The Web-based Package Browser

Appnr

Appnr is a web-based tool and a service that install applications on Ubuntu. This is a web interface for APT, and the package is downloaded and installed from Ubuntu/Third-party repositories.

The AptURL Protocol Handler and a Web browser support are required to install applications. Please see Help page.


How to Download YouTube Video using Ubuntu Linux

Thereis a simple way to download YouTube video using Ubuntu Linux. But

firstly you need to install youtube-dl. Here’s how to do:

  1. Suppose your computer is now running Ubuntu Linux.
  2. Open terminal (click Applications > Accessories > Terminal)
  3. Type sudo apt-get install youtube-dl.
  4. Type in your linux password.
  5. Now you’re ready to go. To download your favorite video, simply type youtube-dl -t THE_URL_OF_YOUTUBE_VIDEO. The -t parameter will add video title into the file name.
  6. The downloaded file, which is saved in FLV format, then could be
    played using Media Player (in Linux), FLV player (in Windows), or
    another FLV player program.
  7. That’s it! Enjoy the videos :)


Debian GNU/Linux Installation Guide

Copyright © 2004, 2005, 2006, 2007 the Debian Installer team

This manual is free software; you may redistribute it and/or modify it under the terms of the GNU General Public License. Please refer to the license in Appendix F, GNU General Public License.

Abstract

This document contains installation instructions for the Debian GNU/Linux 4.0 system (codename “etch”), for the PowerPC (“powerpc”) architecture. It also contains pointers to more information and information on how to make the most of your new Debian system.

Warning

This installation guide is based on an earlier manual written for the old Debian installation system (the “boot-floppies”), and has been updated to document the new Debian installer. However, for powerpc, the manual has not been fully updated and fact checked for the new installer. There may remain parts of the manual that are incomplete or outdated or that still document the boot-floppies installer. A newer version of this manual, possibly better documenting this architecture, may be found on the Internet at the debian-installer home page. You may also be able to find additional translations there.


Table of Contents

Installing Debian GNU/Linux 4.0 For powerpc

1. Welcome to Debian

1.1. What is Debian?

1.2. What is GNU/Linux?

1.3. What is Debian GNU/Linux?

1.4. Getting Debian

1.5. Getting the Newest Version of This Document

1.6. Organization of This Document

1.7. About Copyrights and Software Licenses

2. System Requirements

2.1. Supported Hardware

2.1.1. Supported Architectures

2.1.2. CPU, Main Boards, and Video Support

2.1.3. Graphics Card Support

2.1.4. Multiple Processors

2.2. Installation Media

2.2.1. Floppies

2.2.2. CD-ROM/DVD-ROM

2.2.3. Hard Disk

2.2.4. USB Memory Stick

2.2.5. Network

2.2.6. Un*x or GNU system

2.2.7. Supported Storage Systems

2.3. Peripherals and Other Hardware

2.4. Purchasing Hardware Specifically for GNU/Linux

2.4.1. Avoid Proprietary or Closed Hardware

2.5. Memory and Disk Space Requirements

2.6. Network Connectivity Hardware

2.6.1. Drivers Requiring Firmware

2.6.2. Wireless Network Cards

3. Before Installing Debian GNU/Linux

3.1. Overview of the Installation Process

3.2. Back Up Your Existing Data!

3.3. Information You Will Need

3.3.1. Documentation

3.3.2. Finding Sources of Hardware Information

3.3.3. Hardware Compatibility

3.3.4. Network Settings

3.4. Meeting Minimum Hardware Requirements

3.5. Pre-Partitioning for Multi-Boot Systems

3.5.1. MacOS/OSX Partitioning

3.6. Pre-Installation Hardware and Operating System Setup

3.6.1. Invoking OpenFirmware

3.6.2. Hardware Issues to Watch Out For

4. Obtaining System Installation Media

4.1. Official Debian GNU/Linux CD-ROM Sets

4.2. Downloading Files from Debian Mirrors

4.2.1. Where to Find Installation Images

4.3. Creating Floppies from Disk Images

4.3.1. Writing Disk Images From a Linux or Unix System

4.3.2. Writing Disk Images From DOS, Windows, or OS/2

4.3.3. Writing Disk Images From MacOS

4.4. Preparing Files for USB Memory Stick Booting

4.4.1. Copying the files — the easy way

4.4.2. Copying the files — the flexible way

4.4.3. Adding an ISO image

4.5. Preparing Files for Hard Disk Booting

4.5.1. Hard Disk Installer Booting for OldWorld Macs

4.5.2. Hard Disk Installer Booting for NewWorld Macs

4.6. Preparing Files for TFTP Net Booting

4.6.1. Setting up a BOOTP server

4.6.2. Setting up a DHCP server

4.6.3. Enabling the TFTP Server

4.6.4. Move TFTP Images Into Place

4.7. Automatic Installation

4.7.1. Automatic Installation Using the Debian Installer

5. Booting the Installation System

5.1. Booting the Installer on PowerPC

5.1.1. Booting from a CD-ROM

5.1.2. Booting from Hard Disk

5.1.3. Booting from USB memory stick

5.1.4. Booting with TFTP

5.1.5. Booting from Floppies

5.1.6. PowerPC Boot Parameters

5.2. Boot Parameters

5.2.1. Debian Installer Parameters

5.3. Troubleshooting the Installation Process

5.3.1. CD-ROM Reliability

5.3.2. Floppy Disk Reliability

5.3.3. Boot Configuration

5.3.4. Interpreting the Kernel Startup Messages

5.3.5. Reporting Installation Problems

5.3.6. Submitting Installation Reports

6. Using the Debian Installer

6.1. How the Installer Works

6.2. Components Introduction

6.3. Using Individual Components

6.3.1. Setting up Debian Installer and Hardware Configuration

6.3.2. Partitioning and Mount Point Selection

6.3.3. Setting up the System

6.3.4. Installing the Base System

6.3.5. Installing Additional Software

6.3.6. Making Your System Bootable

6.3.7. Finishing the Installation

6.3.8. Miscellaneous

7. Booting Into Your New Debian System

7.1. The Moment of Truth

7.1.1. OldWorld PowerMacs

7.1.2. NewWorld PowerMacs

7.2. Mounting encrypted volumes

7.2.1. dm-crypt

7.2.2. loop-AES

7.2.3. Troubleshooting

7.3. Log In

8. Next Steps and Where to Go From Here

8.1. Shutting down the system

8.2. If You Are New to Unix

8.3. Orienting Yourself to Debian

8.3.1. Debian Packaging System

8.3.2. Application Version Management

8.3.3. Cron Job Management

8.4. Further Reading and Information

8.5. Setting Up Your System To Use E-Mail

8.5.1. Default E-Mail Configuration

8.5.2. Sending E-Mails Outside The System

8.5.3. Configuring the Exim4 Mail Transport Agent

8.6. Compiling a New Kernel

8.6.1. Kernel Image Management

8.7. Recovering a Broken System

A. Installation Howto

A.1. Preliminaries

A.2. Booting the installer

A.2.1. CDROM

A.2.2. Floppy

A.2.3. USB memory stick

A.2.4. Booting from network

A.2.5. Booting from hard disk

A.3. Installation

A.4. Send us an installation report

A.5. And finally…

B. Automating the installation using preseeding

B.1. Introduction

B.1.1. Preseeding methods

B.1.2. Limitations

B.2. Using preseeding

B.2.1. Loading the preconfiguration file

B.2.2. Using boot parameters to preseed questions

B.2.3. Auto mode

B.2.4. Aliases useful with preseeding

B.2.5. Using a DHCP server to specify preconfiguration files

B.3. Creating a preconfiguration file

B.4. Contents of the preconfiguration file

B.4.1. Localization

B.4.2. Network configuration

B.4.3. Mirror settings

B.4.4. Partitioning

B.4.5. Partitioning using RAID

B.4.6. Clock and time zone setup

B.4.7. Apt setup

B.4.8. Account setup

B.4.9. Base system installation

B.4.10. Boot loader installation

B.4.11. Package selection

B.4.12. Finishing up the first stage install

B.4.13. X configuration

B.4.14. Preseeding other packages

B.5. Advanced options

B.5.1. Running custom commands during the installation

B.5.2. Using preseeding to change default values

B.5.3. Chainloading preconfiguration files

C. Partitioning for Debian

C.1. Deciding on Debian Partitions and Sizes

C.2. The Directory Tree

C.3. Recommended Partitioning Scheme

C.4. Device Names in Linux

C.5. Debian Partitioning Programs

C.5.1. Partitioning Newer PowerMacs

D. Random Bits

D.1. Linux Devices

D.1.1. Setting Up Your Mouse

D.2. Disk Space Needed for Tasks

D.3. Installing Debian GNU/Linux from a Unix/Linux System

D.3.1. Getting Started

D.3.2. Install debootstrap

D.3.3. Run debootstrap

D.3.4. Configure The Base System

D.3.5. Install a Kernel

D.3.6. Set up the Boot Loader

D.3.7. Finishing touches

D.4. Installing Debian GNU/Linux using PPP over Ethernet (PPPoE)

D.5. The Graphical Installer

D.5.1. Using the graphical installer

D.5.2. Known issues

E. Administrivia

E.1. About This Document

E.2. Contributing to This Document

E.3. Major Contributions

E.4. Trademark Acknowledgement

F. GNU General Public License

List of Tables

3.1. Hardware Information Needed for an Install

3.2. Recommended Minimum System Requirements



2.2.2. CD-ROM/DVD-ROM

Note

Whenever you see “CD-ROM” in this manual, it applies to both CD-ROMs and DVD-ROMs, because both technologies are really the same from the operating system's point of view, except for some very old nonstandard CD-ROM drives which are neither SCSI nor IDE/ATAPI.

CD-ROM based installation is supported for some architectures. On machines which support bootable CD-ROMs, you should be able to do a completely floppy-less installation. Even if your system doesn't support booting from a CD-ROM, you can use the CD-ROM in conjunction with the other techniques to install your system, once you've booted up by other means; see Chapter 5, Booting the Installation System.

3.1. Overview of the Installation Process

First, just a note about re-installations. With Debian, a circumstance that will require a complete re-installation of your system is very rare; perhaps mechanical failure of the hard disk would be the most common case.

Many common operating systems may require a complete installation to be performed when critical failures take place or for upgrades to new OS versions. Even if a completely new installation isn't required, often the programs you use must be re-installed to operate properly in the new OS.

Under Debian GNU/Linux, it is much more likely that your OS can be repaired rather than replaced if things go wrong. Upgrades never require a wholesale installation; you can always upgrade in-place. And the programs are almost always compatible with successive OS releases. If a new program version requires newer supporting software, the Debian packaging system ensures that all the necessary software is automatically identified and installed. The point is, much effort has been put into avoiding the need for re-installation, so think of it as your very last option. The installer is not designed to re-install over an existing system.

Here's a road map for the steps you will take during the installation process.

1. Back up any existing data or documents on the hard disk where you plan to install.

2. Gather information about your computer and any needed documentation, before starting the installation.

3. Create partition-able space for Debian on your hard disk.

4. Locate and/or download the installer software and any specialized driver files your machine requires (except Debian CD users).

5. Set up boot tapes/floppies/USB sticks, or place boot files (most Debian CD users can boot from one of the CDs).

6. Boot the installation system.

7. Select the installation language.

8. Activate the ethernet network connection, if available.

9. Create and mount the partitions on which Debian will be installed.

10. Watch the automatic download/install/setup of the base system.

11. Install a boot loader which can start up Debian GNU/Linux and/or your existing system.

12. Load the newly installed system for the first time.

For PowerPC you have the option of using an experimental graphical version of the installation system. For more information about this graphical installer, see Section D.5, “The Graphical Installer”.

If you have problems during the installation, it helps to know which packages are involved in which steps. Introducing the leading software actors in this installation drama:

The installer software, debian-installer, is the primary concern of this manual. It detects hardware and loads appropriate drivers, uses dhcp-client to set up the network connection, runs debootstrap to install the base system packages, and runs tasksel to allow you to install certain additional software. Many more actors play smaller parts in this process, but debian-installer has completed its task when you load the new system for the first time.

To tune the system to your needs, tasksel allows you to choose to install various predefined bundles of software like a Web server or a Desktop environment.

One important option during the installation is whether or not to install a graphical desktop environment, consisting of the X Window System and one of the available graphical desktop environments. If you choose not to select the “Desktop environment” task, you will only have a relatively basic, command line driven system. Installing the Desktop environment task is optional because it requires a fairly large amount of disk space, and because many Debian GNU/Linux systems are servers which don't really have any need for a graphical user interface to do their job.

Just be aware that the X Window System is completely separate from debian-installer, and in fact is much more complicated. Installation and troubleshooting of the X Window System is not within the scope of this manual.

3.2. Back Up Your Existing Data!

Before you start, make sure to back up every file that is now on your system. If this is the first time a non-native operating system has been installed on your computer, it's quite likely you will need to re-partition your disk to make room for Debian GNU/Linux. Anytime you partition your disk, you run a risk of losing everything on the disk, no matter what program you use to do it. The programs used in installation are quite reliable and most have seen years of use; but they are also quite powerful and a false move can cost you. Even after backing up, be careful and think about your answers and actions. Two minutes of thinking can save hours of unnecessary work.

If you are creating a multi-boot system, make sure that you have the distribution media of any other present operating systems on hand. Especially if you repartition your boot drive, you might find that you have to reinstall your operating system's boot loader, or in many cases the whole operating system itself and all files on the affected partitions.

3.3. Information You Will Need

3.3.1. Documentation

3.3.1.1. Installation Manual

The document you are now reading, which is the official version of the Installation Guide for the etch release of Debian; available in various formats and translations.

3.3.1.2. Hardware documentation

Often contains useful information on configuring or using your hardware.

3.3.2. Finding Sources of Hardware Information

In many cases, the installer will be able to automatically detect your hardware. But to be prepared, we do recommend familiarizing yourself with your hardware before the install.

Hardware information can be gathered from:

· The manuals that come with each piece of hardware.

· The BIOS setup screens of your computer. You can view these screens when you start your computer by pressing a combination of keys. Check your manual for the combination. Often, it is the Delete key.

· The cases and boxes for each piece of hardware.

· System commands or tools in another operating system, including file manager displays. This source is especially useful for information about RAM and hard drive memory.

· Your system administrator or Internet Service Provider. These sources can tell you the settings you need to set up your networking and e-mail.

Table 3.1. Hardware Information Needed for an Install

Hardware

Information You Might Need

Hard Drives

How many you have.

Their order on the system.

Whether IDE or SCSI (most computers are IDE).

Available free space.

Partitions.

Partitions where other operating systems are installed.

Monitor

Model and manufacturer.

Resolutions supported.

Horizontal refresh rate.

Vertical refresh rate.

Color depth (number of colors) supported.

Screen size.

Mouse

Type: serial, PS/2, or USB.

Port.

Manufacturer.

Number of buttons.

Network

Model and manufacturer.

Type of adapter.

Printer

Model and manufacturer.

Printing resolutions supported.

Video Card

Model and manufacturer.

Video RAM available.

Resolutions and color depths supported (these should be checked against your monitor's capabilities).

3.3.3. Hardware Compatibility

Many brand name products work without trouble on Linux. Moreover, hardware support in Linux is improving daily. However, Linux still does not run as many different types of hardware as some operating systems.

You can check hardware compatibility by:

· Checking manufacturers' web sites for new drivers.

· Looking at web sites or manuals for information about emulation. Lesser known brands can sometimes use the drivers or settings for better-known ones.

· Checking hardware compatibility lists for Linux on web sites dedicated to your architecture.

· Searching the Internet for other users' experiences.

3.3.4. Network Settings

If your computer is connected to a network 24 hours a day (i.e., an Ethernet or equivalent connection — not a PPP connection), you should ask your network's system administrator for this information.

· Your host name (you may be able to decide this on your own).

· Your domain name.

· Your computer's IP address.

· The netmask to use with your network.

· The IP address of the default gateway system you should route to, if your network has a gateway.

· The system on your network that you should use as a DNS (Domain Name Service) server.

On the other hand, if your administrator tells you that a DHCP server is available and is recommended, then you don't need this information because the DHCP server will provide it directly to your computer during the installation process.

If you use a wireless network, you should also find out:

· ESSID of your wireless network.

· WEP security key (if applicable).

3.4. Meeting Minimum Hardware Requirements

Once you have gathered information about your computer's hardware, check that your hardware will let you do the type of installation that you want to do.

Depending on your needs, you might manage with less than some of the recommended hardware listed in the table below. However, most users risk being frustrated if they ignore these suggestions.

Any OldWorld or NewWorld PowerPC can serve well as a desktop system.

Table 3.2. Recommended Minimum System Requirements

Install Type

RAM (minimal)

RAM (recommended)

Hard Drive

No desktop

64 megabytes

256 megabytes

1 gigabyte

With Desktop

64 megabytes

512 megabytes

5 gigabyte

The actual minimum memory requirements are a lot less then the numbers listed in this table. Depending on the architecture, it is possible to install Debian with as little as 20MB (for s390) to 48MB (for i386 and amd64). The same goes for the disk space requirements, especially if you pick and choose which applications to install; see Section D.2, “Disk Space Needed for Tasks” for additional information on disk space requirements.

It is possible to run a graphical desktop environment on older or low-end systems, but in that case it is recommended to install a window manager that is less resource-hungry than those of the GNOME or KDE desktop environments; alternatives include xfce4, icewm and wmaker, but there are others to choose from.

It is practically impossible to give general memory or disk space requirements for server installations as those very much depend on what the server is to be used for.

Remember that these sizes don't include all the other materials which are usually to be found, such as user files, mail, and data. It is always best to be generous when considering the space for your own files and data.

Disk space required for the smooth operation of the Debian GNU/Linux system itself is taken into account in these recommended system requirements. Notably, the /var partition contains a lot of state information specific to Debian in addition to its regular contents, like logfiles. The dpkg files (with information on all installed packages) can easily consume 40MB. Also, apt-get puts downloaded packages here before they are installed. You should usually allocate at least 200MB for /var, and a lot more if you install a graphical desktop environment.

3.5. Pre-Partitioning for Multi-Boot Systems

Partitioning your disk simply refers to the act of breaking up your disk into sections. Each section is then independent of the others. It's roughly equivalent to putting up walls inside a house; if you add furniture to one room it doesn't affect any other room.

If you already have an operating system on your system and want to stick Linux on the same disk, you will need to repartition the disk. Debian requires its own hard disk partitions. It cannot be installed on Windows or MacOS partitions. It may be able to share some partitions with other Linux systems, but that's not covered here. At the very least you will need a dedicated partition for the Debian root.

You can find information about your current partition setup by using a partitioning tool for your current operating system, such as Drive Setup, HD Toolkit, or MacTools. Partitioning tools always provide a way to show existing partitions without making changes.

In general, changing a partition with a file system already on it will destroy any information there. Thus you should always make backups before doing any repartitioning. Using the analogy of the house, you would probably want to move all the furniture out of the way before moving a wall or you risk destroying it.

If your computer has more than one hard disk, you may want to dedicate one of the hard disks completely to Debian. If so, you don't need to partition that disk before booting the installation system; the installer's included partitioning program can handle the job nicely.

If your machine has only one hard disk, and you would like to completely replace the current operating system with Debian GNU/Linux, you also can wait to partition as part of the installation process (Section 6.3.2.1, “Partitioning Your Disks”), after you have booted the installation system. However this only works if you plan to boot the installer system from tapes, CD-ROM or files on a connected machine. Consider: if you boot from files placed on the hard disk, and then partition that same hard disk within the installation system, thus erasing the boot files, you'd better hope the installation is successful the first time around. At the least in this case, you should have some alternate means of reviving your machine like the original system's installation tapes or CDs.

If your machine already has multiple partitions, and enough space can be provided by deleting and replacing one or more of them, then you too can wait and use the Debian installer's partitioning program. You should still read through the material below, because there may be special circumstances like the order of the existing partitions within the partition map, that force you to partition before installing anyway.

If none of the above apply, you'll need to partition your hard disk before starting the installation to create partition-able space for Debian. If some of the partitions will be owned by other operating systems, you should create those partitions using native operating system partitioning programs. We recommend that you do not attempt to create partitions for Debian GNU/Linux using another operating system's tools. Instead, you should just create the native operating system's partitions you will want to retain.

If you are going to install more than one operating system on the same machine, you should install all other system(s) before proceeding with Linux installation. Windows and other OS installations may destroy your ability to start Linux, or encourage you to reformat non-native partitions.

You can recover from these actions or avoid them, but installing the native system first saves you trouble.

In order for OpenFirmware to automatically boot Debian GNU/Linux the Linux partitions should appear before all other partitions on the disk, especially MacOS boot partitions. This should be kept in mind when pre-partitioning; you should create a Linux placeholder partition to come before the other bootable partitions on the disk. (The small partitions dedicated to Apple disk drivers are not bootable.) You can delete the placeholder with the Linux partition tools later during the actual install, and replace it with Linux partitions.

If you currently have one hard disk with one partition (a common setup for desktop computers), and you want to multi-boot the native operating system and Debian, you will need to:

1. Back up everything on the computer.

2. Boot from the native operating system installer media such as CD-ROM or tapes. When booting from a MacOS CD, hold the c key while booting to force the CD to become the active MacOS system.

3. Use the native partitioning tools to create native system partition(s). Leave either a place holder partition or free space for Debian GNU/Linux.

4. Install the native operating system on its new partition.

5. Boot back into the native system to verify everything's OK, and to download the Debian installer boot files.

6. Boot the Debian installer to continue installing Debian.

3.5.1. MacOS/OSX Partitioning

The Apple Drive Setup application can be found in the Utilities folder on the MacOS CD. It will not adjust existing partitions; it is limited to partitioning the entire disk at once. The disk driver partitions don't show up in Drive Setup.

Remember to create a placeholder partition for GNU/Linux, preferably positioned first in the disk layout. it doesn't matter what type it is, it will be deleted and replaced later inside the Debian GNU/Linux installer.

If you are planning to install both MacOS 9 and OS X, it is best to create separate partitions for OS 9 and OS X. If they are installed on the same partition, Startup Disk (and reboot) must be used to select between the two; the choice between the two systems can't be made at boot time. With separate partitions, separate options for OS 9 and OS X will appear when holding the option key at boot time, and separate options can be installed in the yaboot boot menu as well. Also, Startup Disk will de-bless all other mountable partitions, which can affect GNU/Linux booting. Both OS 9 and OS X partitions will be accessible from either OS 9 or OS X.

GNU/Linux is unable to access information on UFS partitions, but does support HFS+ (aka MacOS Extended) partitions. OS X requires one of these two types for its boot partition. MacOS 9 can be installed on either HFS (aka MacOS Standard) or HFS+. To share information between the MacOS and GNU/Linux systems, an exchange partition is handy. HFS, HFS+ and MS-DOS FAT partitions are supported by both MacOS and Linux.

3.6. Pre-Installation Hardware and Operating System Setup

This section will walk you through pre-installation hardware setup, if any, that you will need to do prior to installing Debian. Generally, this involves checking and possibly changing firmware settings for your system. The “firmware” is the core software used by the hardware; it is most critically invoked during the bootstrap process (after power-up). Known hardware issues affecting the reliability of Debian GNU/Linux on your system are also highlighted.

3.6.1. Invoking OpenFirmware

There is normally no need to set up the BIOS (called OpenFirmware) on PowerPC systems. PReP and CHRP are equipped with OpenFirmware, but unfortunately, the means you use to invoke it vary from manufacturer to manufacturer. You'll have to consult the hardware documentation which came with your machine.

On PowerPC Macintoshes, you invoke OpenFirmware with Command-option-O-F while booting. Generally it will check for these keystrokes after the chime, but the exact timing varies from model to model. See http://www.netbsd.org/Ports/macppc/faq.html for more hints.

The OpenFirmware prompt looks like this:

ok
0 >

Note that on older model PowerPC Macs, the default and sometimes hardwired I/O for OpenFirmware user interaction is through the serial (modem) port. If you invoke OpenFirmware on one of these machines, you will just see a black screen. In that case, a terminal program running on another computer, connected to the modem port, is needed to interact with OpenFirmware.

The OpenFirmware on OldWorld Beige G3 machines, OF versions 2.0f1 and 2.4, is broken. These machines will most likely not be able to boot from the hard drive unless the firmware is patched. A firmware patch is included in the System Disk 2.3.1 utility, available from Apple at ftp://ftp.apple.com/developer/macosxserver/utilities/SystemDisk2.3.1.smi.bin. After unpacking the utility in MacOS, and launching it, select the Save button to have the firmware patches installed to nvram.

3.6.2. Hardware Issues to Watch Out For

Display-visibility on OldWorld Powermacs. Some OldWorld Powermacs, most notably those with the “control” display driver, may not reliably produce a colormap under Linux when the display is configured for more than 256 colors. If you are experiencing such issues with your display after rebooting (you can sometimes see data on the monitor, but on other occasions cannot see anything) or, if the screen turns black after booting the installer instead of showing you the user interface, try changing your display settings under MacOS to use 256 colors instead of “thousands” or “millions”.