Installing

Install for legacy boot

When you power on your computer you see BIOS which want to start some operating system. Old computers (legacy computers) have legacy BIOS which is able to boot some drive HDD, CDROM or USB-HDD. The BIOS read first sector (MBR) from the physical drive into memory and start is as a program written in 16bit codes. The program is less then 512 byte. It named boot0 boot sector. The program boot0 searches the partition table of the drive, finds first partition position (PBR) on the drive and reads there first one or two sectors named boot1. Start the program. The program PBR intended to use on the specific file-system. So use boot1hfs on HFS+ filesystem, use boot1f32 on FAT32 filesystem, boot1ex on exFAT file system and more. After years of investigations we decided to choose one case: drive must be formatted to GPT and have first partition EFI formatted to FAT32. Partition signature will be EF00. We have several variants but recommended one is boot0af It can be installed from macOS by command

sudo fdisk440 -f boot0 -u -y /dev/rdisk0

or by

dd if=/dev/rdisk0 count=1 bs=512 of=origMBR

cp origMBR newMBR

dd if=boot0 of=newMBR bs=1 count=440 conv=notrunc

dd if=newMBR of=/dev/rdisk0 count=1 bs=512

But the disk should not be system as macOS protect system disk from modifications.

Sector PBR must be updated by commands

dd if=/dev/rdisk0s1 count=1 bs=512 of=origbs

cp boot1f32alt newbs

dd if=origbs of=newbs skip=3 seek=3 bs=1 count=87 conv=notrunc

dd if=newbs of=/dev/rdisk0s1 count=1 bs=512