diff --git a/src/main.zig b/src/main.zig
index d86786c..f67623a 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -50,6 +50,7 @@ pub const Buffer = struct {
     output: *Wire,
 
     pub fn process(self: *Buffer) void {
+        self.output.digital = self.input.digital;
         self.output.analogSet(self.input.analog);
     }
 };
@@ -58,8 +59,26 @@ pub const Not = struct {
     input: *Wire,
     output: *Wire,
 
-    // TODO check implementation
-    pub fn process(self: *Buffer) void {
-        self.output.analogSet(1.0 - self.input.analog);
+    pub fn process(self: *Not) void {
+        self.output.digital = !self.input.digital;
+        self.output.analogSet(1.0 - self.input.analog); // TODO check implementation
+    }
+};
+
+pub const And = struct {
+    inputs: []Wire,
+    output: *Wire,
+
+    // TODO check implementation
+    pub fn process(self: *And) void {
+        var digital = self.inputs[0].digital;
+        if (digital) for (1..self.inputs.len - 1) |i| if (!self.inputs[i].digital) {
+            digital = false;
+            break;
+        };
+
+        // TODO analog
+
+        self.output.digital = digital;
     }
 };