If you’re like me you attend to go back and forth with Operating Systems. When this happens you have different boot loaders for the different OS/s. Windows uses the Microsoft Boot loader and Linux uses Grub or Lilo. I hate having to switch back and forth so I found a very nice alternative. The alternative is a different bootloader is flashed into a Option ROM and then called when the BIOS runs the INT 19h/INT 18h interrupt call. I’m layman’s terms finds the closest boot code. Or for the end user tricks the system to think it’s loading BASIC or the BIOS front end. The Boot loader I am talking about is called the Plop Boot Manager. I really like this not only because of the option to have it load from a Option ROM but you can boot legacy systems that do not have a bootable USB option or use the bootloader from a PXE environment.
Now how can you add this Option ROM. Well every device in a PC uses a Option ROM device but are in use except one device that is mostly over looked. A Ethernet card will have a empty IC socket. This empty IC socket when populated is used for booting a OS over a network. Mostly used for PXE or what have you. You can flash a chip that holds the bootloader and have it in the card. Some PNP BIOS systems will have a option to set the LAN as a bootable device. Older systems will need a bootable image and will use the INT 19h/INT 18h interrupt.
This doesn’t mean it will work with any Ethernet card. You can’t use integrated Ethernet that is built into a motherboard since the built in Option ROM coincides with the system BIOS. It has to be a add in card and only a few can be used with out a IC programmer. For a example of a prime card of choice is the Intel 10/100 Pro. They have a PLC type socket and again if you’re like me and when you tear down broken motherboards you keep the old BIOS chips if they’re removable. Now it doesn’t mean you have to use this card for Ethernet use. You can ignore it, disable it in Device Manager or skip the drivers. There are also a few ways to flash it. Some people have had success using a BIOS flash tool from AMI. I myself prefer to use a Linux environment and a program called FlashROM. You can also use a version for DOS but your mileage will very. I prefer Linux because I can get the exact hardware ID and Address so I don’t end up writing to my GPU or BIOS.
In all you can write crap all over the MBR on the hard drive and still be able to boot the system.