Zo Computer gives you a personal cloud server where you can run code, build projects, and host services. Every Zo comes with a built-in terminal and file system you can use right from your browser—plus an AI assistant that can help you set things up.
One thing you can run is a spaced repetition system for learning. If you've never heard of spaced repetition, it's a learning technique where you review information at increasing intervals—seeing a flashcard right before you'd forget it, then waiting longer before the next review. It's one of the most effective ways to commit things to long-term memory, backed by decades of cognitive science research.
Why spaced repetition works
Spaced repetition takes advantage of how memory works. When you encounter information at just the right time—not too soon, not too late—you strengthen the neural pathways that encode it. Review too often and you waste time. Review too late and you've already forgotten. The "spacing effect" optimizes this timing.
People use spaced repetition to learn:
Languages — vocabulary, grammar patterns, phrases
Medicine — anatomy, pharmacology, diagnoses
Programming — APIs, syntax, algorithms
History, law, music theory — anything with facts to remember
The most popular spaced repetition app is Anki, which has been around since 2006. But Anki stores your cards in a database, and some people prefer something simpler.
Hashcards: flashcards as plain text
Hashcards is a newer spaced repetition system by Fernando Borretti that takes a different approach: your flashcards are just markdown files in a folder.
A deck looks like this:
Q: What is the capital of France?
A: Paris
Q: What year did World War II end?
A: 1945
C: The mitochondria is the [powerhouse] of the cell.
That's it. Q: and A: for question-answer cards, C: with [brackets] for cloze deletions (fill-in-the-blank). No special format, no database—just text files you can edit with any editor, sync with Git, and back up however you like.
Hashcards uses FSRS (Free Spaced Repetition Scheduler), the same modern algorithm now available in Anki. It's more accurate than older algorithms at predicting when you'll forget something.
Why plain text matters
Storing flashcards as markdown has real advantages:
Edit with any tool. Use VS Code, Vim, Obsidian—whatever you prefer. No proprietary editor.
Version control. Put your cards in a Git repo. Track changes, branch experiments, collaborate.
Generate cards programmatically. Write a script to turn a CSV of vocabulary into a deck, or use an LLM to create cards from your notes.
Portable forever. Markdown is a 20-year-old format that will outlast any app. Your learning data won't be trapped.
Share on GitHub. Make your flashcard collection public for others to learn from.
As Borretti writes: "Markdown files in a Git repo gives me a level of ownership that other approaches lack."
Setting up hashcards on Zo
Zo has a setup prompt that installs and configures hashcards for you. Tell your AI to run it, and within a few minutes you'll have:
Hashcards installed and running at
https://srs-yourname.zocomputer.ioA flashcards directory at
/home/workspace/flashcards/with a sample deckA persistent service that auto-restarts if it crashes
The prompt handles installing Rust (hashcards is written in Rust), building from source, creating directories, and registering the service. You don't need to touch a Dockerfile or configure a reverse proxy.
Creating flashcards
Once hashcards is running, create .md files in /home/workspace/flashcards/. Each file is a deck.
Basic question-answer cards:
Q: What does FSRS stand for?
A: Free Spaced Repetition Scheduler
Cloze deletions (text in brackets is hidden during review):
C: [Spaced repetition] is a learning technique that involves reviewing information at [increasing intervals].
You can also add images, audio, and LaTeX math. See the hashcards documentation for the full syntax.
Tip: Ask your Zo AI to help create flashcards. "Convert these notes into hashcards format" or "Create 10 flashcards about JavaScript promises" works well.
Hashcards vs Anki
Both are excellent tools. Here's how they compare:
Anki — The gold standard. Massive plugin ecosystem, mobile apps, cross-device sync. Uses a database format. Best if you want polished apps and don't mind the complexity.
Hashcards — Plain-text storage, modern FSRS algorithm, minimal interface. Best if you value simplicity, version control, and ownership of your data.
Mochi — Markdown-based like hashcards, with a more polished interface. Cloud-hosted with a subscription, or self-hostable.
RemNote — Combines note-taking with flashcards. More complex, aimed at knowledge management.
If you're happy with Anki, there's no need to switch. But if you've been frustrated by Anki's complexity, or you want your flashcards in Git alongside your notes, hashcards is worth trying.
What else can you run on Zo?
Hashcards is one of many tools you can self-host on your Zo Computer:
Workflow automation like n8n
VS Code in your browser with code-server
Remote development with your favorite IDE over SSH
Databases like PostgreSQL, SQLite, or Redis
Websites and APIs you build
Your AI assistant can help you set up and manage any of these.
Resources
Hashcards on GitHub — Source code and documentation
Hashcards: A Plain-Text Spaced Repetition System — Fernando Borretti's blog post explaining the design
Hacker News discussion — Community reactions and ideas
Zo hashcards setup prompt — One-click installation
FSRS algorithm — How the scheduling works
Augmenting Long-term Memory — Michael Nielsen's essay on using spaced repetition effectively