Hi Eric,
> Am 18.01.2025 um 03:01 schrieb Eric Auer via Freedos-devel > <freedos-devel@lists.sourceforge.net>: > > RBIL answers that: > >>> INT 18 - DISKLESS BOOT HOOK (START CASSETTE BASIC) >>> Desc: called when there is no bootable disk available to the system >>> Notes: very few PCs other than those produced by IBM contain BASIC in ROM, >>> so >>> the action is unpredictable on compatibles; this interrupt often >>> reboots the system, and often has no effect at all > > In short, it is not expected to be of any use. I would avoid it. I do not think that we should consider RBIL a single source of truth in that specific case. The use of an INT 18 goes back to at least the MS-DOS 4 IPL [1]. The Win98 IPL also has it. I think this specific page of RBIL might be outdated. It is also recommended method by the BIOS boot specification I mentioned earlier. But as this is from 1996, and we can not expect the INT 18 to work in all cases, we should add a few safety nets: - Check if the INT 18 vector contains a sane value - Display a message and wait a few seconds before issuing the INT 18 - Expect that the INT 18 might return - ... > > [...] > This might be what the boot sector was hoping for, but removing > the 55AA magic and not having it run at all may make more sense. No, the side effects of removing the 55AA magic would be dramatic in the sense that the FreeDOS kernel uses it to decide if there is a partition table [2], as does FDISK itself [3]. I think most programs dealing with the MBR do so. So if we would remove the magic there would be no partitions to install to. [1]: https://hg.pushbx.org/ecm/msdos4/file/6c9e4839690e/src/CMD/FDISK/FDBOOT.ASM#l45 [2]: https://github.com/FDOS/kernel/blob/5de2eb1aa01b0129b046cf06338453a233c6597b/kernel/initdisk.c#L800 [3]: https://github.com/FDOS/fdisk/blob/f9f8cf8379c59dba4a72aa02a94079d56ed60761/source/fdisk/pdiskio.c#L992 Bernd _______________________________________________ Freedos-devel mailing list Freedos-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-devel
