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:

    1. Boot your UEFI firmware-based PC that does not have a CSM (BIOS ROM) built in
    2. Chainload SeaBIOS or some other BIOS ROM
    3. Boot to DOS

    Correct?

  • @Erito17 said:
    Basically what you're trying to do is:

    1. Boot your UEFI firmware-based PC that does not have a CSM (BIOS ROM) built in
    2. Chainload SeaBIOS or some other BIOS ROM
    3. Boot to DOS

    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?

  • @Erito17 said:
    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.

  • @SomeGuy said:
    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.

    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.

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