Nand2tetris is a course where we build a full general purpose computer up from basic logic gates - in fact, just NAND gates. This is because a NAND gate can be used to form all the other basic logic gates - AND, OR and NOT. The “hardware” will be built in a simplified Hardware Description Language (or HDL). This HDL is similar to the “actual” HDLs like Verilog and VHDL. The course also introduces a “testing” language which provides a way to define a bunch of test cases with inputs and outputs for a given “chip” spec. The supplied “Hardware Simulation” program is able to load HDL files as well as testing scripts and verify designs.
The goal is to build up the next building blocks - CPU, RAM and “chipset” from the basic logic gates, and tehn build it into a computer platform with its own assembly language. Later the second part of the course involves building a language called “Hack” which can presumably be used to build Tetris.