CHR_VERSION=7.16.2
INSTALLPATH=/dev/vda
apt-get update &&
apt-get install -y unzip wget pv coreutils &&
wget https://download.mikrotik.com/routeros/${CHR_VERSION}/chr-${CHR_VERSION}.img.zip &&
unzip chr-${CHR_VERSION}.img.zip &&
echo 1 > /proc/sys/kernel/sysrq &&
(Serial port or com port? - Serial ports are often refered as COM ports. It is the same to be short. You can read abut it in the Wiki article )