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.

09_intuition/screens.md

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+[← Home](../README.md) · [Intuition](README.md)
+
+# Screens — OpenScreen, CloseScreen, SA_ Tags
+
+## Overview
+
+An Amiga **Screen** is a complete display context: a `ViewPort` with its own `BitMap`, colour palette, and resolution. Multiple screens can coexist and be dragged up/down to reveal each other.
+
+---
+
+## Screen Types
+
+| Type | Constant | Description |
+|---|---|---|
+| Workbench | `WBENCHSCREEN` | The default desktop screen |
+| Custom | `CUSTOMSCREEN` | Application-owned screen |
+| Public | `PUBLICSCREEN` | Named screen other apps can open windows on |
+
+---
+
+## Opening a Screen (OS 2.0+ TagList)
+
+```c
+struct Screen *scr = OpenScreenTags(NULL,
+    SA_Width,       640,
+    SA_Height,      256,
+    SA_Depth,       4,           /* 16 colours */
+    SA_DisplayID,   HIRES_KEY,
+    SA_Title,       "My Screen",
+    SA_ShowTitle,   TRUE,
+    SA_Type,        CUSTOMSCREEN,
+    SA_Pens,        (ULONG)~0,  /* use 3D pen defaults */
+    SA_Font,        &topaz8,
+    TAG_DONE);
+```
+
+### Common SA_ Tags
+
+| Tag | Description |
+|---|---|
+| `SA_Width`, `SA_Height` | Screen dimensions |
+| `SA_Depth` | Bitplane count (1–8) |
+| `SA_DisplayID` | ModeID from display database |
+| `SA_Title` | Title bar text |
+| `SA_ShowTitle` | Show/hide title bar |
+| `SA_Type` | `CUSTOMSCREEN`, `PUBLICSCREEN` |
+| `SA_Behind` | Open behind other screens |
+| `SA_Quiet` | No title bar at all |
+| `SA_AutoScroll` | Allow autoscrolling |
+| `SA_Overscan` | Overscan type (`OSCAN_TEXT`, `OSCAN_STANDARD`, `OSCAN_MAX`) |
+| `SA_Pens` | DrawInfo pen array (3D look) |
+| `SA_Interleaved` | Use interleaved bitmap |
+| `SA_Colors32` | 32-bit colour palette |
+| `SA_PubName` | Public screen name |
+
+---
+
+## Closing
+
+```c
+CloseScreen(scr);
+/* All windows must be closed first! */
+```
+
+---
+
+## Public Screens
+
+```c
+/* Open a public screen: */
+struct Screen *pub = OpenScreenTags(NULL,
+    SA_Type,    PUBLICSCREEN,
+    SA_PubName, "MYAPP",
+    SA_Title,   "My Public Screen",
+    TAG_DONE);
+PubScreenStatus(pub, 0);  /* make it available */
+
+/* From another process, open a window on it: */
+struct Screen *found = LockPubScreen("MYAPP");
+struct Window *win = OpenWindowTags(NULL,
+    WA_PubScreen, found,
+    WA_Title, "On MYAPP",
+    TAG_DONE);
+UnlockPubScreen(NULL, found);
+```
+
+---
+
+## References
+
+- NDK39: `intuition/screens.h`, `intuition/intuition.h`
+- ADCD 2.1: `OpenScreenTagList`, `CloseScreen`, `LockPubScreen`