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First post, by Cyber Akuma

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Wondering if anyone had any good advice on this. I have a Pentium 4 laptop that other than not having a HDD currently installed works perfectly, it has both a DVD-ROM and Floppy drive in it. I wanted to use it to boot a live OS without installing it to dump backup images of some of my floppies, but I am not sure the best way to go about that.

I have bootable DOS 6.22 ISOs, but they work by creating a virtual floppy drive and booting off that, which interferes with the real floppy drive. Is there any way to boot it to a RAMDISK that mimics a HDD or something instead?

Or can I use Freedos? Freedos seems... overkill for such an old system, and I am not too familiar with it, not sure how well it would support the hardware. Although from my understanding USB flashdrives work in it so that would make getting data off the computer easier.

And in the case of either, what DOS/Freedos software can I use to create backup images of my floppy disks? Preferably in ima or img format.

Reply 1 of 16, by elszgensa

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Use a Linux LiveCD/-USB, then 'dd' those floppies straight onto an USB stick. Or, if you prefer, some kind of live Windows disc (I recall people raving about BartPE, no idea whether that's still the case), then WinImage.
But if you insist on making life unnecessarily hard for yourself, I can at least point you to FreeDOS' raread/rawrite.

Reply 3 of 16, by wbahnassi

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I image my disks to .IMD where possible. For a setup like yours, I have a USB stick with DOS 6.22 and ImageDisk on it. Put it in the PC and boot from it. It becomes the C: drive so you won't need an HDD in the machine at all. Image the disks to C: drive and shut down and transfer the files into final storage.

Reply 4 of 16, by kdr

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Hiren's Boot CD (verison 10.6) is full of vintage DOS and Windows utils from the P4 era, it has a live Mini XP and a live mini Linux which are both loaded with useful programs. It's my go-to disc for any retro machine with a BIOS new enough to boot from CD-ROM. Easy enough to find a copy of Hiren's from the usual places.

Reply 6 of 16, by wierd_w

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Check out isolinux + memdisk.

I have created fully bootable win9x 'installs' this way.

For win98, you need at least 384 mb to allocate for the 'ramdisk', and you need to make aggressive use of drivespace3 compression with ultrapack.

This means your P4 needs at least 1gb of RAM present.

In a nutshell:

1) create a 384mb flat disk image, and configure it for use in a pc emulator of your choice. (Bochs, qemu, virtual pc, vmware, whatever.)

2) use Dos 6.22's drivespace utility to compress it, empty.

3) install win9x, and be miserly. Avoid installing pointless and outdated stuff, like 'online services', but keep useful stuff like hyperterminal.

4) install the universal ata driver, and the universal vesa video driver. (Unless you are tailoring this for a single, known system, and have the drivers. Some VM software gives good enough configurability to properly set that up. Caveat emptor.)

5) once installed, convert to drivespace 3, then run the disk packer. You may be able to get IE6 and pals on after doing so, depending on the install options you picked.

6) once you have it 'the way you want it', gracefully down the VM, then copy off the raw flat disk image.

7) configure ISO linux's mkisofs process, to make a menu entry calling 'memdisk' as the kernel, and your flat hdd image as the initrd. Set it as the default boot option. (You can set up OTHER images this way as well, like 100mb dos 6.22 images, freedos images, etc... that have all the dos network stack whizbangs and useful utilities installed and ready to use also!)

😎 burn the resulting .iso image, boot it, and enjoy.

More:

Memdisk is a small int13 and int15 interception program, that allocates xms memory BEFORE the OS loads, then subtracts the size used from the reported size from an int15 call. It then responds to int13 calls, using this block of 'owned' memory.

It is sufficient to fully and completely boot dos and win9x entirely from the ramdisk it provides, with no additional drivers. (Though win9x will complain mightily about being in 'msdos compatability mode' under the performance system properties window. I guarantee you, though, it is far and away faster than any actual disk controller, even with jumping to realmode to do disk io.)

Boot time can be very protracted, however. Reading 384mb of data into RAM takes awhile from a CD drive.

I mention win9x, because of its small footprint, and the availability of old versions of things like winimage that will run on it just fine.

Reply 7 of 16, by progman.exe

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wierd_w wrote on 2024-02-20, 15:16:

Check out isolinux + memdisk.

I have created fully bootable win9x 'installs' this way.
....

I didn't know higher than 95a could be network booted. It sounds very much like your process can just use pxelinux and memdisk, instead of isolinux and memdisk to get round the 95a limitation (if that is even a thing? Maybe only 95a can be booted off NT4 server or something?).

I think I have a 98 VM sitting right here I might try and co-opt....

Cheers for the instructions. What will be a slow thought will be pulling down the HDD image by TFTP

Reply 8 of 16, by wierd_w

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I have booted win98se off a cd this way quite well.

NT4 and pals need a special driver slipstreamed into the image, because they dont use int15 or int13 interfaces after ntldr.

Syslinux's page lists several such drivers that identify, mount, and make use of memdisk provided ramdisks for such OSes, so XP and pals 'can' be used, but need additional steps in the disk image preparation phase to incorporate those drivers.

And yes, memdisk works just fine with pxelinux.

(In theory, if you wanted to wait the 15minutes to an hour needed to TFTP a large, fully prepared NT4, Win2k, or WinXP disk image, booting a fully diskless workstation over PXE is legit totally possible this way ... ... but why? I made a 'Avast antivirus scanning suite' dvd, and took advantage of the speedier access this afforded, and boot time was still quite poor. On modern systems with GRUB, memdisk hosted OSes make a GREAT way to cram a DOS or win9x install along side a linux install. GRUB can read btrfs and ext4fs, load the disk image speedily from the HDD, then boot it. Memdisk is a VERY useful little thing.)

98se is bigger though. You need a 512mb disk image for that one. 🙁

Reply 10 of 16, by GulchWinder3D

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I know the iPXE website has a guide on netbooting and installing XP and later to an iSCSI disk. I don't think a PXE and TFTP server would be necessary in that case since you can write an iPXE image to a floppy, CD, or your NIC's EEPROM, but you'll need another host to provide an iSCSI target. I know TrueNAS has a way to configure iSCSI targets and I've used tgtd on Linux in the past to host disk images in a pinch.

Reply 11 of 16, by megatron-uk

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No need for an iscsi target or a full windows image loaded over the network.

As the previous poster suggested, you can supply a virtual disk/floppy image with pxelinux and memdisk.

Just drop a bootable Dos floppy into an image, put on your packet drivers for your network card, and the new mtcp suite, a disk imaging tool and you have a network booting, Dos image that can write those floppy images back over the network to a virtual disk/folder in your server.

That should be doable in 1.4mb:

Strip down a win98se boot floppy.
Add your NIC packet driver.
Add the latest mtcp suite and either configure to use the new networked virtual disk feature, or just use ftp
Add in imagedisk (if that is appropriate).
Create a ramdrive big enough to save the floppy image to.

That should fit well within 1.4mb, but compress the lot and expand into a ramdrive if needed.
You can probably automate almost all of it via autoexec, too.

I don't do any of the imaging stuff myself, but I do use up to the point of booting a custom Dos floppy image by pxelinux, it's pretty straightforward if you have any Linux experience and a bit of patience, and useful for firmware flashing on systems where the only tool is Dos based.

My collection database and technical wiki:
https://www.target-earth.net

Reply 12 of 16, by megatron-uk

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Heres a pre-written pxelinux/syslinux config entry to get people started:

https://www.target-earth.net/wiki/doku.php?id … log:netboot_dos

My collection database and technical wiki:
https://www.target-earth.net

Reply 13 of 16, by hwertz

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FreeDOS would indeed work; I used rawrite a long time ago to write floppies from DOS (for my first Linux distro) and I think it can read in floppies and write the images as well.

In addition, I will comment, you do still have a choice of several slim Linux distros. Puppy Linux and Damn Small Linux recommend 128MB, but that's running the browser and everything. Just opening up a terminal, popping in a usb drive to write the disk images onto, and running "dd if=/dev/fd0 of=/wherever/floppy.img bs=512" in it is not going to use much RAM at all. Given it's a P4 it probably has at least 256-512MB so should be no problem some larger lightweight distros either.

Reply 14 of 16, by Cyber Akuma

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Seems I have a lot of options to look into, might be best to start with a liveCD of freedos and then try a Linux distro if that doesn't work out.

Since there is potential to wipe the floppies if I do anything wrong, I just want to double-check since now I am doubting everything. The write-protect tap on the floppies is a hard physical protection and no software will override it right?

Reply 15 of 16, by megatron-uk

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Yes, the write protect switch prevents the drive from writing to the disk... As long as the drive is working correctly!

Faulty heads etc can still touch the disk itself ... So you should check that the drive is working correctly first.

My collection database and technical wiki:
https://www.target-earth.net

Reply 16 of 16, by myne

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Cyber Akuma wrote on 2024-02-17, 23:12:

I have bootable DOS 6.22 ISOs, but they work by creating a virtual floppy drive and booting off that, which interferes with the real floppy drive. Is there any way to boot it to a RAMDISK that mimics a HDD or something instead?

I just realised you wrote this.
You know you can use B: for the physical, right?
Shouldn't even have to swap the cables.

Just boot from the iso (a:) and use B: for your floppies.