VeryBasic 4-bit (RISC) Computer

It's a 4-bit programable micro-controller,That has only LOAD,MOV,SUB,ADD,JNZ,JMP and RESET features due
it's limit of 4-bit instruciton set. It uses 8-bit address bus for addressing upto 255-addresses
meaning upto 255 instructions can be loaded.
It uses 4-bit in a clever way to make room for more instrucitons. Like first 10sets are used up by number
from 0-9 but we use number explictly only during load process so, we can check if we are currenlty
in load mode or not if not then treat those as instructions which allowed me to add more Instruction
set. After the addition of JNZ now we can do conditional programming , and the ADD & SUB feature allows
to have more controll over the A,B & C registers. It is a raw circuit and you can visualize it on Logisim-Evlution. Open up the last modified .circ file as I am adding new feature in new circuit every
day.

instructions:-

A -> load data to A
B -> load data to B
C -> load data to C
JNZ -> jump when C is not zero(conditional jump)
JMP -> jump to the nth line of code
SUB -> subtract from choosen register
ADD -> add to choosen register

Opcode values:-

IR       Value
0     -> 0b0        <br>
1     -> 0b1        <br>
2     -> 0b10       <br>
3     -> 0b11       <br>
4     -> 0b100      <br>
5     -> 0b101      <br>
6     -> 0b110      <br>
7     -> 0b111      <br>
8     -> 0b1000     <br>
9     -> 0b1001     <br>
A     -> 0b1010     <br>
B     -> 0b1011     <br>
C     -> 0b1100     <br>
SUM   -> 0b1000     <br>
SUB   -> 0b1001     <br>
JNZ   -> 0b1110     <br>
JMP   -> 0b1111     <br>
RESET -> 0b1101     <br>

Explanation of opcode

Every instructions has their own binary value. And due to lack of enough bits<br>
the numericals bits are reused for other instrucitons as the numericals are only<br>
used while on LOAD and JUMP process so on everyother situation the numbers bits will<br>
be used for other instructions set to make it more functional.

Examples

A 1                         || Set value of A to 1               <br>
label1:B 0                  || Set value of B to 0               <br>
    JMP label1              || Go  to line with label1           <br>
A 7                         || Set A with value 7                <br>
A B                         || Move content of B to A || `A <- B`<br>
A C                         || Move content of C to A            <br>
C A                         || move content of A to C || `C <- A`<br>
SUB C 1                     || subrtact one from C
ADD C 5                     || add 5 to C
ADD A 9                     || add 9 to A 

#### Conditional Looping example
A 9
C 9
loop SUB C 1
     SUB A 1
     JNZ loop

This loop will continue until C is zero

Use '#' to comment out the line comment

Look at files Code Example for any refrence

1)It's displays 123456000456000456.... in 7-segment
2)It moves three stips of light/led from left to right and loops back infintely in main output led

To implement

Insted of realing on `C` to be zero add a FLAG register with these values:-
Z -> if last operation yeild zero or not
C -> if last operation yeild carry or not
And new Instructions like
JNC/JC one of it