QNX 2 or later

QNX 1.5.x someone has to load in a PC 486? and I need instructions to install it from windows or linux.

Your request isn’t making a lot of sense.

The original QNX version(s) did not have three levels.
I believe that pre 2.0 QNX versions were pre-network. That’s ancient beyond recognition. I don’t know if it supported IDE hard drives.
It’s also very very unlikely that, 1.5 would work on a 486. The most current version 2.21 can have problems on a 486.

What does installing “from windows or linux” mean in this context? These OS’s didn’t exist at the time 1.5 was written.
Are you hoping to install under a VM? That’s possible. The installation would have come on floppy diskettes. If you happen to have such diskettes they are probably 5.25 inch, and maybe should be put in a museum.

Maybe he meant 6.5.0 ?

Maybe, but note the Subject “RE: QNX 2 or later”.
I still don’t know what “Install from windows or Linux” means.