MIT 6.004 Computation Structures and digiwleea: two paths from gates to a CPU
Computation Structures is MIT's introductory course on the design of digital systems (6.004), and its materials are free online at computationstructures.org: lectures with notes, short videos with transcripts, worksheets drawn from old quizzes, textbook-style notes and labs. Its summary says it starts at the device level and builds up a hierarchy of logic gates, combinational and sequential circuits, finite-state machines, processors and complete systems, and that students complete the gate-level design of a RISC processor, the Beta, in the labs. The 11 labs, by Chris Terman, run in the browser with the course's own tools: the Jade circuit simulator, the BSim Beta simulator and TMSim for Turing machines, from CMOS Technology and a CMOS adder through FSMs, a 32-bit ALU and assembly language to building the Beta, caches and a tiny operating system. 6.004 is a university course with lectures and labs; digiwleea is a hands-on browser course with a checked step for every part. They cover much of the same ground.
What 6.004 is good at
Depth and rigour: real CMOS electrical analysis (the first lab measures an inverter's voltage transfer curve and noise margins in Jade), a full 32-bit ALU, a RISC processor with caches, and the software side up to procedures, stacks and an operating system. If you want the MIT course itself, with lectures and problem sets, it is excellent and free. Its site notes the materials are a work in progress. (digiwleea is an independent project, not affiliated with MIT.)
How digiwleea is different
digiwleea is smaller in scope and more guided. It simulates logic at the switch level (every wire is 0, 1 or floating) rather than voltages, so you build NOT and NAND from NMOS and PMOS transistors without electrical analysis, then adders, latches, registers, RAM and an 8-bit accumulator CPU whose capstone runs a stored program, through a 40+ level course where every part is checked against its truth table, with hints and an AI tutor (Wleea). Each finished part is saved and reused in the next level, so the CPU is literally built from your own gates. A good combination is digiwleea for building intuition part by part, then 6.004 for the full processor and the theory; our computer architecture course comparison covers other courses too.
| MIT 6.004 Computation Structures | digiwleea | |
|---|---|---|
| Format | University course: lectures, videos, worksheets, labs | Guided interactive course plus a free lab |
| Circuit level | CMOS with voltages (Jade), then gates | Switch-level transistors (0, 1, floating), then gates |
| The processor | The Beta, a 32-bit RISC processor | A small 8-bit accumulator CPU |
| Tools | Jade, BSim and TMSim in the browser | One lab and simulator in the browser |
| Price | Free online materials | Free lab and Act I; Premium for the full course |
No sign-up is needed to start: open the lab and place your first transistor, or read the free theory course. The account (and the AI tutor) are optional.
More comparisons: Books, courses and projects
See for yourself: build a logic gate from transistors in the simulator, then follow the path from sand to an 8-bit CPU.
Open the digiwleea lab →Frequently asked
What is MIT 6.004?
6.004 Computation Structures is MIT's introductory course on digital systems design. It builds from the device level through gates, combinational and sequential circuits and finite-state machines to processors, and its labs have students design a RISC processor called the Beta.
Are the 6.004 materials free?
Yes. Lectures, videos, worksheets, notes and labs are online at computationstructures.org, with browser-based tools such as the Jade circuit simulator and the BSim Beta simulator.
What is BSim?
In 6.004, BSim is the Beta simulator: a browser tool for running assembly programs on the course's Beta processor. Jade is the course's circuit simulator.