000000

1101  0010000000000000

1110  0100000000000000

1111  1000000000000000

Logic 0= deactivate

Logic 1= activate



Output = input

I A R1 R2 out

1 1 1 0 1 '' mov R1 '' // I,A R1, activate R2 deactivate

1 1 0 1 1 '' mov R2 '' // I,A R1, activate R2 deactivate


1 0 0 1 1 ?

1 1 0 1 1 ?


If I know Input then how to decide which function will decode ?

 

you have 4 bits used for input. you have 16 bits for output.
look up/google: 4-16 multiplexer