amiga-bootcamp/02_boot_sequence/early_startup.md
Ilia Sharin 21751c0025 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

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2026-04-23 12:17:35 -04:00

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[← Home](../README.md) · [Boot Sequence](README.md)
# Early Startup Control — Boot Options
## Overview
The **Early Startup Control** (ESC) menu appears when both mouse buttons are held during power-on or reset. It provides boot device selection, display mode override, and emergency recovery options.
---
## Activation
- **Both mouse buttons held** before the boot screen hand animation completes
- On A1200: hold both buttons during "floppy click" phase
- Requires Kickstart 2.0+ (not available on 1.3)
---
## Menu Options (OS 3.1)
```
┌──────────────────────────────────┐
│ EARLY STARTUP CONTROL │
│ │
│ Boot With No Startup-Sequence │
│ Boot Standard │
│ │
│ Boot Device: │
│ DF0: (pri 5) │
│ DH0: (pri 0) │
│ │
│ Display Mode: │
│ ● PAL ○ NTSC │
│ │
│ [BOOT] │
└──────────────────────────────────┘
```
---
## Recovery Scenarios
| Scenario | Fix |
|---|---|
| Corrupted Startup-Sequence | Boot with No Startup-Sequence, then `ED S:Startup-Sequence` |
| Wrong display mode (no image) | Hold both buttons → change PAL/NTSC |
| Boot from floppy instead of HD | Select DF0: as boot device |
| Assign loops / infinite boot | No Startup-Sequence → fix assigns manually |
---
## References
- RKRM: Early Startup chapter
- OS 3.1 AmigaGuide: `System/BootMenu`