can do without DMux4Way and Mux4Way16

projects/05/Memory.hdl

@@ -35,19 +35,15 @@ CHIP Memory {
     // 10 11111 1111 1111 <- Last  SCREEN   Register
     // 11 00000 0000 0000 <- One   Keyboard Register
 
-    DMux4Way(in=load, sel=address[13..14], a=toRAM1,
-                                           b=toRAM2,
-                                           c=toScreen,
-                                           d=notNeeded);
+    // Keyboard doesn't require load bit
+    DMux(in=load, sel=address[14], a=toRAM, b=toSCR);
 
-    Or(a=toRAM1, b=toRAM2, out=toRAM);
+    // 14 bit address for RAM (16384 registers)
+    // 13 bit address for SCR (8192  registers)
     RAM16K(in=in, load=toRAM, address=address[0..13], out=fromRAM);
-    Screen(in=in, load=toScreen, address=address[0..12], out=fromScreen);
-    Keyboard(out=fromKeyboard);
-
-    Mux4Way16(sel=address[13..14], out=out, a=fromRAM,
-                                            b=fromRAM,
-                                            c=fromScreen,
-                                            d=fromKeyboard);
+    Screen(in=in, load=toSCR, address=address[0..12], out=fromSCR);
+    Keyboard(out=fromKBD);
 
+    Mux16(a=fromSCR, b=fromKBD, sel=address[13], out=fromDEV);
+    Mux16(a=fromRAM, b=fromDEV, sel=address[14], out=out);
 }