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/trackdisk.md

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+[← Home](../README.md) · [Devices](README.md)
+
+# trackdisk.device — Floppy Disk I/O
+
+## Overview
+
+`trackdisk.device` provides raw sector I/O for Amiga floppy drives. Each drive is a unit (0–3). The device operates on 512-byte sectors, 11 sectors per track (880 KB DD disks) or 22 per track (1760 KB HD).
+
+---
+
+## Opening
+
+```c
+struct IOExtTD *tdreq = (struct IOExtTD *)
+    CreateIORequest(port, sizeof(struct IOExtTD));
+OpenDevice("trackdisk.device", 0, (struct IORequest *)tdreq, 0);
+```
+
+---
+
+## Commands
+
+| Code | Constant | Description |
+|---|---|---|
+| 2 | `CMD_READ` | Read sectors |
+| 3 | `CMD_WRITE` | Write sectors |
+| 4 | `CMD_UPDATE` | Flush write buffer to disk |
+| 9 | `TD_MOTOR` | Turn motor on/off |
+| 10 | `TD_FORMAT` | Low-level format track |
+| 11 | `TD_SEEK` | Move head to track |
+| 12 | `TD_REMOVE` | Notify on disk change |
+| 13 | `TD_CHANGENUM` | Get disk change count |
+| 14 | `TD_CHANGESTATE` | Check if disk present |
+| 15 | `TD_PROTSTATUS` | Check write-protect |
+| 16 | `TD_RAWREAD` | Read raw MFM data |
+| 17 | `TD_RAWWRITE` | Write raw MFM data |
+| 18 | `TD_GETDRIVETYPE` | Get drive type |
+| 19 | `TD_GETNUMTRACKS` | Get total tracks |
+| 20 | `TD_ADDCHANGEINT` | Add disk change interrupt |
+| 21 | `TD_REMCHANGEINT` | Remove disk change interrupt |
+
+---
+
+## Reading a Sector
+
+```c
+UBYTE buf[512];
+tdreq->iotd_Req.io_Command = CMD_READ;
+tdreq->iotd_Req.io_Data    = buf;
+tdreq->iotd_Req.io_Length  = 512;
+tdreq->iotd_Req.io_Offset  = 0;   /* byte offset = sector * 512 */
+DoIO((struct IORequest *)tdreq);
+```
+
+---
+
+## Disk Geometry
+
+| Parameter | DD (880 KB) | HD (1760 KB) |
+|---|---|---|
+| Heads | 2 | 2 |
+| Cylinders | 80 | 80 |
+| Sectors/track | 11 | 22 |
+| Bytes/sector | 512 | 512 |
+| Total sectors | 1760 | 3520 |
+
+Byte offset = `(cylinder * 2 + head) * sectors_per_track * 512 + sector * 512`
+
+---
+
+## References
+
+- NDK39: `devices/trackdisk.h`
+- ADCD 2.1: trackdisk.device autodocs