NandGame.com Solutions

1.1 - Invert - Getting the basic tools

1.2 - And

1.3 - Or

1.4 - XOR - I originally built this with an OR, NAND and ANDgate. I decided during a later level that I would use NAND wherever it wasn't impractical, so I came back to this one. Breaking it down to NANDs lets it use fewer gates.

2.1 - Half Adder - And tossing out those tools. I built this originally with an OR gate and an Inverter. In later levels, you need to expand your tools to optimize the NAND gates properly, so I went back and expanded as many as I could.

2.2 - Full Adder - Similar to the above, but you need to add the carry bit as well.

2.3 - Multi-bit Adder - I haven't expanded and optimized this one yet, but it's gonna be messy when I do.

2.4 - Increment - Carry successfully ignored.

2.5 - Subtraction - Fun fact, when making a binary number a negative, you'll have to add 1 to get the actual number.

2.6 - Equal to Zero - Just expanded, using 3 ORs and an Inverter is already optimal.

3.1 - Selector - Continuing to use only NAND gates.

3.2 - Switch - I should probably set those two top NANDs to be back to inverters. It cleans it up a little bit, and an INV and NAND are the exact same thing.

4.1 - Latch - Simplest basic toggle.

4.2 - Data Flip Flop

4.3 - Register - I really can't see where I can trim this down. I have no spare singles, and by expanding it to just NANDs I was able to use have the two DFFs share the ST and CL inputs.

4.4 - Counter - Getting to the point where expanding is so impractical due to limited space for placing the NANDs

4.5 - RAM - I'm not sure I could place 293 NANDS on the screen and still see where the connections go.

5.1 - Unary ALU - Simple, but not optimal. I expect that if I expand the selects into NANDs, like I plan to later, I'll be able to strip out a few gates and optimize this thing.

5.2 - ALU - Not sure yet how I can strip out some components. Need to go back and optimize this later.

5.3 - Condition - Fewer components, such as putting in the ORs and Inverters here, but I like the way it looks, and would prefer to use NANDs where I can.

6.1 - Combined Memory - Optimizing my Register and RAM should optimize this further than merely the simplest solution.

6.2 - Instruction Decoder - I want to build a switch 16, but the custom components feature isn't working for me, and without a combiner or read16 I'm not sure I can do it.

6.3 - Control Unit - Uggh. It's so ugly.

6.4 - Program Engine - Clearly the most difficult one yet.

6.5 - Computer - Not much to say about this one. One more to go.

6.6 - Input and Output - Sure, technically I can replace the inverted NAND with an AND to make it 3, which counts as simplest. But why break tradition of expanding out my tools when I can?

Nandgame.com
Good game, gave me a new appreciation and understanding of electronic circuitry.