[Oberon] Re (2): Copy or reinstall A2?

[Liam Proven]

On Wed, 21 Jul 2021 at 20:52, Michael Schierl <schierlm at gmx.de> wrote:
>
> Even worse: There are *NO* Tools whatsoever that can put an ISO file
> that contains *any* ISO9660 filesystem with an El Torito NoEmulation
> Boot Block to a standard USB flash drive in a way that it will boot (I
> am not talking about those rare flash drives that have a physical switch
> where you can switch them into "emulating" a USB CDROM drive). Ventoy,
> Rufus etc. contain a list of hashes of "well-known" El Torito
> bootloaders and will replace those with MBR-style bootloaders that
> (hopefully) perform the same task. If your tool does not recognize the
> bootloader, you are out of luck.

I did not know that. It explains a lot -- thank you for this valuable
information.

> With EFI boot blocks or Floppy Emulation boot blocks it is easier (most
> EFI boot blocks can cope with both USB and CDROM, and floppy emulation
> boot blocks can be booted from USB using syslinux+memdisk).
>
> Yet still, this bootloader will only load the operating system kernel
> (and maybe some initial ramdisk) into memory. If the OS needs more files
> than just the kernel + initrd, and the kernel is not prepared to scan
> for USB mass storage drives (or has no appropriate driver linked in), it
> will not be possible to boot it from USB as it just cannot find the
> drive to boot from.

Ah, yes, I can see that.

I also spend quite a lot of time experimenting with DOS, itself now a niche OS.

A useful discovery has been that if you boot a DOS USB, the BIOS
emulates a hard disk and DOS thinks  it's running on a read-write hard
disk drive. This being an OS with no direct USB support of its own at
all.

So, normally, if you plug a USB drive with a DOS-readable filesystem
(FAT12, FAT16, FAT32, etc.) into a DOS PC, nothing happens.

But the BIOS emulation has some desirable side-effects. If you boot a
DOS USB _with a 2nd USB drive inserted_ then DOS can see that too, for
instance.

I have been considering trying to build some bootable images of DOS
with Oberon-for-DOS installed and ready to run. Not sure if anyone
would be interested in that. It may be a way to have a live bootable
Oberon environment, for example, without needing Oberon to support
this.


> So, when you want to boot exotic OSes from CD (even if they use real
> ISO9660 filesystems), either get a real CD drive, get one of those flash
> drives that can emulate a CD drive in hardware, or put the ISO into a
> virtual machine.

Ventoy has been working very well for me, but this is a strong
argument for a real hardware-level emulator.


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