Update README.md

Author: nicolasloizeau

README.md

@@ -10,4 +10,113 @@ programing instructions are in assembly.py
 ## Video
 <a href="https://www.youtube.com/watch?v=WfuhbI8HE7s" target="_blank">![](./images/video.png)</a>
 
+## Usage
+Open <a href="http://golly.sourceforge.net/">Golly</a>: "Files>Run script.." select assembly.py.
+## Programming instructions
+The pattern can be programmed to run your own algorithm by modifying the program variable in assembly.py
 
+Variable names start by "a" followed by a number. eg a1 a2 a3 a10 are good variable names
+a0 is used for storing the current program line, so be carefull, modifiying a0 will jump to the line a0
+the instructions are:
+```
+(let be n an integer in base 10)
+write a1 n
+-> write n to the variable a1 (written in 2's complement if signed)
+
+goto n
+-> go to the line n (first line is line 0)
+
+move a1 a2
+-> a1=a2
+
+jump a1
+-> jump the a1 next lines
+
+print a1
+-> print a1
+
+disp a1 a2
+-> draw a pixel of coordinates a1 a2
+
+erase
+-> erase the 2d display
+
+rfb a1 a2
+-> a1 = memory[a2] ; write the content of the address stored in a2 to a1; (if a2=N, a1=aN)
+
+wfb a1 a2
+-> memory[a2] = a1 ; write a1 to the address stored in a2; (if a2=N, aN=a1)
+
+++ a1 a2
+-> a1=a2+1
+
+- a1 a2 a3
+-> a1 = a2-a3
+
++ a1 a2 a3
+-> a1 = a2+a3
+
+or a1 a2 a3
+-> a1=bitwiseOR(a2,a3)
+
+and a1 a2 a3
+-> a1=bitwiseAND(a2,a3)
+
+xor a1 a2 a3
+-> a1=bitwiseXOR(a2,a3)
+
+not a1 a2
+-> a1=bitwiseNOT(a2)
+
+>> a1 a2
+-> a1 = shift_right(a2)
+
+<< a1 a2
+-> a1 = shift_left(a2)
+
+rr a1 a2
+-> a1 = rotate_right(a2)
+
+rl a1 a2
+-> a1 = rotate_left(a2)
+
+=0 a1 a2
+-> a1 = 1 if a2==0 else a1=0
+
+!=0 a1 a2
+-> a1 = 1 if a2!=0 else a1=0
+
+less a1 a2
+-> a1 = 1 if less_significant_bit(a2)==1 else a1=0
+
+most a1 a2
+-> a1 = 1 if most_significant_bit(a2)==1 else a1=0
+
+*- a1 a2
+-> a1 = -a2
+```
+
+The wollowing example will print Fibonacci sequence:
+```
+
+program = """
+write a1 1
+write a2 1
++ a1 a1 a2
+print a1
++ a2 a1 a2
+print a2
+goto 2
+"""
+```
+
+
+## Screenshots
+
+![](./images/computer.png)
+![](./images/alu.png)
+![](./images/adder.png)
+![](./images/decoder.png)
+![](./images/display.png)
+![](./images/memory.png)
+![](./images/output.png)