A full Apple II system implemented in RHDL — 6502 CPU, 48KB RAM, video output, Disk II controller, keyboard, and speaker.
System Architecture
The Apple II system integrates multiple components into a complete working computer:
- 6502 CPU — the processor core (see Building a 6502)
- 48KB RAM — main memory with language card support
- Text/Graphics Video — 40-column text and lo-res/hi-res graphics modes
- Disk II Controller — floppy disk interface with Woz Machine state machine
- Keyboard — ASCII keyboard encoder with strobe
- Speaker — 1-bit audio toggle
Memory Map
$0000-$BFFF 48KB RAM
$C000-$C0FF I/O space (keyboard, speaker, switches)
$C100-$CFFF Peripheral card ROM
$D000-$FFFF Monitor ROM / Language Card RAM
Video System
The video generator implements Apple II’s unique memory-interleaved display:
- Text mode — 40x24 characters, normal and inverse
- Lo-res graphics — 40x48 color blocks (16 colors)
- Hi-res graphics — 280x192 pixels (6 colors)
Browser Simulation
The complete system runs in the browser via WASM. Load disk images, type on the keyboard, and watch the video output — all simulated at the gate level in real time.