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/ocs_a500/README.md

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+[← Home](../../README.md) · [Hardware](../README.md)
+
+# OCS Chipset — A500 / A1000 / A2000
+
+## Overview
+
+The **Original Chip Set** (OCS) ships in the Amiga 1000 (1985), A500 (1987), and early A2000 boards. It consists of three custom chips: **Agnus**, **Denise**, and **Paula**, supported by the MOS 8520 CIA pair.
+
+## Chip Summary
+
+| Chip | MOS Part | Primary Responsibilities |
+|---|---|---|
+| **Agnus** | 8361 (PAL), 8367 (NTSC) | DMA controller, Copper coprocessor, Blitter, address generation |
+| **Denise** | 8362 | Display: bitplane fetch decode, sprite decode, colour output |
+| **Paula** | 8364 | Audio DMA (4 channels), floppy disk I/O, serial port, interrupts |
+
+## Contents
+
+| File | Topic |
+|---|---|
+| [chipset_ocs.md](chipset_ocs.md) | Chip internals, DMA priorities, bus arbitration |
+| [custom_registers.md](custom_registers.md) | Full OCS register map $DFF000–$DFF1FE |
+| [copper.md](copper.md) | Copper coprocessor: WAIT/SKIP/MOVE, copperlist format |
+| [blitter.md](blitter.md) | Blitter: channels A/B/C/D, minterms, line mode, fill |
+| [paula_audio.md](paula_audio.md) | Audio DMA: AUDxLCH/LCL/LEN/PER/VOL, interrupt |
+| [paula_serial.md](paula_serial.md) | Serial port: SERPER/SERDATR, baud rate |
+| [sprites.md](sprites.md) | Hardware sprites: SPRxPTH, control words, attach mode |
+
+## OCS Limitations vs ECS/AGA
+
+- Max **512 KB Chip RAM** on A500 rev 5 and earlier (Agnus 8361/8367 addresses 512 KB only)
+- A500 rev 6+ allows 1 MB with Fat Agnus (part of later OCS run)
+- No productivity display modes (ECS adds BEAMCON0)
+- 32 colours max (or 64 EHB, or HAM 12-bit) in standard bitplane modes
+- Blitter is 16-bit; no 64-bit fetch (AGA adds FMODE)
+- No ECS Denise border features
+
+## References
+
+- ADCD 2.1 Hardware Manual: http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node0000.html
+- *Amiga Hardware Reference Manual* 3rd ed., Chapter 5–8