Like the Little Man Computer, but you build the CPU yourself
The Little Man Computer (LMC) is an instructional model of a computer created by Dr. Stuart Madnick in 1965. It has 100 memory locations, an accumulator, a program counter, and an input and an output area, and it runs a small decimal instruction set: ADD, SUB, STA, LDA, BRA, BRZ, BRP, INP, OUT and HLT. You usually run it in a free browser simulator such as Peter Higginson's, where you write a program, assemble it and run or step through it. If that is what brought you here, digiwleea is a free, in-browser alternative with a different angle: you build a computer from the transistor up.
What Little Man Computer is good at
The LMC is a great first look at how a processor runs a program. The numbers are decimal and every instruction is three digits, so you can follow the fetch and execute steps by eye, see that instructions and data share the same memory, and write real programs with loops and branches. (digiwleea is an independent project, not affiliated with any LMC simulator.)
How digiwleea is different
digiwleea answers the next question: what is inside the box? You build the processor itself, in binary, from CMOS transistors up: gates, adders, an ALU, registers, RAM, a program counter and the control logic, following a guided 40+ level course with an AI tutor (Wleea). Then you program it in an assembly language that will feel familiar, with LOAD, ADD, SUB, STORE, JMP, JZ, OUT and HALT, and watch each instruction move through the circuit you wired. The CPU simulator and the assembly lessons are free to try. Pick the LMC to practise assembly and the fetch-execute cycle in minutes; pick digiwleea to build the machine that runs it.
| Little Man Computer | digiwleea | |
|---|---|---|
| What it is | A model CPU you program | A CPU you build, then program |
| Number system | Decimal (3-digit instructions) | Binary (8-bit instructions) |
| Memory | 100 locations (0 to 99) | 16 addresses (4-bit operand) |
| Instructions | ADD, SUB, STA, LDA, BRA, BRZ, BRP, INP, OUT, HLT | LOAD, ADD, SUB, STORE, JMP, JZ, OUT, HALT |
| Inside the CPU | Abstract (the little man) | Every gate, from transistors up |
| Price | Free simulators | 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.
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
Is digiwleea a good Little Man Computer alternative?
Yes, if you want to understand digital logic from the ground up. digiwleea is a free, in-browser simulator with a guided 40+ level course where you build every gate from CMOS transistors and work up to a real 8-bit CPU, with an AI tutor to help.
Is digiwleea free?
The sandbox lab and the first act of the course are free and need no sign-up. An optional account adds the AI tutor and cross-device sync; the full course and expanded AI tutoring are included in the monthly or annual Premium subscription.
Do I need to install anything?
No. digiwleea runs entirely in your browser, on desktop or mobile, and works offline once loaded.