Physical Address Extension (PAE) is a feature to allow (32-bit) x86 processors to access a physical address space (including random access memory and memory mapped devices) larger than 4 gigabytes.

Ubuntu 12.04 (as well as Kubuntu 12.04) uses the PAE Linux kernel by default for 32bit ISOs so old computers that don't support PAE can't boot the latest Ubuntu version. But there is a way to install Ubuntu 12.04 LTS Precise Pangolin on computers without PAE support: using the non-PAE netboot Minimal ISO (there are also some alternatives, see below).

The non-PAE netboot mini ISO lets you install the non-PAE kernel and the desktop environment you want: you can select to install Ubuntu Desktop (with Unity), Kubuntu Desktop and so on. One note though: since the minimal CD will download packages from online archives at installation time instead of providing them on the install CD itself, you need a working Internet connection during the installation.

Install Ubuntu 12.04 LTS on non-PAE capable systems using the netboot minimal ISO

Download mini.iso from HERE, write it on a CD or USB stick and boot from the ISO like with the regular Ubuntu ISO and select "Install":

The installer will now ask you a bunch of questions regarding the keyboard, etc. - select the options you want (use TAB to move through fields, SPACE to select and ENTER to activate buttons / continue). If you use a proxy, you'll be asked to enter it before the installation starts:

Basically, all the info available in the regular installer are also available for the mini ISO, like selecting your country, choose if you want to encrypt you home directory, partition the hard disk and so on:

After partitioning your hard disk, the installer will start downloading the core packages:

If some packages fail to download, you can select to continue and at the end of this step, you'll get to the Ubuntu Installer Main Menu where you can select "Install the base system" so the installer will try to redownload the packages for which the download failed:

Next, you'll be asked to select the Linux kernel you want to use - here, select "linux-generic":

The next important step is to select the desktop environment you want to use. Select it using the SPACE key (don't just press enter or else you'll end up with the core system only and without a graphical desktop environment!):

• for Unity, select "Ubuntu Desktop"
• for KDE / Kubuntu, select "Kubuntu Desktop"

Next, make sure you install the GRUB bootloader (by simply selecting "Yes" when you reach the screen below):

And that's about it, after you complete the above steps, you should have a working Ubuntu 12.04 LTS (with Unity or KDE) that runs on non-PAE supported hardware.

You can also watch a video with the whole non-PAE Mini ISO Ubuntu 12.04 installation process, below:

(Direct video link)

Alternatives

Like I was telling you above, using the non-PAE mini ISO isn't the only way to install Ubuntu 12.04 Precise Pangolin on computers that don't support PAE. You can also install Xubuntu or Lubuntu since both come with non-PAE Linux kernels, and if you don't want to use XFCE or LXDE, simply open a terminal and type:

- for Unity (and all the default Ubuntu packages):

sudo apt-get install ubuntu-desktop

- for KDE:

sudo apt-get install kubuntu-desktop

¿Nuevo en Linux o deseas cambiar de distro, y no sabes a cuál? Da clic en la siguiente imagen para ver una excelente guía que te ayudará a elegir la distro perfecta para ti

Vía: Gabuntu.

Cuento brevemente mi historia. Cuando compré mi portátil, todo funcionaba a la perfección en Linux, era algo raro, pero lo hice a posta, me dediqué a estudiar las especificaciones hasta estar seguro de que todos los dispositivos funcionarían.

Con la evolución de ubuntu (mejor dicho, del kernel….supongo) las cosas han ido a peor, el bluetooth no va todo lo bien que debería, y la wifi tiene mucho menos alcance, por no hablar de touchpad, que da tantos saltos que tengo que usar un ratón.

Por tanto he decido hacer un downgrade del kernel para ver si resuelve algo mi lastimosa situación….y es que si algo funciona…es ilógico que en versiones posteriores deje de hacerlo, a mi no me cabe en la cabeza y aprovecho para lanzar una crítica constructiva al kernel y sus desarrolladores. Todo tiene que ser más transparente para el usuario medio.

Bueno, vamos al lío. Para hacer un downgrade del kernel haremos lo siguiente:

Nos dirigimos a http://packages.ubuntu.com/

Buscamos el kernel que “más nos guste” en la sección:

/versión_ubuntu-update/linux-image

- Por ejemplo en – http://packages.ubuntu.com/natty-updates/linux-image

Lo descargamos y con un terminal instalamos con el comando:

sudo dpkg -i linux-image-versión.deb

If you need to change the computer name (hostname) in Ubuntu for whatever reason, you won't find a System Settings option to do it so you must edit two configuration files. But don't worry, it's an easy task!

How to change the hostname (computer name) in Ubuntu

To change the hostname in Ubuntu, you must edit 2 files. So open a terminal and run the following commands:

1. Optional: make a backup of your existing 'hostname' and 'hosts' files (it's a good idea because if you don't change the hostname properly, you might get some gksu / sudo issues):

sudo cp /etc/hosts /etc/hosts.old
sudo cp /etc/hostname /etc/hostname.old

2. Edit the 'hosts' file:

gksu gedit /etc/hosts

The file should look like this:

127.0.0.1       localhost
127.0.1.1       some_hostname

Here, change "some_hostname" to the new hostname / computer name.

3. Edit the hostname file:

gksu gedit /etc/hostname

This file only contains your hostname so change it again to what you like, but make sure it's the same as in the hostname in the /etc/hosts file.

4. Now restart the hostname and networking services:

sudo service hostname restart
sudo service networking restart

Your new computer name / hostname should now show up instead of the old one. After this, log out and log back in to avoid some issues like "gksu" not working.

Instead of the last two commands above, you can also simply restart your computer.

Reverting the changes

Since we've made a backup, reverting the changes is easy: all you have to do is copy the backup files and replace the new ones:

sudo cp /etc/hosts.old /etc/hosts
sudo cp /etc/hostname.old /etc/hostname

In case you're having issues with "sudo", use "gksu" instead.