How to install Debian Buster on an aging (2008) ALIX2D13. A 500MHz single x86 CPU, 256MB memory board. These steps are based on a Ubuntu 18.04 LTS host.

• Get the board out of the case, for access to the CF card.
• Connect a serial console, power up and boot the board.
• Enter the BIOS settings, by pressing 's'.
• Set the console baud rate to 115200.
• Exit and save the settings.

• Remove the card out of the board, and connect it to your host machine.
• Partition the CF card:

  # Make sure you've got the the right blockdevice here.
  CFDRIVE=/dev/sdc
  
  # Unmount partitions if they are automounted.
  umount ${CFDRIVE}{1,2}
  
  # Remove partition table
  dd if=/dev/zero of=${CFDRIVE} bs=512 count=1 conv=notrunc
  
  # Make a new partion table for /boot and the / root filesystem.
  parted --script $CFDRIVE              \
      mklabel msdos                     \
      unit mib                          \
      mkpart primary ext4 1MiB 500MiB   \
      toggle 1 boot                     \
      mkpart primary ext4 500MiB 100%
  
  # Create the filesystems
  mkfs.ext4 -L boot ${CFDRIVE}1
  mkfs.ext4 -L root ${CFDRIVE}2
  
  # Mount the filesystems
  mount ${CFDRIVE}2 /mnt
  mkdir /mnt/boot
  mount ${CFDRIVE}1 /mnt/boot

• Install Debian Buster with debootstrap:

  debootstrap --verbose --arch i386 buster /mnt http://ftp.nl.debian.org/debian

• Bind mount some special filesystems and enter the chroot:

  mount --bind /dev/pts /mnt/dev/pts
  mount --bind /proc /mnt/proc
  mount --bind /sys /mnt/sys
  mount --bind /dev /mnt/dev
  
  LANG=C linux32 chroot /mnt /bin/bash

• Still in the chroot:

  # Configure /etc/fstab
  cat > /etc/fstab <<EOF
  # file system    mount point   type    options                      dump pass
  /dev/sda2         /             ext4    noatime,noatime,commit=120   0    1
  /dev/sda1         /boot         ext4    ro,nosuid,nodev              0    2
  EOF
  
  # Configure apt
  cat > /etc/apt/sources.list <<EOF
  deb http://ftp.nl.debian.org/debian buster main contrib non-free
  #deb-src http://ftp.nl.debian.org/debian buster main contrib non-free
  
  deb http://ftp.nl.debian.org/debian buster-updates main contrib non-free
  #deb-src http://ftp.nl.debian.org/debian buster-updates main contrib non-free
  
  deb http://security.debian.org/ buster/updates main contrib non-free
  #deb-src http://security.debian.org/ buster/updates main contrib non-free
  EOF
  
  # Update the packages
  apt update
  apt upgrade
  
  # Install needed packages
  apt install linux-image-686 grub-pc dnsutils ssh vim dialog locales 
  
  # Install grub, change the blockdevice to your own
  grub-install --boot-directory=/boot --modules=part_msdos /dev/sd?
  
  # Modify GRUB settings (for serial console) in /etc/default/grub
  GRUB_CMDLINE_LINUX_DEFAULT=""
  GRUB_CMDLINE_LINUX="console=tty0 console=ttyS0,115200n8"
  GRUB_TERMINAL=serial
  GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"
  
  # Generate a new GRUB config
  grub-mkconfig -o /boot/grub/grub.cfg
  
  # Add user and set passwords for user and root
  useradd -d /home/user -m -s /bin/bash user
  passwd user
  passwd root
  
  # Set hostname
  echo alix2d13 > /etc/hostname
  echo "127.0.0.1 alix2d13" >>/etc/hosts
  
  # Configure the first network interface (as DHCP client)
  cat > /etc/systemd/network/enp0s9.network <<EOF
  [Match]
  Name=enp0s9
  
  [Network]
  DHCP=ipv4
  EOF
  
  # Exit the chroot and unmount filesystems
  exit
  umount /mnt/sys
  umount /mnt/dev
  umount /mnt/dev/pts
  umount /mnt/proc
  umount /mnt/boot
  umount /mnt
  sync

• Insert the CF card in the board and power it up.
• Log in as root and enable networking:

  systemctl start systemd-resolved
  systemctl enable systemd-resolved
  
  systemctl start systemd-networkd
  systemctl enable systemd-networkd

• Set the timezone:

  timedatectl set-timezone Europe/Amsterdam

• Configure locales

  dpkg-reconfigure locales

The LED's are supported out of the box.

• Install sysfsutils:

  apt install sysfsutils

• Add to /etc/sysfs.conf:

  devices/platform/leds-gpio/leds/alix:1/brightness = 1
  devices/platform/leds-gpio/leds/alix:2/trigger = disk-activity

• Restart sysfsutils (or reboot) to test:

  systemctl restart sysfsutils