My Nand to Tetris Journey

2025-05-09T00:00:00+00:00

Introduction</h2>
In March 2025, I signed up for the Coursera course From Nand to Tetris: Building a Modern Computer</a> by Shimon Schocken and Noam Nisan. I thought “Why not learn how computers work from the basics?” Spoiler:- It’s not as easy as it sounds. The course promised to turn me into a computer-building wizard, and I got pretty far completing four out of six projects.

Logic Gates from NAND</h2>
The course starts with a simple idea: using only the elementary NAND gate, you can construct all other logic gates necessary for a modern computer. This concept blew my mind, the idea that complex systems ultimately reduce to this simple building block.
I started by implementing basic logic gates in the NAND2Tetris Hardware Simulator</a> using hdl:
NOT gate</li> </ul>
CHIP Not { IN in; OUT out; PARTS: Nand (a = in, b = in, out = out); }</code></pre>

AND gate</li> </ul>
CHIP And { IN a, b; OUT out; PARTS: Nand (a = a, b = b, out = aNandb); Not (in = aNandb, out = out); }</code></pre>

OR gate</li> </ul>
CHIP Or { IN a, b; OUT out; PARTS: Not (in = a, out = nota); Not (in = b, out = notb); And (a = nota, b = notb, out = and); Not (in = and, out = out); }</code></pre> XOR gate</li> </ul> CHIP Xor { IN a, b; OUT out; PARTS: Not (in = a, out = nota); Not (in = b, out = notb); And (a = a, b = notb, out = temp1); And (a = nota, b = b, out = temp2); Or (a = temp1, b = temp2, out = out); }</code></pre> Pro Tip: Use NAND Game</a>! to understand how theses gates are formed using NAND. As It transforms theoretical concepts into visuals that make implementation much easier than it seems. From Gates to Chips</h2> Once I had a grip on basic gates, it was time to get serious and build some chips. Enter the realm of multiplexers and demultiplexers. These allow you to: MUX (Multiplexer): Choose which input signal to use.</li> DMUX (Demultiplexer): Route signals to different outputs based on selection bits.</li> </ul> I thought the difficulty would skyrocket when I started with the 16-bit and multi-way chips, but once I built the first 16-bit chip, the rest were a breeze, just a bit of grunt work, really. Arithmetic Components Next came the exciting part which is creating chips that can actually compute! I implemented: Half Adder (adding two bits)</li> Full Adder (adding three bits with carry)</li> Multi-bit Adder (for 16-bit )</li> The ALU (Arithmetic Logic Unit)</li> </ul> From Bits to Storage</h2> The next phase took me into the realm of computer memory, where I designed: Registers: Flip-flop based storage units that hold data temporarily</li> RAM8: A small 8-register memory unit</li> RAM64: A memory unit of 64-register</li> RAM512, RAM4K and RAM16K: Increasing memory units</li> Program Counter (PC)</li> </ul> This hierarchy of memory components taught me how computers are organized. Challenges and Limitations</h2> While I successfully completed four projects, the two modules focused on assembly language programming were… let’s just say, less successful. I realized I’m a visual learner who prefers tools like simulators. Still, the struggle was part of the fun. Sort of. Resources That Helped Me</h2> The NAND game (seriously, don’t skip it!)</li> Course forums where students swapped war stories about their challenges (misery loves company).</li> Drawing chips designs on paper before implementation</li> </ul> Conclusion</h2> While I didn’t complete all six projects, the four I finished gave me a solid foundation in computer architecture that I’ll build upon. If you’re curious about how computers really work from the ground up, I highly recommend this course. It’s tough, but incredibly rewarding. After all, who wouldn’t want to say, “I built a computer from scratch with just a NAND gate”?

Tech Cafe - Nand-to-Tetris

My Nand to Tetris Journey

Challenges and Limitations</h2>
While I successfully completed four projects, the two modules focused on assembly language programming were… let’s just say, less successful. I realized I’m a visual learner who prefers tools like simulators. Still, the struggle was part of the fun. Sort of.</p>