completed RAM64

project03/a/RAM64.hdl

@@ -1,12 +1,12 @@
-// This file is part of the materials accompanying the book 
-// "The Elements of Computing Systems" by Nisan and Schocken, 
+// This file is part of the materials accompanying the book
+// "The Elements of Computing Systems" by Nisan and Schocken,
 // MIT Press. Book site: www.idc.ac.il/tecs
 // File name: projects/03/a/RAM64.hdl
 
 /**
  * Memory of 64 registers, each 16 bit-wide. Out hold the value
- * stored at the memory location specified by address. If load=1, then 
- * the in value is loaded into the memory location specified by address 
+ * stored at the memory location specified by address. If load=1, then
+ * the in value is loaded into the memory location specified by address
  * (the loaded value will be emitted to out after the next time step.)
  */
 
@@ -16,4 +16,23 @@ CHIP RAM64 {
 
     PARTS:
     // Put your code here.
+
+    // Address is 6 bits: xxxyyy
+    // The xxx refers to the particular RAM8 chip
+    // The yyy refers to the address on that chip
+
+    // Select the appropriate RAM8 chip with xxx
+    DMux8Way(in=load, sel=address[0..2], a=loadA, b=loadB, c=loadC, d=loadD, e=loadE, f=loadF, g=loadG, h=loadH);
+
+    // Feed yyy to all of them, and correct chip will get the load bit
+    RAM8(in=in, load=loadA, address=address[3..5], out=outA);
+    RAM8(in=in, load=loadB, address=address[3..5], out=outB);
+    RAM8(in=in, load=loadC, address=address[3..5], out=outC);
+    RAM8(in=in, load=loadD, address=address[3..5], out=outD);
+    RAM8(in=in, load=loadE, address=address[3..5], out=outE);
+    RAM8(in=in, load=loadF, address=address[3..5], out=outF);
+    RAM8(in=in, load=loadG, address=address[3..5], out=outG);
+    RAM8(in=in, load=loadH, address=address[3..5], out=outH);
+
+    Mux8Way16(a=outA, b=outB, c=outC, d=outD, e=outE, f=outF, g=outG, h=outH, sel=address[0..2], out=out);
 }