docs(amiga): complete AmigaOS 3.1/3.2 developer reference — 172 files across 17 sections

Comprehensive technical documentation covering:
- Hardware: OCS/ECS/AGA custom chip registers, Copper & Blitter deep dives
- Boot sequence: cold boot through startup-sequence
- Binary format: HUNK executable spec, relocation, debug info
- Linking & ABI: .fd files, LVO tables, register calling conventions
- Exec kernel: tasks, interrupts, memory, signals, semaphores
- AmigaDOS: file I/O, FFS/OFS layout, CLI/Shell scripting
- Graphics: planar bitmaps, Copper programming, HAM/EHB modes
- Intuition: screens, windows, IDCMP, BOOPSI
- Devices: trackdisk, SCSI, serial, timer, audio, keyboard
- Libraries: utility, expansion, IFFParse, locale, ARexx
- Networking: bsdsocket API, SANA-II, TCP/IP stack comparison
- Toolchain: GCC, vasm/vlink, SAS/C, NDK, debugging
- Reverse engineering: IDA/Ghidra setup, compiler fingerprints, case studies
- CPU & MMU: 68040/060 emulation libs, PMMU, cache management
- Driver development: SANA-II, Picasso96/RTG, AHI audio

All files include breadcrumb navigation. No local paths or proprietary content.

10_devices/audio.md

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+[← Home](../README.md) · [Devices](README.md)
+
+# audio.device — DMA Audio Channels
+
+## Overview
+
+`audio.device` provides access to the Amiga's 4 DMA audio channels. Each channel plays 8-bit PCM samples from Chip RAM at programmable rates.
+
+---
+
+## Channel Allocation
+
+```c
+UBYTE allocationMap[] = { 1, 2, 4, 8 }; /* channel masks */
+struct IOAudio *aio = (struct IOAudio *)
+    CreateIORequest(port, sizeof(struct IOAudio));
+aio->ioa_Request.io_Message.mn_Node.ln_Pri = 0;
+aio->ioa_Data    = allocationMap;
+aio->ioa_Length  = sizeof(allocationMap);
+OpenDevice("audio.device", 0, (struct IORequest *)aio, 0);
+/* aio->ioa_AllocKey = allocation key for this channel */
+```
+
+---
+
+## Playing a Sample
+
+```c
+aio->ioa_Request.io_Command = CMD_WRITE;
+aio->ioa_Request.io_Flags   = ADIOF_PERVOL;
+aio->ioa_Data    = sampleData;    /* MUST be in Chip RAM */
+aio->ioa_Length  = sampleLength;  /* in bytes */
+aio->ioa_Period  = 428;           /* ~8287 Hz (PAL) */
+aio->ioa_Volume  = 64;           /* 0–64 */
+aio->ioa_Cycles  = 1;            /* 0 = loop forever */
+BeginIO((struct IORequest *)aio);
+```
+
+### Period Calculation
+
+```
+Period = clock_constant / desired_frequency
+PAL:  clock = 3546895 Hz → Period = 3546895 / freq
+NTSC: clock = 3579545 Hz → Period = 3579545 / freq
+```
+
+| Frequency | Period (PAL) |
+|---|---|
+| 8287 Hz | 428 |
+| 11025 Hz | 322 |
+| 22050 Hz | 161 |
+| 28867 Hz | 124 (minimum safe) |
+
+---
+
+## Channel Registers
+
+| Channel | Address | Description |
+|---|---|---|
+| 0 | `$DFF0A0` | AUD0 (left) |
+| 1 | `$DFF0B0` | AUD1 (right) |
+| 2 | `$DFF0C0` | AUD2 (right) |
+| 3 | `$DFF0D0` | AUD3 (left) |
+
+Each channel: pointer (PTH/PTL), length (LEN), period (PER), volume (VOL).
+
+---
+
+## References
+
+- NDK39: `devices/audio.h`
+- HRM: audio DMA chapter