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boot_sequence: enrich all articles + new kickstart_rom.md

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New: kickstart_rom.md (ROM structure, module inventory, tools, custom ROMs)
Enriched: cold_boot (diagnostics, LED codes, troubleshooting),
kickstart_init (ExecBase creation, ROM scan, 4-phase init),
dos_boot (strap, boot block, Startup-Sequence), early_startup (recovery)
Updated: 02_boot_sequence/README.md, root README.md
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02_boot_sequence/early_startup.md
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[← Home](../README.md) · [Boot Sequence](README.md)
# Early Startup Control — Boot Options
# Early Startup Control — Boot Menu, Display Mode, Recovery
## 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.
The **Early Startup Control** (ESC) menu is a built-in boot manager available on all Amigas with Kickstart 2.0+. It provides boot device selection, display mode override, and emergency recovery options. It appears when both mouse buttons are held during the early boot phase — before the OS loads from disk.
---
## 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)
### How to Trigger
Hold **both mouse buttons** (left + right) immediately after power-on or during the Ctrl-Amiga-Amiga reset sequence. The timing window is:
| Kickstart | When to Hold | Visual Cue |
|---|---|---|
| 2.0–3.0 | During boot colour sequence | Before "Insert Disk" or disk activity |
| 3.1 | During the hand/checkmark animation | While the Amiga hand appears |
| 3.1.4 / 3.2 | Same as 3.1 | Same timing window |
> **Tip**: Hold both buttons before powering on — this guarantees you catch the window. Release them once the menu appears.
### Not Available On
- Kickstart 1.2 / 1.3 (no boot menu feature)
- Any system where the ROM is corrupted (red screen before menu)
- Systems with custom boot ROMs that bypass standard init
---
## Menu Options (OS 3.1)
## Menu Layout
### OS 3.1 Early Startup Control
```
┌──────────────────────────────────┐
│ EARLY STARTUP CONTROL │
│ │
│ Boot With No Startup-Sequence │
│ Boot Standard │
│ │
│ Boot Device: │
│ DF0: (pri 5) │
│ DH0: (pri 0) │
│ │
│ Display Mode: │
│ ● PAL ○ NTSC │
│ │
│ [BOOT] │
└──────────────────────────────────┘
╔══════════════════════════════════════════╗
║ EARLY STARTUP CONTROL ║
║ ║
║ Boot Options: ║
║ ○ Boot With No Startup-Sequence ║
║ ● Boot Standard ║
║ ║
║ Boot Device: ║
║ ● DF0: (pri 5) ║
║ ○ DH0: (pri 0) ║
║ ○ DH1: (pri -5) ║
║ ║
║ Display Mode: ║
║ ● PAL ○ NTSC ║
║ ║
║ [ BOOT ] ║
╚══════════════════════════════════════════╝
```
### OS 3.2 Early Startup Control
OS 3.2 adds additional options:
```
╔══════════════════════════════════════════╗
║ EARLY STARTUP CONTROL ║
║ ║
║ Boot Options: ║
║ ○ Boot With No Startup-Sequence ║
║ ● Boot Standard ║
║ ○ Boot (Debug) ║
║ ║
║ Boot Device: ║
║ ● DF0: (pri 5) ║
║ ○ DH0: (pri 0) "System3.1" ║
║ ○ DH1: (pri -5) "Work" ║
║ ○ CD0: (pri -20) ║
║ ║
║ Display Mode: ║
║ ○ PAL ○ NTSC ● Best Available ║
║ ║
║ ROM Modules: ║
║ [x] Enable SetPatch ║
║ [x] Enable 68040.library ║
║ ║
║ [ BOOT ] ║
╚══════════════════════════════════════════╝
```
---
## Menu Options
### Boot Options
| Option | Effect |
|---|---|
| **Boot Standard** | Normal boot — executes S:Startup-Sequence |
| **Boot With No Startup-Sequence** | Boots to a CLI prompt. S:Startup-Sequence is NOT executed. Assigns (SYS:, C:, etc.) are still set. |
| **Boot (Debug)** | (OS 3.2) Boots with debugging enabled — serial debug output, extended logging |
### Boot Device Selection
Lists all devices registered with `AddBootNode()`:
- Floppy drives: DF0:, DF1: (always present if trackdisk.device loaded)
- Hard disk partitions: DH0:, DH1:, etc. (from RDB on SCSI/IDE)
- CD-ROM: CD0: (if device driver available)
- Network: (if SANA-II device registered as bootable)
Select a device and click BOOT — the system uses that device as `SYS:` regardless of configured boot priority.
### Display Mode
| Option | Effect |
|---|---|
| **PAL** | Force PAL display (50 Hz, 283 visible lines) |
| **NTSC** | Force NTSC display (60 Hz, 241 visible lines) |
| **Best Available** | (OS 3.2) Auto-detect from hardware and monitor |
> **Why this matters**: If someone changes the display mode to a setting their monitor can't sync to (e.g., PAL on an NTSC-only monitor), the screen goes blank. The ESC menu renders using the most basic display mode, so it's always visible — even when the configured mode is incompatible.
---
## How It Works Internally
### Detection
```c
/* During boot, before strap runs: */
/* intuition.library checks both mouse buttons via CIA-A/B port registers */
UBYTE ciaA_pra = ciaa.ciapra; /* CIA-A Port A — mouse button 1 (bit 6) */
UBYTE potgor = custom.potgor; /* POT port — mouse button 2 (bit 10) */
BOOL leftButton = !(ciaA_pra & 0x40); /* Active low */
BOOL rightButton = !(potgor & 0x0400); /* Active low */
if (leftButton && rightButton)
{
/* Both buttons held — enter Early Startup Control */
ShowBootMenu();
}
```
### Display
The ESC menu uses the lowest-level graphics possible:
- Opens a 640×200 (or 640×256 PAL) 2-colour screen
- Uses the Topaz 8 ROM font (always available — no disk access needed)
- Renders using direct `RastPort` calls — no windows, no layers
- Mouse pointer uses hardware sprite 0
### Boot Menu Rendering Order
1. `graphics.library` init completes → display hardware ready
2. `intuition.library` init completes → input handling ready
3. Check mouse buttons
4. If held: create the boot menu screen
5. Wait for user selection + BOOT button
6. Close screen, continue boot with selected options
---
## 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 |
### Corrupted Startup-Sequence
```
Problem: System hangs during boot — bad script
Fix:
1. Hold both mouse buttons → ESC menu
2. Select "Boot With No Startup-Sequence"
3. Boot → CLI prompt appears
4. Edit the script: ED S:Startup-Sequence
5. Reboot normally
```
### Wrong Display Mode (No Picture)
```
Problem: Changed to PAL on NTSC monitor (or vice versa) — screen blank
Fix:
1. Power off
2. Hold both mouse buttons, power on
3. ESC menu appears (uses safe display mode)
4. Select correct display mode (PAL/NTSC)
5. Click BOOT
```
### Boot from Floppy Instead of Hard Disk
```
Problem: Hard disk is corrupted, need to boot from floppy
Fix:
1. Insert bootable Workbench floppy in DF0:
2. Hold both mouse buttons during boot
3. Select DF0: as boot device
4. Click BOOT
5. System boots from floppy — hard disk accessible as DH0:
```
### Assign Loops / Infinite Requester
```
Problem: Startup-Sequence has an Assign to a missing volume
→ "Please insert volume X" in infinite loop
Fix:
1. ESC menu → "Boot With No Startup-Sequence"
2. Fix the Assign in S:Startup-Sequence
3. Or: Add NOREQ flag to the problematic Assign
Assign >NIL: WORK: DH1:
```
### Hard Disk Not Appearing in Boot Menu
```
Problem: DH0: doesn't show in the ESC boot device list
Possible causes:
1. IDE/SCSI device not detected — check cables
2. No valid RDB (Rigid Disk Block) — use HDToolBox
3. Boot priority not set — use HDToolBox to set BootPri
4. Partition table corrupt — try mounting from floppy boot
```
### Testing Multiple OS Versions
```
Scenario: Two OS versions on different partitions
1. Install OS 3.1 on DH0: (BootPri 0)
2. Install OS 3.2 on DH1: (BootPri -5)
3. Normal boot → DH0: (OS 3.1)
4. ESC menu → select DH1: → boots OS 3.2
5. Or: change BootPri in HDToolBox to swap default
```
---
## Keyboard Alternative
On Amiga 1000 (no right mouse button connector) or when mouse is unavailable:
- Some A1000 models use a key combination instead of mouse buttons
- External button boxes connected to the joystick port can substitute
- DiagROM provides keyboard-driven boot menu alternatives
---
@ -53,3 +248,6 @@ The **Early Startup Control** (ESC) menu appears when both mouse buttons are hel
- RKRM: Early Startup chapter
- OS 3.1 AmigaGuide: `System/BootMenu`
- OS 3.2 Release Notes: new ESC menu options
- See also: [DOS Boot](dos_boot.md) — what happens after device selection
- See also: [Cold Boot](cold_boot.md) — hardware init before ESC menu