possible to simulate a Boot Rom through DOS or a boot loader?
I am wondering if it would be possible to simulate a boot rom through DOS, or through a boot loader? I have been always into computers like palmtops that load DOS from a rom chip. So I am wondering if it's possible to load any type of option using a DOS program or boot loader, through a ROM image on a hard drive. I think it would be possible since I have done something like this , I had a tower that didn't have UEFI support and wanted UEFI support, So I loaded a UEFI BIOS compatible with most computers using a boot loader from a hard drive or flash drive. So i think it would be possible to load a rom directly from DOS or boot loader on a hard drive , or possible a alternate bios that is compatible with all computers, that have a DOS boot option rom, that you can load using a boot loader. if it is possible , I want to know how to do it.
Comments
Basically what you're trying to do is:
Correct?
that isn't correct, I am talking about getting a option ROM or Boot ROM, ROM image to load from a hard drive either from DOS, or using a boot loader. If you don't understand what i'm saying read it again. when I was talking about UEFI, I was comparing what I am talking about to loading UEFI firmware to a computer that only has a standard BIOS by using a boot loader, which is possible. I want to simulate having a option or boot rom load without it being in a standard bios , and load it from a hard drive, with a method above.
That doesn’t make any sense. It usually works the other way around. ROMs emulate a hard disk, perhaps with a few extra tricks built in. At least if we are talking about something like Tandy 1000 series rom disks.
Network option roms are a slightly different story. They are usually designed for booting a diskless workstation. They kind of need to be executed before any other OS loads.
What was the thing you used on the tower that needed UEFI support?
its the same software if you want to make a hackintosh , it's the same bootloader you use since mac os uses uefi to boot. it is also used if you want UEFI support on a computer that only has a bios. The software might be called Clover , I am not totally sure.
It might not make sense but I am asking this for a reason , I designed my own boot rom , only a test rom for now, but I am not sure if it even works , I don't want to add it to the bios rom if it doesn't work correctly. So this is why I am asking the question I want to test the rom to see if it works before I add it, So I am thinking of loading a rom directly into memory and loading it that way, by DOS or a boot loader , or even by chainloading a alternate bios like what erito17 was talking about , with the ROM in it.
Why not test the ROM in QEMU or VirtualBox? I believe both allow custom BIOS ROMs. You could even try PCem.
@Erito17
I want to test it in a real computer as well, I Know about custom roms in QEMU, and Bochs, and PCem, and virtualbox. I have the instructions on adding an option rom to bochs , but nothing else. Also I might have found a way to load it through a bootloader , there is a way apparently using GNU grub.
Maybe you could stick the ROM in the MBR of a hard drive and get the system to boot off of it.
@Erito17
What I've decided to do is use the drive emulation feature of grub4dos , which is a version of GNU grub for DOS, I don't know if the regular version of GNU grub supports it or not, which it probably does. I have confirmed using Virtualbox that grub4dos can emulate a floppy or hard drive and boot from it. The only thing that my boot rom was a custom DOS boot rom. which is emulated the same way using grub.