Hello.
I’ve got a Toshiba T5100 with 386 CPU and 2MB Ram. The original Conner CP342 drive is seized, so I had to figure out something else. Since my 1.3 GB Toshiba HDD connected through 2.5"→3.5" IDE adapter showed the message from Polish Win95 "Brak systemu operacyjnego", I was sure that this machine doesn’t have HDD whitelist and is able to boot from HDD.

I installed the 6GB WD drive with 2 badsectors (according to S.M.A.R.T.). The first thing I had to do was to plug the drive without any jumpers, otherwise computer shows “ERROR ENCOUNTERED INITIALIZING HARD DRIVE CONTROLLER” message. For me that’s quite obvious, because Conner needs to be set as “Single”
Without jumpers, everything seemed to work, so I booted FreeDos on 720k floppy and executed popular program ANYDRIVE.EXE, which allowed me to create 504MB partition. Creating partition and formatting it went well so I just decided to install Toshiba DOS 5.0a. The Installation was going perfectly fine until computer tried to read AUTOEXEC.BAT file on 99% of setup. The hard drive light lit permanently on and after a minute it failed to read from C:.

Trying to read any files copied into HDD ends up exactly the same. HDD light goes on and after a minute or so it says that C: drive is not ready with classic “Fail Ignore Retry Abort” options.
I also tried to copy some files directly to the HDD with other computer, for example TEST3.EXE (the Toshiba diagnostic utility) . Obviously I still can’t read any files or execute any program.
I figured out that it’s possible to boot from this WD HDD, because after performing “sys c:” command in Freedos on clean active partition, Toshiba boots from HDD, starts freedos and hangs in the middle booting with the exact same problem or sometimes showing afterwards an information about missing KERNEL.SYS.

I’m completely out of ideas.
The only thing I can imagine right now is HDD failure or incompatibility of this particular HDD with the machine.