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