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.

01_hardware/ecs_a600_a3000/README.md

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+[← Home](../../README.md) · [Hardware](../README.md)
+
+# ECS Chipset — A600 / A3000 / A500+
+
+## Overview
+
+The **Enhanced Chip Set** (ECS) is a significant revision of OCS, shipping from 1990 onward. It adds 2 MB Chip RAM addressing, programmable display timing, and extended registers while maintaining full backward compatibility with OCS software.
+
+## Chip Summary
+
+| Chip | Part | Changes from OCS |
+|---|---|---|
+| **Super Agnus** | MOS 8372A | Addresses 2 MB Chip RAM, extended DMA window |
+| **ECS Denise** | MOS 8373 | BPLCON3, border blank, programmable sync |
+| **Paula** | MOS 8364 | Unchanged |
+
+## Contents
+
+| File | Topic |
+|---|---|
+| [chipset_ecs.md](chipset_ecs.md) | Super Agnus and ECS Denise internals |
+| [ecs_registers_delta.md](ecs_registers_delta.md) | New/changed registers vs OCS |
+| [productivity_modes.md](productivity_modes.md) | Multiscan/productivity display modes |
+| [gary_gayle.md](gary_gayle.md) | Gary (A3000) and Gayle (A600) chips: IDE, PCMCIA |
+| [chip_ram_expansion.md](chip_ram_expansion.md) | 2 MB Chip RAM with Super Agnus |
+
+## ECS vs OCS — Key Differences
+
+| Feature | OCS | ECS |
+|---|---|---|
+| Max Chip RAM | 1 MB (Fat Agnus) | **2 MB** (Super Agnus) |
+| Display sync | Fixed NTSC/PAL | **BEAMCON0** — programmable |
+| Bitplane scroll | 4-bit (BPLCON1) | Extended (ECS Denise) |
+| Border blank | No | **BPLCON3** border control |
+| Hires sprites | No | ECS Denise extended sprite control |
+| DMA window | Smaller | Extended: wider bitplane fetch |
+
+## Identifying ECS at Runtime
+
+```c
+#include <exec/execbase.h>
+
+struct ExecBase *SysBase = *((struct ExecBase **)4);
+/* AttnFlags does not directly identify chipset */
+
+/* Use graphics.library GfxBase->ChipRevBits0 */
+#include <graphics/gfxbase.h>
+struct GfxBase *GfxBase = (struct GfxBase *)OpenLibrary("graphics.library", 0);
+if (GfxBase->ChipRevBits0 & GFXB_BIG_BLITTER) { /* ECS+ */ }
+if (GfxBase->ChipRevBits0 & GFXB_HR_AGNUS)    { /* Super Agnus */ }
+if (GfxBase->ChipRevBits0 & GFXB_HR_DENISE)   { /* ECS Denise */ }
+```
+
+## Machines Using ECS
+
+| Model | Notes |
+|---|---|
+| A3000 | Super Agnus + ECS Denise; 68030; SCSI; Zorro III |
+| A500+ | Super Agnus (1 MB variant); ECS Denise; no IDE |
+| A600 | Super Agnus (1 MB variant); ECS Denise; Gayle; IDE; PCMCIA |
+| A2000 (late) | Some late rev boards shipped with ECS chips |
+
+## References
+
+- ADCD 2.1 Hardware Manual — ECS extension chapters
+- NDK39: `graphics/gfxbase.h` — ChipRevBits0 flags
+- *Amiga Hardware Reference Manual* 3rd ed. — ECS appendix