Update README.md

README.md

@@ -3,8 +3,71 @@ Square One is a virtual computer built from scratch, starting from the logic gat
 
 ## Architechture
 
-### Gates
+### Logic Gates (path: /gates)
-The gates are designed following a behavioural modelling philosophy (mostly for learning purposes, even though a data flow modelling system would be preferible for big projects)
+Logic gates are the lowest level point from which this project is implemented. They are written in Verilog and then simulated using iverilog on a dedicated testbench, and any FPGA simulator will actually work. See Resources for an online 16-bit FPGA simulator.
+Most of the gates also have a 16-bit version and eventually a n-way version (some even n-way-16-bit).
+
+Ex: a 4-way mux gate:
+'''
+'include "mux.v";
+'include "or4way.v";
+
+module mux4way(out, i0, i1, i2, i3, sel0, sel1);
+    input i0, i1, i2, i3;
+    input [3:0]sel;
+    output [3:0]out;
+    wire tmp0, tmp1, tmp2, tmp3;
+
+    wire [3:0] [1:0] sel0 = sel;
+    wire [0:3] [1:0] sel1 = sel;
+
+    not(notSel0, sel0);
+    not(notSel1, sel1);
+
+    and(tmp0, i0, notSel0);
+    and(tmp1, i1, sel0);
+    and(tmp2, i2, notSel1);
+    and(tmp3, i3, sel1);
+
+    or4way(out, tmp0, tmp1, tmp2, tmp3);
+
+endmodule
+'''
+
+#### Predefined gates (path: /gates/predefined)
+The predefined gates are by default implemented on Verilog/Systemverilog. Thus they are not strictly needed for building more advanced gates or chipset, but I still decided to add them as reference and learning purposes.
+
+#### Testbenches (path: /testbenches)
+Testbenches are a way to test the implementation of a particular gate using a Verilog compiler
+
+Ex: testbench for a xor gate:
+'''
+'include "gates/predefined/xor_gate.v"
+
+module xor_tb();
+    reg ta, tb;
+    wire ty;
+
+    xor_gate dut(y, ta, tb);
+
+    initial begin
+        ta=0, tb=0;
+        $monitor("IN: %b, %b ",ta, tb, "OUT: ",y);
+        ta=0, tb=1;
+        $monitor("IN: %b, %b ",ta, tb, "OUT: ",y);
+        ta=1, tb=0;
+        $monitor("IN: %b, %b ",ta, tb, "OUT: ",y);
+        ta=1, tb=1;
+    end
+endmodule
+'''
+
+### Arithmetic Logic Unit (path: /alu)
+The ALU is written is Systemverilog (such as the CPU and other complex components). It handles 16-bit values and performs numerous operations, as:
+
+
+
+## Usage
 
 ## Resources
 - Online Verilog Compiler:  https://www.tutorialspoint.com/compile_verilog_online.php