The Raspberry Pi is a small credit card sized computer that runs its operating system from an SD Card.One of the reasons it was developed was to teach children computer science and programming.It's also popular amongst hobbyists. http://raspberrypi.org
Download mainstream ones from http://www.raspberrypi.org/downloads
A list of distributions can be found at http://elinux.org/RPi_Distributions
Instructions are here http://elinux.org/RPi_Easy_SD_Card_Setup
Edit the boot config.txt file
sudo nano /boot/config.txtFind the Framebuffer_width and Framebuffer_height
Assuming the Pi is plugged into an 16:9 widescreen Hdmi TV find the appropriate resolution from hereChange the values in the file (Remove the # comment character if exists) eg:
Framebuffer_width=1024 Framebuffer_height=576Save the file and reboot
See details for the config.txt file at https://www.raspberrypi.org/documentation/configuration/config-txt.md
Setting for my own small monitor are:
overscan_left=30
overscan_right=30
overscan_top=26
overscan_bottom=26
hdmi_group=2
hdmi_mode=17
hdmi_drive=2
https://www.raspberrypi.org/forums/viewtopic.php?p=108862
Add your own custom images
$ sudo kpartx -av image_you_want_to_convert.img
add map loop0p1 (252:5): 0 117187 linear /dev/loop0 1
add map loop0p2 (252:6): 0 3493888 linear /dev/loop0 118784
$ sudo mount /dev/mapper/loop0p2 /mnt
$ sudo sed -i 's/^\/dev\/mmcblk/#\0/g' /mnt/etc/fstab
$ sudo sed -i 's/^PARTUUID/#\0/g' /mnt/etc/fstab
$ sudo rm -f /mnt/etc/console-setup/cached_UTF-8_del.kmap.gz
$ sudo rm -f /mnt/etc/systemd/system/multi-user.target.wants/apply_noobs_os_config.service
$ sudo rm -f /mnt/etc/systemd/system/multi-user.target.wants/raspberrypi-net-mods.service
$ sudo rm -f /mnt/etc/rc3.d/S01resize2fs_once
$ sudo mksquashfs /mnt converted_image_for_berryboot.img -comp lzo -e lib/modules
$ sudo umount /mnt
$ sudo kpartx -d image_you_want_to_convert.img