Released in 1980 by Tandy Corporation. The CoCo used the Motorola 6809E CPU and MC6847 Video Display Generator.
This emulator faithfully simulates the 6-bit DAC at port $FF20 and generates real FSK (Frequency Shift Keying) audio output via the Web Audio API:
When you press PLAY on a loaded .CAS file, you'll hear the authentic cassette loading sounds — the same warbling tones that CoCo owners heard in the 1980s!
Uses the exact MC6847 VDG character generator ROM data — 128 characters rendered pixel-perfectly.
The emulator faithfully emulates the cassette motor relay at PIA1 Control Register A bit 3. When software starts or stops the tape motor, you'll hear the authentic relay "click" — the same satisfying sound CoCo owners heard when loading programs. The motor LED and state indicator track the relay in real time.
Load recorded .WAV files of real cassette tapes! The emulator performs FSK demodulation by analyzing zero-crossings in the audio waveform to extract the original data. Volume levels in the recording affect decode quality, just like on real hardware.
Click-free 6-bit DAC with ring buffer interpolation, DC offset removal, and dedicated FSK oscillator for cassette playback. The FSK visualizer shows the real-time waveform being generated. Motor relay clicks are synthesized from impulse response modeling of the original relay solenoid.