What happens when you try to play a backup game in a psx without modchip or bootcd?

By the sounds of what you are saying then spooky has already answered the question.

If the PSX console isn't chipped then it should enter the ' CD player ' or ' memory card ' screen if you insert a copied game.

If the game is reaching the black PSX screen then there must be some form of modification as this the boot -up process of the disc and therefore the Psx console is recognising the disc.