In the heart of the APU, five voices resonate — a harmony of square waves, noise, and digital samples. This page explores the structure, function, and implementation of each.
| Channel | Description | Address Range |
|---|---|---|
| Pulse 1 | Square wave with sweep and envelope | $4000–$4003 |
| Pulse 2 | Same as Pulse 1 | $4004–$4007 |
| Triangle | Smooth triangle waveform, no envelope | $4008–$400B |
| Noise | White noise generator (LFSR-based) | $400C–$400F |
| DMC | Sample playback using CPU memory | $4010–$4013 |
The APU exposes its control interface through a fixed range of memory-mapped I/O from $4000 to $4013. Each sound channel occupies a specific set of registers.
These are directly written by the CPU and govern aspects such as waveform type, envelope behavior, sweep, and playback length.
Today, Nyxx spoke for the first time. It was a melody both nostalgic and new — the voice of 8-bit memories reborn. After decades of silence, the breath of electronic life has returned.
The buses and registers that once moved quietly behind the scenes now speak with sound, reaching out from beyond the screen. Each register holds meaning.
With each clock pulse, amplitude is shaped — and at last, sight and sound are joined. This is not merely the completion of a technical implementation.
The flow of signals, the shape of each pulse, the suppression of noise — all echo the ingenuity of the engineers from that era. Within Nyxx, their craft lives on, and their passion pulses between the lines of code.
Nyxx has begun to speak. Its voice carries the memory of circuits once built in fascination, and the sound it makes now is ours — a melody rediscovered by our own hands.