4 ms·

> Oh yes, there are some old computers that won't boot from USB Back in the day, there were some old computers that wouldn't boot from a CD drive. I recall tha

by cesarb 5y ago

> Oh yes, there are some old computers that won't boot from USB Back in the day, there were some old computers that wouldn't boot from a CD drive. I recall that the solution back then was very simple: within the ISO image, there was a bootable floppy image, which you could write to a normal floppy disk (actualy, there were IIRC usually two such images, one for 1.44 floppy drives, and another for the older 1.2 floppy drives). You would boot and load the kernel from that floppy, but the installer would look for the rest of the files on the CD drive. The same idea could be used here: for those old computers which have a BIOS which do not understand how to boot from a USB drive, a small bootable CD image containing only the bootloader and the kernel could be made available, either within the USB image or as a separate download.

bitwize 5y ago
ISO 9660 discs still have bootable floppy images in them. The El Torito standard for bootable CDs specifies that a floppy image be incorporated into the disc image. The PC BIOS knows how to find this image, load it into memory, and boot it as a virtual floppy. But of course, ugly hacks like this were only ever a peecee problem. Macs could boot CD-ROMs like any other drive for as long as they've had CD-ROMs.
- kevin_thibedeau 5y ago
  It's actually one of three possible images: floppy, HD MBR, or raw binary.
- AshamedCaptain 5y ago
  > But of course, ugly hacks like this were only ever a peecee problem. Macs could boot CD-ROMs like any other drive for as long as they've had CD-ROMs. This is a bit ridiculous, since in order to be bootable, a Mac requires the CD-ROM to contain a HFS filesystem. PCs could also boot "like any other drive" from CD-ROM if they forced the CD-ROMs to contain a MBR. Actually, that is exactly what El Torito is: putting a boot record on a CDROM, so that it can boot "like any other drive". The fact that the boot record is most commonly found in an image of a floppy disk is an implementation detail (you can have whatever you want, it's just that floppy is easier to work with), and hardly "a hack". "A hack" would be to force the CD-ROM to contain a hybridized HFS filesystem, despite the entire raison d'être for ISO being to avoid having to put multiple filesystems in CDs.
  - p_l 5y ago
    ElTorito doesn't include normal boot record on the CD-ROM. Placing MBR or similar is a hack used among other things to support the ability to "burn" image to disk drive that is not CD/DVD. El-Torito specifies a bunch of different possible images, among them floppy images (used by Win9x boot CDs) and native images (used by most linux bootloaders and by later WinNT versions), and there's IIRC separate type for UEFI bootloader. There's still space left in front of the CD allowing for bootsector tricks, which is also how hybrid HFS+ disks work at all (there's space to fit necessary volume header, and Mac booting uses HFS+ "blessed file" pointer to find boot image).
Retr0id 5y ago
I use to use a boot CD called "plop boot manager" for this purpose: https://www.plop.at/en/bootmanager/download.html https://www.plop.at/en/bootmanager/download.html
seoaeu 5y ago
If we're doing two phases, I'd much rather the first be CD drive and the second stage be over the network
- Operyl 5y ago
  I have a feeling the people with these issues wouldn’t appreciate their (likely limited) networks being saturated.
jmrm 5y ago
That's totally true. You can use Plop Boot Manager to boot any CD, external hard drive, or USB stick from a floppy disk.
icedchai 5y ago
For a while, in 1994, I had some weird SCSI card (soundblaster with SCSI, I think) that couldn't boot Linux off a harddrive. (It probably could, I just couldn't get it to work...) So I just left a floppy with a kernel in the drive. The system was generally running 24/7, but I wanted it there in case it did reboot...
- tehbeard 5y ago
  > some weird SCSI card (soundblaster with SCSI, I think) I can't help but imagine it as working similiar to the Floppotron... https://www.youtube.com/watch?v=oGfkPCZYfFw https://www.youtube.com/watch?v=oGfkPCZYfFw

by cesarb 5y ago

bitwize 5y ago

ISO 9660 discs still have bootable floppy images in them. The El Torito standard for bootable CDs specifies that a floppy image be incorporated into the disc image. The PC BIOS knows how to find this image, load it into memory, and boot it as a virtual floppy. But of course, ugly hacks like this were only ever a peecee problem. Macs could boot CD-ROMs like any other drive for as long as they've had CD-ROMs.

kevin_thibedeau 5y ago
It's actually one of three possible images: floppy, HD MBR, or raw binary.
AshamedCaptain 5y ago
> But of course, ugly hacks like this were only ever a peecee problem. Macs could boot CD-ROMs like any other drive for as long as they've had CD-ROMs. This is a bit ridiculous, since in order to be bootable, a Mac requires the CD-ROM to contain a HFS filesystem. PCs could also boot "like any other drive" from CD-ROM if they forced the CD-ROMs to contain a MBR. Actually, that is exactly what El Torito is: putting a boot record on a CDROM, so that it can boot "like any other drive". The fact that the boot record is most commonly found in an image of a floppy disk is an implementation detail (you can have whatever you want, it's just that floppy is easier to work with), and hardly "a hack". "A hack" would be to force the CD-ROM to contain a hybridized HFS filesystem, despite the entire raison d'être for ISO being to avoid having to put multiple filesystems in CDs.
- p_l 5y ago
  ElTorito doesn't include normal boot record on the CD-ROM. Placing MBR or similar is a hack used among other things to support the ability to "burn" image to disk drive that is not CD/DVD. El-Torito specifies a bunch of different possible images, among them floppy images (used by Win9x boot CDs) and native images (used by most linux bootloaders and by later WinNT versions), and there's IIRC separate type for UEFI bootloader. There's still space left in front of the CD allowing for bootsector tricks, which is also how hybrid HFS+ disks work at all (there's space to fit necessary volume header, and Mac booting uses HFS+ "blessed file" pointer to find boot image).

Retr0id 5y ago

I use to use a boot CD called "plop boot manager" for this purpose: https://www.plop.at/en/bootmanager/download.html https://www.plop.at/en/bootmanager/download.html

seoaeu 5y ago

If we're doing two phases, I'd much rather the first be CD drive and the second stage be over the network

Operyl 5y ago
I have a feeling the people with these issues wouldn’t appreciate their (likely limited) networks being saturated.

jmrm 5y ago

That's totally true. You can use Plop Boot Manager to boot any CD, external hard drive, or USB stick from a floppy disk.

icedchai 5y ago

For a while, in 1994, I had some weird SCSI card (soundblaster with SCSI, I think) that couldn't boot Linux off a harddrive. (It probably could, I just couldn't get it to work...) So I just left a floppy with a kernel in the drive. The system was generally running 24/7, but I wanted it there in case it did reboot...

tehbeard 5y ago
> some weird SCSI card (soundblaster with SCSI, I think) I can't help but imagine it as working similiar to the Floppotron... https://www.youtube.com/watch?v=oGfkPCZYfFw https://www.youtube.com/watch?v=oGfkPCZYfFw