project03: Compound RAM chips

03/b/RAM16K.hdl

@@ -13,5 +13,15 @@ CHIP RAM16K {
     OUT out[16];
 
     PARTS:
-    //// Replace this comment with your code.
+    // find which RAM4K to load by address (from high two bits)
+    DMux4Way(in=load, sel=address[12..13], a=load0, b=load1, c=load2, d=load3);
+
+    // 4 RAM4K chips (low 12 bits select register within each)
+    RAM4K(in=in, load=load0, address=address[0..11], out=out0);
+    RAM4K(in=in, load=load1, address=address[0..11], out=out1);
+    RAM4K(in=in, load=load2, address=address[0..11], out=out2);
+    RAM4K(in=in, load=load3, address=address[0..11], out=out3);
+
+    // select which RAM4K output to send
+    Mux4Way16(a=out0, b=out1, c=out2, d=out3, sel=address[12..13], out=out);
 }