M projects/05/Memory.hdl → projects/05/Memory.hdl

@@ -27,5 +27,25 @@ IN in[16], load, address[15];
     OUT out[16];
 
     PARTS:
-    // Put your code here:
-}+    // Note: I just realized that pin names can be mixed-case, so I've changed
+    // my pin naming convention (I'd _still_ prefer to use underscores if they
+    // were allowed...)
+
+    // chooses whether value of load goes to RAM16 or memory-mapped screen
+    DMux(in=load, sel=address[14], a=loadToRAM, b=loadToScreen);
+
+    RAM16K(in=in, address=address[0..13], load=loadToRAM, out=ramOut);
+    Screen(in=in, address=address[0..12], load=loadToScreen, out=screenOut);
+    Keyboard(out=keyboardOut);
+
+    // choose between screen and keyboard (selection determined by whether both
+    // address[13] and address[14] are set
+    // (An aside: this approach has the added benefit that accessing "invalid
+    // addresses", which are above 0x6000, simply results in accessing the
+    // keyboard. I feel clever)
+    And(a=address[13], b=address[14], out=screenOrKeyboard);
+    Mux16(a=screenOut, b=keyboardOut, sel=screenOrKeyboard, out=peripheralOut);
+
+    // choose between RAM and screen/keyboard (determined by address[14]);
+    Mux16(a=ramOut, b=peripheralOut, sel=address[14], out=out);
+}

A projects/05/PROGRESS.md

@@ -0,0 +1,10 @@ 
+
+# Progress
+
+## TODO
+Computer
+CPU
+
+## DONE
+Memory
+