1

I'm really interested in retrocomputing, and as I was looking for a so-called "pure" version of AT&T UNIX v7 I came across this port to the x86 architecture called v7/x86. It seemed interesting, so I took a crack at downloading it.

However, I ran into a problem. My machine is UEFI-based, and I don't have any other storage devices on me besides my hard drive and v7/x86 CD. Since this OS uses an MBR bootstrap, is it possible to decompile to assembly and write a UEFI bootloader using EDK II for it?

1 Answers1

1

Tentative answer as I've not written any low-level code myself:

If your machine's firmware has a "CSM" or "Legacy boot" option, just use that. It provides full BIOS emulation, from MBR bootstrap to runtime services, and should be able to start v7/x86 as is.

If your machine has no such option at all (which would be rare), then a custom UEFI-based bootloader may be possible but would only work if the OS itself does not rely on any features that BIOS interrupts would provide, because there is no BIOS. (E.g. as far as I know, the plain 80x25 text mode does not exist in UEFI world, and the "disk access" int 13h functions definitely do not.)

grawity
  • 501,077