VOGONS


First post, by mike_canada

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I'm making a project for an old computer. So far I am able to make the CD boot on the computer like a floppy disk by inserting a pre-made image found at https://www.allbootdisks.com/ into the CD ISO via a Linux CD burning program, K3B.

Here's the sad part. I'm limited to using only 1.4MB off the entire 650MB CD. Why? because I haven't figured out how to make a boot image of a hard drive (instead of a floppy), and the CD-ROM drive is external and attached to the computer and no DOS CD-ROM drivers work with it. And this isn't an ordinary computer. It's a DELL thin client machine.

Now making a hard drive bootable image from scratch is tough and I'd like help doing it.

So far, I did create a 256MB image file by executing this in linux:

dd if=/dev/null of=image.img bs=1M seek=256

I can control what files are in it using linux mount. I can partition it as a FAT16 or FAT32. I even used mkdosfs (mkfs.vfat) to try to make it a DOS based file system with a 256MB disk.

I tried to see if I can do anything in DOSBOX to make the image file a bootable hard drive image for the CD, and I have no luck with the IMGMOUNT command.

I also have mtools package installed for linux but the mformat command is risky because it expects me to use a drive letter as a parameter and linux doesn't use drive letters.

Perhaps there's a unix utility I need to download and use to make the image as bootable so when I put the CD in the non-bootable computer, it will boot as if the computer is booting off from a second hard drive instead of a floppy disk.

Any ideas on how I can solve this?

Reply 1 of 6, by jmarsh

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Use the 1.44MB image to load a cd driver and mscdex to access the rest of the CD through another drive letter.

Reply 2 of 6, by Cyberdyne

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There is an option for a HDD emulation, but the BIOS support is more spotty for that, so yes, make a bootable floppy image, with CD drivers and MSCDEX and you can access the rest of the CD/DVD-ROM.

Bart's tools even have some utilities for finding a CD rom drive letter and then you just use %CD% in your batch files.

I am aroused about any X86 motherboard that has full functional ISA slot. I think i have problem. Not really into that original (Turbo) XT,286,386 and CGA/EGA stuff. So just a DOS nut.
PS. If I upload RAR, it is a 16-bit DOS RAR Version 2.50.

Reply 3 of 6, by Jo22

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Rufus has HDD emulation for CD-ROMs..
Not sure if it works for or this scenario, though.
http://rufus.ie/

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In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Reply 4 of 6, by mike_canada

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Cyberdyne wrote on 2021-01-28, 08:17:

There is an option for a HDD emulation, but the BIOS support is more spotty for that, so yes, make a bootable floppy image, with CD drivers and MSCDEX and you can access the rest of the CD/DVD-ROM.

That was the method I tried to use with quite a few generic CD-ROM drivers but none would load properly in config.sys and unless I can get one running in config.sys, MSCDEX will be of no use.

The CD/DVD drive in question is an external USB one.

Reply 5 of 6, by superfury

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Afaik MS-DOS USB CD-ROM drivers don't exist? Normal CD-ROM drivers(ATAPI on the motherboard without USB) have lots of drivers though(OAKCDROM, VIDE-CDD etc.).

For that matter, afaik USB and everything connected to it is completely unsupported in MS-DOS anyways.

The only alternative of ATA/ATAPI CD-ROM drivers I know of is that there exist some CD-ROM drivers that use the serial or parallel port I think (don't remember which of those two it was for)?

The BIOS might have support for CD-ROM containing a bootable hard disk image. You'll have to properly configure the ISO creating tool for that, though. It's just replacing the floppy disk image with a hard disk image that's bootable, combined with the configuration of a hard disk boot instead of a floppy disk boot. Thus using an El Torito HDD boot from CD-ROM instead of an El Torito floppy boot.

Author of the UniPCemu emulator.
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Reply 6 of 6, by chinny22

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You can get a bit more then 1.44mb easy enough by having the boot disk create a ram disk just like the generic Win98 boot disk does.
Don't know if that'll help just throwing out ideas