If an error occured during read or write operation to hard drive, most likely it has unmarked bad sectors, to which system tries to write. Repartition hard drive (make sure that it doesn't contain diagnostic system) or just run scandisk in through mode, it will scan HDD's surface and mark any bad sectors.

The thing is, it boots just fine on other laptops but not on this one, and every time gives command.com error (it recognises the system and gives drive read error, was in german becouse i wanted to see if its can read german dos at all) its not the first time i am dealing with this, also on my 486 amd desktop it was the same problem not reading command.com from floppy or hard drive. I am afraid it may be corrupted bios memory, sometimes the laptop won't turn on, maybe its ram. I dont have such knowledge to know how to start but i will format it again with dos 5.0 boot disk tommorow. Besides i bought isa controller at the flee market do you think the 486 amd will boot from isa card? I dont know how a isa ide controller works, i dix google it but could'nt find an ansfer.

Hmm, interesting, in such circumstances the inability to boot into OS is usually caused by a unstable system in general. For example, a off spec system bus (on which is present HDD controller) could cause data corruption in files which already exists on HDD. It would also result in storage media's inability to properly access or store files.

I gues on both laptop and desktop PCs you are getting a "bad or missing command Interpreter" error?

manczyslaw wrote:

Besides i bought isa controller at the flee market do you think the 486 amd will boot from isa card? I dont know how a isa ide controller works, i dix google it but could'nt find an ansfer.

That's an easy task, everyone will be to help you with that here 😉, but first make sure that HDD content on desktop PC is not corrupted and system is set as stable as possible.

I would advise you to try to check your HD with a program like MHDD, in the past it has solved problems for me, with installations that failed.
If it finds errors that can be corrected, it should solve them, then anyway it depends on the condition of the disk, if it has too many bad sectors it obviously doesn't work miracles.