Modern Linux distros usually Grub as a bootloader which installs itself onto the MBR usually. With that in mind, I'm thinking just rewriting the MBR *should* fix that - so booting off a Win95 boot floppy and doing an fdisk /mbr I'm thinking will work here.

Edit: Bear in mind that will mean you wil lose the Linux install, I assume that is what you're intending.

Thank you for that. I’ve tried the command and it’s still a no go, I still can’t boot DOS from the hard drive. Perhaps it is failing but it went through an entire W95 install fairly quickly with no issues.

DOS can only boot from the first primary partition on a HDD.
So perhaps your partitioning is too 'complex' for DOS to boot.
Easiest solution would be to delete all partitions with FDISK and then just create a new primary partition, and set it active.
That should do the trick.

There was only one active partition on the HDD, nothing else... but I deleted it as you said and created another and it’s finally solved my issue! Boots up to the C prompt. For some reason just formatting the drive wasn’t enough. Another old laptop saved! (Once I install W95 anyways)

Actually... the formatted and bootable HDD that now boots fine with no GRUB related errors in my Celeron laptop gives an I/O error in the P1... while at the same time another working Windows 95 HDD boots up fine in the P1 system...

How large is the drive?
Early PCs are notorious for not being able to handle large HDD drives. There are a few 'boundaries' that older BIOSes cannot cross. The solution is to use a 'Dynamic Drive Overlay': https://en.wikipedia.org/wiki/Dynamic_drive_overlay
Basically it's a simple drive that installs into the bootsector (the bootsector can always be read, regardless of how broken/misconfigured the BIOS is... head 0, track 0, sector 0 is always correct), and performs translation for the BIOS to work around the limitations.

So perhaps that is your problem. My Pentium 133 suffered from this issue as well, I couldn't run disks larger than 8.4 GB in it, and I wanted to use a 20 GB disk. I used EZ-BIOS to work around it. Works like a charm.
I also use it on my 486, to get around its 504 MB limit.

(You wouldn't have this problem with GRUB/linux because they contain their own 32-bit drivers which replace the BIOS anyway.. same goes for Windows NT. Only software that uses BIOS directly will suffer from this, which would include DOS and Win9x... It's quite possible that the drive is an aftermarket upgrade, and the issue wasn't there with the stock drive).

The drive I’m trying to boot DOS from is actually the original 2gb drive that came in the P1 laptop, which is a HP Omnibook, P133. In its current configuration the HDD boots to a C prompt in two other laptops but an I/O error in the HP.

As I stated - I have another HDD with a Windows 95 install on it that boots up fine in the HP!

I do however have a couple of 60gb drives knocking around that I could try and use with the dynamic drive overlay just in case it’s the drive at fault...

britain4 wrote:

The drive I’m trying to boot DOS from is actually the original 2gb drive that came in the P1 laptop, which is a HP Omnibook, P133. In its current configuration the HDD boots to a C prompt in two other laptops but an I/O error in the HP.

There is a chance that the original drive was installed with a DDO from the factory (although this is quite unlikely, especially for a brand like HP).

britain4 wrote:

As I stated - I have another HDD with a Windows 95 install on it that boots up fine in the HP!

If that is also a 2 GB or larger drive, then we can rule out that the BIOS needs a DDO (unless a DDO is installed on that drive of course), at least for that size of disk.
In which case I do not know what the problem would be exactly.
Have you tried booting the machine with a floppy, and accessing the HDD that way? Then you might be able to determine whether the HDD works, but is just unable to boot, or if the entire HDD just isn't working in the machine.

Sadly the machine has lost its original floppy drive and the CD drive is not bootable, so I’m pretty stuck.

I went out on a limb and formatted the W95 drive which did boot in the HP (which came from a Toshiba and coincidentally is the same make and model but a smaller capacity) and copied system files over to it from the W95 boot floppy on a different system, it boots fine in that system but now both drives give an I/O error when inserted into the HP.

Either there is a fault with the HP... which would seem odd given that it did boot fine from a drive with W95 already installed on it... or there is something specific it wants to be bootable which I am not getting somehow.

Some manufacturers had a special 'system partition' on the disk, which contained part of the BIOS.
I have a few Compaq Deskpros like that.
Compaq provides some disk images to install this system software on a new harddisk.
Of course you would need a floppy drive to pull that off. Perhaps your HP has the same requirements.

I don't know where to go next then with it, seems like it might be relying on some boot discs I don't have. I tried a HP restore floppy disk image I found but obviously had to try it out in another laptop and it comes up as invalid boot drive.

Seemed to work ok with the original Toshiba copy of W95 but I just tried another drive with working Win98 on it and I got I/O error again.

Don't think I'll be able to sort this out without a disk image from the same laptop 🙁

Might be overkill, but the only thing I can think of at this point is wiping the entire drive by connecting it to a different computer and running DBAN on it, or a different program to zero out every single sector on the drive (There are others, but DBAN is the only one I know the name of off the top of my head)...or at the very least zero out the MBR.

britain4 wrote:

Actually... the formatted and bootable HDD that now boots fine with no GRUB related errors in my Celeron laptop gives an I/O error in the P1... while at the same time another working Windows 95 HDD boots up fine in the P1 system...

I had a similar problem before. I have a 4GB hard drive and on one machine it's automatically detected in Large mode and LBA mode on another. I had to manually set the mode otherwise one machine will refuse to boot.

Scali wrote:

Some manufacturers had a special 'system partition' on the disk, which contained part of the BIOS.
I have a few Compaq Deskpros like that.

Bad idea #283?

Did you type in fdisk /mbr when you booted the diskette and SYS C: as well?

Yup I did fdisk /MBR, no dice. I’ll have to try wiping the drives on another machine and starting again with it at some point. For now I don’t have the time to be messing about with it really 🙁

lazibayer wrote:

britain4 wrote:

Actually... the formatted and bootable HDD that now boots fine with no GRUB related errors in my Celeron laptop gives an I/O error in the P1... while at the same time another working Windows 95 HDD boots up fine in the P1 system...

I had a similar problem before. I have a 4GB hard drive and on one machine it's automatically detected in Large mode and LBA mode on another. I had to manually set the mode otherwise one machine will refuse to boot.

This sounds fairly promising, how does one go about manually setting that?

britain4 wrote:

lazibayer wrote:

I had a similar problem before. I have a 4GB hard drive and on one machine it's automatically detected in Large mode and LBA mode on another. I had to manually set the mode otherwise one machine will refuse to boot.

This sounds fairly promising, how does one go about manually setting that?

In the BIOS setup.

Use ccleaner drive wiper "entire drive"
Active@ Kill disk

or a similar program to zero out an entire drive to avoid issues like this in the future with 2nd hand disks.

Linux like later versions of windows installs a boot loader or recovery partition to a hidden partition on a HDD.

Windows 98 and DOS cannot always see these partitions and it isn't promised it will clear the boot sectors.

Cool thanks guys I’ll five these things a shot, anything is worth trying at this stage. I don’t remember seeing anything about large drives in the BIOS but I might have missed it.

I could try zeroing out the drives and trying again but it’s strange that it happens on both the ex-Linux drive and another that booted fine when it had full W95 on it, but not the system files from the 95 or 98 boot disks.

Weird thing, I tried a hard drive from a Libretto 110ct in it yesterday and it said “invalid system disk” rather than “I/O error”. I bet if I could find a way to load and install Windows from a floppy on the HP itself it would work.