Master boot record could be corrupt. Have you tried fdisk/mbr on drive 2 from bootable Dos floppy disk then rebooted to the hdd?

I had a hdd with a similar problem, no OS would not boot from it but for some reason OS/2 v3 installed and booted up fine. I left that on it.

I followed your tip to try fdsik/mbr.

You say to use a bootable DOS floppy, but I cant't get one to work. I've tried about all of different bootdisks from allbootdisks.com, but it just won't boot from them.
The only floppy I can boot from is the DOS install, but there I have no other choice then to install.

So I booted up my system to DOS with HDD-1 and HDD-2 as slave.
Then according to this info I could still execute fdisk/mbr, though here it is called cmbr (?)

So I tried that.
FDISK/STATUS says that I have devices number 1 and 2. nr.2 is the one with the problem.
The "FDISK/CMBR 2" command fails. It says -/CMBR invalid.
Then I tried "FDISK/MBR 2". When I run that command the IDE Led lights up for a split second, but nothing happens further, just goes back to C: prompt. Also no error.
After removing HDD-1 and reboot it still won't boot up HDD-2. i.o.w. Nothing has changed.

Should I get some sort of confirmation after executing FDISK/MBR ?

How do you boot from the secondary hard disk? Boot menu selection? Or removing the first one? Was the first one present when you installed the OS on the second one?

I swap HDD's, so there is usualy only one at a time present.
One time only I put them both in so I could boot from HDD-1 to see if HDD-2 acctually worked in the PC, and it did.

In the meantime I'm going another route with this problem.
The reluctant 40GB is going to become a vintage paperweight.
Instead I'm now configuring a 80GB WD HDD. Therefor I had to update my P2b BIOS from version 1012 to 1014, for 60GB> support.
The BIOS flash process has just finished nad has gone well.
I've Fdisked and formatted the 80GB for DOS. As we speak it's hooked up to my i7/win 10 PC as I'm going to copy the WIN95 CD contents to it. The system refuses to find my cd-drive, as all the bootdisks fail.

Martijn1974 wrote on 2021-09-05, 11:29:

I swap HDD's, so there is usualy only one at a time present. One time only I put them both in so I could boot from HDD-1 to see […]
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I swap HDD's, so there is usualy only one at a time present.
One time only I put them both in so I could boot from HDD-1 to see if HDD-2 acctually worked in the PC, and it did.

In the meantime I'm going another route with this problem.
The reluctant 40GB is going to become a vintage paperweight.
Instead I'm now configuring a 80GB WD HDD. Therefor I had to update my P2b BIOS from version 1012 to 1014, for 60GB> support.
The BIOS flash process has just finished nad has gone well.
I've Fdisked and formatted the 80GB for DOS. As we speak it's hooked up to my i7/win 10 PC as I'm going to copy the WIN95 CD contents to it. The system refuses to find my cd-drive, as all the bootdisks fail.

DOS and older versions of Windows will likely refuse to boot, if the partition on the hard disk is not a primary type partition. Had you used another computer with a newer OS to partition and format the hard disk, you could have ended up with an extended partition which DOS/Windows 9x might see, but perhaps will not boot from. Doesn't seem likely since you said you used fdisk/format from the original DOS boot disk.

Also, operating systems like Windows 95 OSR2 (and included version of DOS) can deal with file systems in size up to 32 GB. Older versions of Windows 95 and DOS only support FAT16 and thus disks or volumes up to 2GB. I don't understand how you managed to get DOS/Win 3.11 to operate on HDD1.

I have made a primary partition on HDD-1 using The partition tool on the DOS setup.
When I use the biggest DOS partition option it sets the drive to 2048MB usable space, I believe that's how to get a bigger disk to work.
That same method has been used on HDD-2 but that one refuses to boot, although the DOS installation went fine.

The HDD-1 drive with DOS 6.22 and WIN3.11 runs flawlessly.

Martijn1974 wrote on 2021-09-05, 17:49:

I have made a primary partition on HDD-1 using The partition tool on the DOS setup. When I use the biggest DOS partition option […]
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I have made a primary partition on HDD-1 using The partition tool on the DOS setup.
When I use the biggest DOS partition option it sets the drive to 2048MB usable space, I believe that's how to get a bigger disk to work.
That same method has been used on HDD-2 but that one refuses to boot, although the DOS installation went fine.

The HDD-1 drive with DOS 6.22 and WIN3.11 runs flawlessly.

Right, right - so you're only utilizing 2GB. That makes sense. Is the primary partition on HDD-2 also marked bootable in FDISK?

leonardo wrote on 2021-09-06, 06:22:

...Is the primary partition on HDD-2 also marked bootable in FDISK?

I have looked in FDISK but I can't find any info regarding "Bootable".
I have 1 primary DOS partition of 2048MB.

But... the problem has disapeard.
What have I done? With the help of my Win10 PC I copied the contents of the Win95 CD onto the HDD-2.
Booted with a selfmade bootdisk (Wow, that worked) and started the WIN 95 installation.
That went without any problems and when it was time to reboot the system it powered up and booted right into WIN95.
So now it DOES boot!!
Still don't know what caused the problem, nore what solved it... but it works now.

regards,
Martijn.

Martijn1974 wrote on 2021-09-06, 15:38:

I have looked in FDISK but I can't find any info regarding "Bootable".

It’s called "Active". It shows an "A" in the Status column when the bootable flag is set.

In that case, yes it is active.