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.

07_dos/environment.md

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+[← Home](../README.md) · [AmigaDOS](README.md)
+
+# Environment Variables — GetVar, SetVar
+
+## Overview
+
+AmigaDOS supports both **local** (per-process) and **global** (system-wide) environment variables. Local variables are stored in the process's `pr_LocalVars` MinList; global variables are stored as files in `ENV:` (RAM-backed) and `ENVARC:` (persistent on disk).
+
+---
+
+## API
+
+| LVO | Function | Description |
+|---|---|---|
+| −900 | `GetVar(name, buf, size, flags)` | Read a variable |
+| −906 | `SetVar(name, buf, size, flags)` | Set or create a variable |
+| −912 | `DeleteVar(name, flags)` | Remove a variable |
+| −918 | `FindVar(name, type)` | Find a LocalVar node |
+
+### Flags
+
+```c
+/* dos/var.h — NDK39 */
+#define GVF_GLOBAL_ONLY   0x100   /* search only ENV: */
+#define GVF_LOCAL_ONLY    0x200   /* search only pr_LocalVars */
+#define GVF_BINARY_VAR    0x10    /* treat value as binary data */
+#define GVF_DONT_NULL_TERM 0x20   /* don't null-terminate result */
+#define LV_VAR            0       /* standard variable */
+#define LV_ALIAS          1       /* shell alias */
+```
+
+---
+
+## Usage
+
+```c
+/* Set a global variable: */
+SetVar("EDITOR", "ed", -1, GVF_GLOBAL_ONLY);
+
+/* Read it back: */
+char buf[256];
+if (GetVar("EDITOR", buf, sizeof(buf), 0) >= 0) {
+    Printf("EDITOR = %s\n", buf);
+}
+
+/* Delete: */
+DeleteVar("EDITOR", GVF_GLOBAL_ONLY);
+```
+
+---
+
+## Storage Locations
+
+| Scope | Storage | Persistent? |
+|---|---|---|
+| Local | `pr_LocalVars` MinList (in-memory) | No — dies with process |
+| Global (volatile) | `ENV:` — assign to `RAM:Env/` | No — lost on reboot |
+| Global (persistent) | `ENVARC:` — assign to `SYS:Prefs/Env-Archive/` | Yes — survives reboot |
+
+The startup-sequence copies `ENVARC:` to `ENV:` at boot.
+
+---
+
+## References
+
+- NDK39: `dos/var.h`
+- ADCD 2.1: `GetVar`, `SetVar`, `DeleteVar`