Frequently Asked Questions

DigiSim.io is a professional web-based platform for learning, designing, and simulating digital logic circuits. It provides an interactive environment with over 50 components, from basic logic gates to complex CPU architectures, designed for students, educators, and professionals.

No! DigiSim.io runs entirely in your web browser. Simply visit our website and start designing circuits immediately. We recommend using a modern browser like Chrome, Firefox, Safari, or Edge for the best experience.

Yes! We offer a free tier that includes access to core simulator, basic & derived logic gates, I/O components, and essential tools. You can save up to 32 circuits in the cloud and access the first 4 SimCast lessons. For more advanced features and generous cloud storage, consider getting the DigiSim Pro.

Getting started is easy: Navigate to the Playground from the main menu, drag components from the component palette on the left to the workspace, connect components by clicking on output pins and dragging to input pins, use input switches and clocks to control your circuit, and watch output lights and displays show real-time results.

DigiSim.io works on any device with a modern web browser. It runs best on desktops and laptops (Windows, macOS, Linux, ChromeOS) where you have a mouse or trackpad for precise component placement and wiring. Tablets can be used for viewing and running simulations, but the design experience is optimized for larger screens with pointer input.

You can explore the Playground and build circuits without creating an account. However, creating a free account unlocks cloud saving so your circuits are stored securely and accessible from any device. An account is also required to access SimCast lessons and template circuits.

Yes! DigiSim includes a template circuits library with pre-built designs covering common topics like adders, counters, ALUs, and more. Templates are a great way to learn — you can open one, study how it works, modify it, and save your own version. Access templates from the File menu or the Templates section in the Playground.

DigiSim.io includes a comprehensive library: Basic Logic Gates (AND, OR, NOT, NAND, NOR, XOR, XNOR, Buffer), Input/Output (Switches, Constants, Output Lights, Seven-Segment Displays), Combinational Logic (Multiplexers, Demultiplexers, Encoders, Decoders), Arithmetic (Half/Full Adders, 4-bit and 8-bit Adders, ALUs, Comparators), Sequential Logic (Flip-Flops, Latches, Registers, Counters), Memory (RAM 256×8, ROM 256×8), CPU Components (Program Counter, Instruction Register, Control Unit), and Advanced (Assembly Program Loader, Oscilloscope, Pixel Screen).

Our platform includes both 4-bit and 8-bit versions of many components. 4-bit components are ideal for learning fundamental concepts and building smaller circuits, while 8-bit components are better for more realistic computer architecture projects and advanced simulations. Note that full CPU components and advanced 8-bit systems are available with the DigiSim Pro.

DigiSim.io uses an advanced event-driven simulation engine that accurately models signal propagation delays and timing behavior. This means you can observe realistic timing relationships, analyze sequential circuits, and understand how real digital systems operate.

The Assembly Program Loader allows you to write assembly code and automatically load it into RAM components. This is perfect for CPU projects where you want to test your processor design with actual programs. It supports a custom assembly language with standard instructions like LDA, STA, ADD, and JMP. This feature is available with the DigiSim Pro, which includes the full CPU component library.

DigiSim currently provides a curated library of over 50 professionally designed components. While you cannot create entirely new component types from scratch, you can combine existing components into subcircuits that act as reusable building blocks in larger designs. This lets you encapsulate common patterns — like an ALU or a register file — and reuse them without rebuilding each time.

The Seven-Segment Display is an output component that visually renders hexadecimal digits (0-F) just like the numeric displays found on real-world electronics such as clocks, calculators, and instrument panels. It accepts a multi-bit input and lights up the appropriate segments. It is great for visualizing counter outputs, ALU results, or memory contents in a human-readable way.

The Pixel Screen is an advanced output component that lets you drive a small grid of pixels from your circuit, enabling simple graphics output. It is commonly used in CPU projects to demonstrate video output or to create visual feedback beyond simple LEDs and seven-segment displays. The Pixel Screen is available with the DigiSim Pro.

Connecting components is intuitive: Click on an output pin (right side of components), drag to an input pin (left side of components), release to create the connection. Connected pins show their logic state with color coding (high/low/high-impedance).

Make sure you've properly connected all pins and that your input sources (switches, clocks) are set correctly. For sequential circuits, ensure clock signals are connected and that you understand the timing requirements. Use the debugging tools like the oscilloscope to analyze signal timing.

The clock component generates periodic signals essential for sequential circuits. Right-click on the clock to adjust its frequency. Connect the clock output to components that need timing signals, such as flip-flops, registers, and counters.

The Oscilloscope displays voltage waveforms over time and is perfect for analyzing timing relationships, debugging sequential circuits, understanding propagation delays, and verifying clock synchronization. The free tier includes basic timing analysis, while the DigiSim Pro provides an advanced 8-channel oscilloscope for complex analysis.

Building a CPU is one of our most advanced projects and requires the DigiSim Pro for access to the full CPU component library. Start with our demo circuits: Begin with the Program Counter and Clock, add ROM/RAM for instruction and data storage, include the Instruction Register and Control Unit, connect the ALU and processor registers, wire the address and data buses, and use the Assembly Program Loader to test with actual programs.

Start by checking the basics: verify every pin is connected (unconnected inputs float and cause unpredictable behavior), confirm your input switches are in the expected state, and look at the wire colors to trace signal values through the circuit. For sequential circuits, attach the Oscilloscope to key signals to inspect timing. You can also simplify by disconnecting sections of the circuit and testing them in isolation to locate the problem.

Yes. DigiSim's event-driven simulation engine models propagation delays so you can observe how signals ripple through your circuit over time. This is essential for understanding race conditions, setup/hold time violations, and why certain sequential designs require specific clocking strategies. Use the Oscilloscope to visualize these delays on a time axis.

Yes. DigiSim supports undo and redo in the Playground so you can freely experiment without fear of breaking your circuit. Use the standard keyboard shortcuts (Ctrl+Z to undo, Ctrl+Shift+Z or Ctrl+Y to redo) or the buttons in the toolbar to step back and forth through your recent actions.

You can save circuits in two ways: Local Save — use File → Export to download your circuit as a .digi file; Cloud Save — use File → Save (requires account) to store circuits in our cloud with automatic synchronization.

Save limits depend on your license: Free Tier allows 5 circuits in the cloud, and DigiSim Pro provides high-capacity cloud storage for thousands of circuits (subject to Fair Use Policy). Local exports (.digi files) have no limits for all users.

For legitimate human users, the limit is virtually unreachable. Our storage is designed to hold thousands of circuit diagrams — enough for a 4-year degree and beyond. However, to keep the service fast for everyone, we have anti-abuse measures in place to block automated bots or scripts from flooding our servers. As long as you are creating circuits manually, you don't need to worry about limits.

Currently, DigiSim.io uses its own .digi file format optimized for our simulation engine. While we don't directly import from other formats, you can recreate circuits quickly using our intuitive drag-and-drop interface.

You can share a circuit by exporting it as a .digi file (File → Export) and distributing that file via email, your LMS, or any file-sharing service. Recipients can then import the file into their own DigiSim Playground using File → Import. This makes it easy for professors to distribute starter circuits or for study groups to collaborate on projects.

If you reach your cloud storage limit on the free tier, you will not be able to create new cloud-saved projects until you free up space by deleting existing ones. You can always export any circuit as a local .digi file before deleting it from the cloud, so you never lose work. Upgrading to DigiSim Pro provides significantly more cloud storage.

Yes. DigiSim lets you organize your cloud-saved circuits into folders so you can group them by course, topic, or project. This is especially helpful when you accumulate many designs over a semester. You can rename, move, and delete folders from the project manager.

SimCast is DigiSim's interactive lesson format — guided tutorials that show step-by-step how to build and understand digital circuits. Each SimCast includes narrated instructions, automatic component placement and connection, educational explanations of circuit principles, and progressive complexity from basic gates to complete systems. The free tier includes access to the first 4 SimCast lessons, while the DigiSim Pro provides access to all 70+ SimCast lessons.

Absolutely! DigiSim.io is designed with education in mind: No software installation required, structured learning progression from basic to advanced concepts, built-in documentation for every component, and demo circuits demonstrating key concepts.

Our platform serves multiple educational levels: High School (basic logic gates and simple circuits), Undergraduate (sequential logic, computer architecture, processor design), Graduate (advanced timing analysis, complex system design), and Professional (prototyping and educational demonstration).

DigiSim is primarily a self-directed design and simulation tool rather than a full LMS. However, professors can distribute starter circuits via .digi files, have students submit their completed designs for review, and use the template library to set up consistent assignments. Students can export their work at any time, making it easy to submit through your institution's existing grading platform.

DigiSim does not include a built-in grading engine, but it pairs well with your existing course workflow. Professors commonly create a starter circuit, distribute it to students, and then collect the completed .digi files for manual or automated evaluation. Because circuits are saved as JSON-based files, tech-savvy instructors can write scripts to verify expected outputs programmatically.

SimCast lessons follow a structured curriculum that mirrors a typical digital logic course. Early lessons cover basic gates and truth tables, then progress through combinational logic, arithmetic circuits, latches and flip-flops, registers and counters, memory systems, and ultimately full CPU design. Each lesson builds on concepts from previous ones, so working through them in order is recommended.

DigiSim Pro is available as a monthly or yearly subscription. Your subscription automatically renews at the end of each billing period. You can cancel anytime through your account settings or the Stripe billing portal, and you'll keep access until the end of your current billing period.

You will NEVER lose your projects. If you cancel or your subscription expires, your account reverts to the Free tier: You CAN still log in, view your circuits, run simulations, and export your files. You will have limited access to premium components and features. Your data remains safe and accessible.

Yes. You can switch between monthly and yearly billing at any time through the Stripe billing portal. When switching to yearly, you save approximately 20% compared to monthly billing.

We have a strict "No Data Lock-in" policy. You can download your source files (JSON) at any time. Even if our servers go offline, you possess the raw data of your designs. We guarantee a minimum 30-day notice period with full export access before any shutdown.

Absolutely! DigiSim is widely used in university courses. Even on the Free tier, you can still show your designs to future employers or professors. Upgrading to DigiSim Pro unlocks all components and lessons for your coursework.

We're committed to supporting education. Contact our team at education@digisim.io to discuss educational pricing for schools, universities, and qualified educational institutions.

We accept payments through Stripe, which supports major credit cards, debit cards, and various local payment methods. All transactions are secure and encrypted.

Subscription fees are generally non-refundable, except as required by law. You can cancel anytime and keep access until the end of your billing period. We encourage you to fully explore the free tier before subscribing to ensure DigiSim meets your needs.

The Free tier is available to all users, including those with expired or cancelled subscriptions. On the Free tier you can still log in, open all of your saved circuits, run simulations, and export .digi files. You have limited access to premium components and features. Your work remains accessible indefinitely on the Free tier.

The free tier gives you access to basic and derived logic gates, I/O components, essential tools, basic oscilloscope analysis, up to 5 cloud-saved circuits, and the first 4 SimCast lessons. DigiSim Pro unlocks the full component library including 8-bit components, CPU parts, RAM, ROM, the Assembly Program Loader, the advanced 8-channel oscilloscope, the Pixel Screen, all 70+ SimCast lessons, and high-capacity cloud storage.

No. Each DigiSim Pro license is tied to a single user account and is not transferable. However, we offer educational pricing for institutions that need to provision multiple seats. Contact education@digisim.io for volume pricing information.

DigiSim.io works best on modern browsers: Recommended: Chrome 90+, Firefox 88+, Safari 14+, Edge 90+. Required: JavaScript enabled, minimum 1GB RAM. Optimal: 1920×1080 resolution or higher for the best workspace experience.

For optimal performance: Use a modern browser with hardware acceleration enabled, close unnecessary browser tabs and applications, for large circuits consider breaking them into smaller subcircuits, disable browser extensions that might interfere, and ensure stable internet connection for cloud features.

We value your feedback! You can email us directly at support@digisim.io, use the feedback button in the application, include steps to reproduce any issues, and attach relevant circuit files if applicable.

Yes, we take data security seriously: All data transmission is encrypted using HTTPS, cloud-saved circuits are stored securely with regular backups, we never share your circuits or personal information with third parties, and you maintain full ownership of your circuit designs.

No problem! Use the "Forgot Password" link on the login page to reset your password. You'll receive an email with instructions to create a new password and regain access to your account and saved circuits.

DigiSim requires an internet connection to load the application, authenticate your account, and sync cloud-saved circuits. Once the Playground is loaded, basic circuit design and simulation will continue to work if your connection drops temporarily, but you will not be able to save to the cloud or access SimCast lessons until connectivity is restored. For offline backup, export your circuits as .digi files which can be stored locally.

DigiSim is optimized for desktop and laptop browsers where you have a mouse or trackpad for precise wiring and component placement. While the application will load on tablets, the design experience is best on screens 1024px or wider. Mobile phones are not recommended for circuit design due to the small screen size, though you can view and run previously built circuits on any device.

DigiSim supports standard shortcuts to speed up your workflow: Ctrl+Z / Cmd+Z to undo, Ctrl+Shift+Z / Cmd+Shift+Z to redo, Ctrl+S / Cmd+S to save, Ctrl+C / Cmd+C and Ctrl+V / Cmd+V to copy and paste components, Delete or Backspace to remove selected components, and scroll wheel to zoom in and out on the workspace.