Three Modes, One IDE
Assembly, BASIC, and Code — switch between them with a click. Each mode has its own file tabs, editor, and reference panels. Learn how computers really work, then build something real.
Assembly — Write Machine Code
A simple 8-bit CPU with 36 instructions. Load values into registers, do math, branch on flags, and draw pixels on a 64x48 graphics display. Step through one instruction at a time and watch everything change.
Live Graphics Output
Built-In Reference
BASIC — The Language of the 1980s
A green-screen terminal with a > prompt. Type BASIC just like on a TRS-80, Apple II, or Commodore 64. Write programs with line numbers, run them instantly, and draw graphics with PLOT, DRAW, and CIRCLE.
BASIC Graphics
BASIC Reference
Code — A Modern Editor
Syntax highlighting for 25 languages. Multiple file tabs, find/replace, autocomplete, bracket matching, and up to 4 concurrent terminal sessions. Everything you need for real-world coding alongside the retro stuff.
Multiple File Tabs
25 Languages
Terminal Panel
Multiple Terminals
Per-Mode File Tabs
Every mode gets its own set of file tabs — up to 5 per mode. Switch between files, name them, save them, and pick up right where you left off. Session recovery survives crashes and reboots.
Assembly Tabs
BASIC Tabs
AI Integration Experimental
Chat with Claude or GitHub Copilot inside RetroCode. Your AI assistant can write code, run scripts, manage files, and switch between 11 models — all through the built-in chat panel. This feature is in active development.
🤖 Claude (via MCP)
Uses your Claude Max/Pro subscription through Claude Code CLI.
- In RetroCode: Code → MCP tab → Install
claude mcp add retrocode node ~/mcp-server.js- Type
/retrocode in Claude Code
✈️ GitHub Copilot (via SDK)
Uses your Copilot subscription. Choose from GPT-4.1, Claude, Gemini, and more.
npm i -g @github/copilot @github/copilot-sdkcopilot -i "auth login"node ~/copilot-bridge.js --model gpt-4.1
💬 Chat
Talk through the RetroCode chat panel. Your AI responds in real time inside the app.
✏️ Write Code
AI writes directly in your editor with full syntax highlighting for 25 languages.
💾 Save Files
Save files to disk from the editor. Create and manage your project files via chat.
▶️ Run Scripts
Execute programs in the embedded terminal. Run assembly, BASIC, or any script.
📖 Read Your Code
AI reads and understands what you've written, then suggests improvements.
🔀 Switch Modes
Move between Assembly, BASIC, and Code editor. Manage tabs and create new files.
23 MCP Tools
| Category | Tools |
|---|
| Editor | get_editor, set_editor, append_editor |
| Files | save_file, read_file |
| Tabs | list_tabs, switch_tab, new_tab |
| Terminal | open_terminal, close_terminal, terminal, terminal_output |
| Chat | chat, get_chat, heartbeat |
| Control | run, stop, switch_mode, get_mode |
| Reference | asm_reference, basic_reference |
| System | health, list_languages |
Features
8-Bit CPU Simulator
36 instructions: arithmetic, logic, branching, stack, I/O, and graphics. Two registers (A, B), 256 bytes of memory, zero and carry flags.
BASIC V2.0 Interpreter
40+ commands including PRINT, INPUT, FOR/NEXT, GOSUB, arrays, DATA/READ, PEEK/POKE, virtual file system, and INKEY$ for real-time games.
64x48 Graphics Display
Bitmap display with PLOT, DRAW, CIRCLE, BOX, FILL. Draw sine waves, fractals, games, and animations.
51 Lessons
26 assembly lessons and 25 BASIC lessons. Start from scratch and build up to drawing graphics and writing complete programs.
50+ Sample Programs
19 ASM examples and 35 BASIC samples — Snake, Breakout, math plots, trig functions, and diagnostic suites.
Label Support
The assembler supports labels for jump targets — no manual address counting. Write readable code with LOOP:, DONE:, SKIP:.
Step-Through Debugging
Execute one instruction at a time. Watch registers change, flags toggle, and the program counter advance through your code.
6 Themes
Default (green terminal), Standard, Dark, Light, RPG, and High Contrast. Choose your aesthetic.
File Save/Load
Save and load .asm, .bas, and .hex files. Your programs are real files you can share and edit.
Code Editor Mode
A full-featured text editor with syntax highlighting for 25 languages — C, C++, Java, Python, Rust, Go, Swift, Kotlin, Ruby, and more. Includes find/replace, autocomplete, bracket matching, go-to-line, comment toggle, and word wrap.
Multiple Terminals
Up to 4 concurrent terminal sessions with tab switching. Built-in xterm.js with shell selection, available in all three modes.
File Browser
Directory tree navigation for opening and managing files directly within the IDE.
AI Chat (Claude + Copilot + MorselHub)
Choose Claude, GitHub Copilot, or MorselHub as your AI provider. MorselHub adds iMessage and webhook support. Write code, run scripts, manage files — all from the built-in chat panel.
Per-Mode File Tabs
Up to 5 file tabs in each mode — Assembly, BASIC, and Code. Independent content, session recovery, and full keyboard shortcuts.
Assembly Instruction Set
The CPU has 36 instructions organized into 7 categories. All values are 8-bit (0x00 to 0xFF).
| Hex | Mnemonic | Description |
|---|
| Data Movement |
| 00 | NOP | No operation |
| 01 | LDA addr | Load A from memory address |
| 02 | LDI val | Load immediate value into A |
| 03 | STA addr | Store A to memory address |
| 04 | LDB addr | Load B from memory address |
| 05 | LBI val | Load immediate value into B |
| 06 | STB addr | Store B to memory address |
| 07 | MOV | Copy A to B |
| Arithmetic |
| 10 | ADD | A = A + B |
| 11 | SUB | A = A - B |
| 12 | INC | A = A + 1 |
| 13 | DEC | A = A - 1 |
| 14 | ADI val | A = A + immediate |
| 15 | MUL | A = A * B |
| 16 | DIV | A = A / B |
| 17 | MOD | A = A % B |
| 18 | PUSH | Push A onto stack |
| 19 | POP | Pop stack into A |
| Logic |
| 20 | AND | A = A AND B |
| 21 | OR | A = A OR B |
| 22 | XOR | A = A XOR B |
| 23 | NOT | A = NOT A |
| 24 | SHL | Shift A left |
| 25 | SHR | Shift A right |
| 26 | CPI val | Compare A with immediate |
| Compare & Branch |
| 30 | CMP | Compare A with B |
| 31 | JMP addr | Jump to address |
| 32 | JZ addr | Jump if zero flag set |
| 33 | JNZ addr | Jump if zero flag clear |
| 34 | JC addr | Jump if carry flag set |
| I/O & Graphics |
| 40 | OUT | Output A to display |
| 41 | INP | Input to A |
| 50 | PLT | Plot pixel at (A, B) |
| 51 | UPL | Unplot pixel at (A, B) |
| 52 | CLG | Clear graphics |
| FF | HLT | Halt |
BASIC V2.0
A complete BASIC interpreter with 40+ commands, math and string functions, graphics, and a virtual file system.
10 PRINT "HELLO WORLD"
20 LET A = 5
30 FOR I = 1 TO 10
40 PRINT I; " x "; A; " = "; I * A
50 NEXT I
60 PRINT ""
70 PRINT "DONE!"
80 END
Commands
PRINT, INPUT, LET, GOTO, IF/THEN, FOR/NEXT/STEP, GOSUB/RETURN, REM, END, CLS, DIM, DATA/READ/RESTORE, ON GOTO/GOSUB, STOP/CONT, POKE/PEEK
Math Functions
INT, RND, ABS, SQR, SGN, SIN, COS, TAN, LOG, EXP
String Functions
LEN, LEFT$, RIGHT$, MID$, CHR$, ASC, TAB, VAL, STR$
Game Input
INKEY$ — non-blocking key detection for real-time games. Supports arrow keys, WASD, SPACE, ENTER, ESC, and all printable characters. Game loops run at ~60fps.
Graphics (64x48 bitmap)
PLOT, UNPLOT, DRAW, CIRCLE, BOX, FILL, GCLS, COLOR, LOCATE
Virtual Files
SAVE$, LOAD$, DIR, DEL — persistent storage in the browser
Why RetroCode?
In 7th grade, Senzall's dad surprised him with a TRS-80 Color Computer — powered by the Motorola 6809 CPU that his dad's team at Motorola helped build. Before that, he'd been writing BASIC programs at Radio Shack store windows since age 12. By 1983 he had an IBM PC, learning 8088 assembly and Turbo Pascal.
RetroCode recreates that experience for a new generation. The same hands-on learning — loading registers, branching on flags, plotting pixels — but now with Claude or GitHub Copilot as your coding partner. Ask it to explain an instruction, write a BASIC game, or debug your assembly code. It's 1980s computing meets 2026 AI.
Documentation
Full documentation is available in the app (Learn tab + Reference panels) and online:
System Requirements
- macOS: 12.0 or later (Apple Silicon)
- Windows: 11 or later (64-bit)
Free to download and use. No account required. No internet required after download.
