From fcde733087959cf2c835144058911c093d22eaab Mon Sep 17 00:00:00 2001
From: Jonas <jonas@jjsoftware.dk>
Date: Fri, 6 Feb 2026 22:31:42 +0100
Subject: [PATCH] feat: memory hdl implementation

---
 .DS_Store                                     | Bin 8196 -> 8196 bytes
 .gitignore                                    |   1 +
 .../hdl/Memory.hdl                            |  62 ++++++++++++++++++
 3 files changed, 63 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 project-5-computer-architecture/hdl/Memory.hdl

diff --git a/.DS_Store b/.DS_Store
index 22e8635f8a045edabc92d6343ed9602be3bf43df..cf8da0e7675fc28d19cca8ef1c151e11e4253ce6 100644
GIT binary patch
delta 56
zcmZp1XmOa}&nUVvU^hRb=;ZSPMw{&fR<UxX6es5-<>%)xZY&gI+RQHT5JgCs2>=^o
B5|jV{

delta 168
zcmZp1XmOa}&nU4mU^hRb#N_h=Mw{&fR<SbWq)(n98X%IJ@8Xh_lb^)Ez`!x7z~GGe
ntmBT8mx($7B~q|Ta1>-11}Ep|7Hlk(WZcXy@sKJ;i7^5IywN!>

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..fd5106f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.DS_STORE
diff --git a/project-5-computer-architecture/hdl/Memory.hdl b/project-5-computer-architecture/hdl/Memory.hdl
new file mode 100644
index 0000000..2c6b2af
--- /dev/null
+++ b/project-5-computer-architecture/hdl/Memory.hdl
@@ -0,0 +1,62 @@
+// 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);
+}
\ No newline at end of file