What is this
"Ershov Computer" is an interactive browser-based simulator of digital logic and computer architecture. Here you build a computer bottom-up: from the first wire and logic gates to an 8-bit processor with its own data bus, memory, and assembler — and in the finale you run Snake on it. In the advanced modules you move on to structural Verilog, the control unit, and exporting your design to a Tang Nano 9K board. Everything runs right in your browser — no installation, no sign-up.
What's inside
Let there be light!
Source → receiver. Your first wire.
Negation
NOT gate from a single NAND.
Perfect pair
AND gate from NAND and NOT.
At least one
OR gate via De Morgan's laws.
Strict choice
Exclusive OR (XOR).
Half Adder
Sum (XOR) + Carry (AND).
Full Adder
A, B, CarryIn → Sum, CarryOut.
8-bit Adder
Cascade of 8 adders. Buses.
Crossroads
MUX: digital 2-to-1 switch.
Loopback
SR latch from NOR. Foundation of memory.
Smart memory
D flip-flop. Captures on clock edge.
Tangible Memory
8-bit register from 8 DFFs. LEDs show the byte.
Operation Selection
Multiplexer picks the result: ADD, AND, or OR.
Heart of math
ALU: ADD, AND, OR, XOR, NOT, SHL, SHR.
System Pulse
Manual clock. The concept of Clock. Counter on LED8.
Program Counter
PC from register and ALU. Address sequencing.
Anatomy of a Decoder
Instruction → control signals.
FINALE: The Ershov Computer
Harvard processor. Build and program it!
Course Curriculum → — timeline of all 47 levels: task, difficulty, time, and outcome for each.
What you'll learn
Step-by-step learning
47 levels: a wire, AND, OR, NOT gates, adders, flip-flops, registers, an ALU, and a fully working 8-bit processor at the end. Each level unlocks new components.
Visual programming
At the start there is only an interactive canvas: connect logic elements with wires and watch the signals switch in real time. Circuit behavior is verified by interactive tests and truth tables right on the screen.
Real architecture
A full educational Harvard architecture: separate instruction memory (ROM) and data memory (RAM), an ALU with 8 operations, registers, and a program counter. You assemble the datapath yourself and see every tick of the processor.
Text-based design
After visual circuits, you'll master structural Verilog — a text language for hardware description. Gates, buses, and modules are described in code and appear instantly in the RTL Viewer.
How it works
Build circuits from logic gates in your browser. Drag components onto the canvas, connect them with wires, and see results instantly. The built-in checker compares your circuit against the truth table, so you immediately see which bits match and which don't.
Advanced Level
After the processor comes the best part: ROM and RAM modules, data buses, the instruction decoder, I/O ports. The built-in assembler lets you program the architecture you just built, and new components unlock peripherals and games.
Verilog Language
Moving from graphical elements to Verilog. A code editor with syntax highlighting and the built-in RTL Viewer turn your code into a visual circuit on the fly, help you build hierarchical modules, and debug the architecture at the level of buses and signals.
Computer Architecture
Design a control unit, connect switches and LEDs via Memory-Mapped I/O, and run the finished computer. The final project exports as a Verilog project for flashing onto a real FPGA board, the Tang Nano 9K: your processor running on real hardware.
AI Tutor
The AI tutor sits in the right sidebar. It analyzes your circuit, finds errors, and asks guiding questions so you can figure things out on your own. If you're truly stuck, it will show you a step-by-step solution.
Game Economy
Every completed level earns the in-game currency: transistors. Your engineer profile keeps the history of your wins, and a ready-made solution from a hint costs transistors. It's cheaper to figure it out yourself.
Knowledge Library
You don't need to search for answers elsewhere. The Library has everything you need:
- Level Guides — step-by-step walkthroughs for all 47 levels, including Verilog debugging
- Component Guides — datasheets for 43 elements with truth tables, pin descriptions, and usage examples
- Circuitry Articles — 58 articles on logic gates, processor architecture, assembly language, and more
- Interactive Demo Examples — live schematics of 9 gates: toggle inputs and watch the outputs change
Tools
Useful utilities for learning circuitry — all free, nothing to install:
- Logic Circuit Simulator — a free online simulator: 47 levels, ending with your own processor
- Truth Table Generator — a full table for any Boolean formula in seconds
- Number Base Converter — binary, decimal and hexadecimal, with two's complement
- Boolean Function Calculator — PDNF, PCNF, the Zhegalkin polynomial, Post classes, minimization and Karnaugh maps
- Verilog and FPGA — the "where to start" hub: article cycle, level 47 guide and the Ershov Board
- Comparison with other projects — NandGame, Turing Complete, Nand2Tetris
For Teachers
Ready-to-use materials for integrating the Ershov Computer course into your curriculum.
Methodology Guide
Detailed teaching guide: course philosophy, hardware platform, debugging, CPU evolution final project.
Project Pitch
A concise pitch for school administration: course value, educational outcomes, career guidance.
Ershov Board
Technical specification for the lab board: components, pin mapping, silkscreen, Ershov Loader.
Frequently Asked Questions
What is Ershov Computer?
An interactive browser-based simulator where you build an 8-bit processor step by step, from a NAND gate to assembly programming. No downloads required.
Is it free? What do I need to install?
Completely free, and it runs in your browser. Nothing to install, no sign-up: open the site and start.
Who is this for?
Students studying computer science, undergrads in technical fields, and anyone curious about how computers really work.
How is it different from NandGame?
In NandGame everything is built as an abstract math puzzle around a single NAND gate. "Ershov Computer" is closer to a hands-on digital logic course: we start with a visible wire and basic logic, take a close look at buses, memory addressing, Memory-Mapped I/O, and the instruction decoder, then move on to Verilog. Every level comes with a detailed guide, and components have datasheets.
Do I need to know programming?
No. The simulator is designed for complete beginners. You'll start with a simple wire and, by the end, write assembly programs for your own processor.
Who is this for
Students
Computer science in practice: circuits you assemble and test right away.
Undergraduates
A companion to a computer architecture course: gates, registers, ALU, and a full processor.
Enthusiasts
For everyone who wants to know why a processor runs exactly the code you write.
For schools and universities — how to bring «Ershov Computer» into your institution.
This is a CPU. Design your own!