feat: memory hdl implementation

.gitignore

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+.DS_STORE

project-5-computer-architecture/hdl/Memory.hdl

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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: projects/5/Memory.hdl
+/**
+ * The complete address space of the Hack computer's memory,
+ * including RAM and memory-mapped I/O. 
+ * The chip facilitates read and write operations, as follows:
+ *     Read:  out(t) = Memory[address(t)](t)
+ *     Write: if load(t-1) then Memory[address(t-1)](t) = in(t-1)
+ * In words: the chip always outputs the value stored at the memory 
+ * location specified by address. If load=1, the in value is loaded 
+ * into the memory location specified by address. This value becomes 
+ * available through the out output from the next time step onward.
+ * Address space rules:
+ * Only the upper 16K+8K+1 words of the Memory chip are used. 
+ * Access to address>0x6000 is invalid and reads 0. Access to any address
+ * in the range 0x4000-0x5FFF results in accessing the screen memory 
+ * map. Access to address 0x6000 results in accessing the keyboard 
+ * memory map. The behavior in these addresses is described in the Screen
+ * and Keyboard chip specifications given in the lectures and the book.
+ */
+
+// * 4-way 16-bit multiplexor:
+// * out = a if sel = 00
+// *       b if sel = 01
+// *       c if sel = 10
+// *       d if sel = 11
+
+ // 0 - 16383 - Ram 16K
+ // 16384 - 24575 Screen 8K
+ // 24576 - 24576 Keyboard (1 word)
+ 
+ // 16383 = 0(01)1111111111111 Ram 16k
+ // 16384 = 0(10)0000000000000 Screen 8k
+ // 24576 = 0(11)0000000000000 Keyboard
+
+CHIP Memory {
+    IN in[16], load, address[15];
+    OUT out[16];
+
+    PARTS:
+    // Ram16K
+    Mux(a=load, b=false, sel=address[14], out=loadRam);
+    Mux(a=true, b=false, sel=address[14], out=isRam);
+    // Screen
+    Mux(a=false, b=load, sel=address[14], out=loadScreen);
+    Mux(a=false, b=true, sel=address[14], out=isScreen);
+    // Keyboard
+    Mux(a=false, b=true , sel=address[13], out=keyboard1);
+    Mux(a=false, b=true, sel=address[14], out=keyboard2);
+    // isKeyboard
+    And(a=keyboard1, b=keyboard2, out=isKeyboard);
+
+    // Logic
+	RAM16K(in=in, load=loadRam, address=address[0..13] , out=outRam);
+    Screen(in=in , load=loadScreen, address=address[0..12], out=outScreen);
+    Keyboard(out=keyboardOut);
+
+    // Output logic
+    Mux4Way16(a=outRam, b=outRam, c=outScreen, d=keyboardOut , sel=address[13..14] , out=out);
+}