ps2 info

A few weeks ago my friend gave me his "chipped" ps2 that stopped working (the platter motor was bust) and i just put it in a cupboard cos i had a lot of work on at the time, anyway today i thought i'd have a go at repairing it so i got it out and the first thing i did was check what model it is "DTL-H30001S" and it says debugging console on the back aswell , but it says ps2 on the top not "test" anyway i opened it up and changed the platter motor and checked for a chip which i didnt find so i put a backup game in and it ran fine ,so i have got a genuine debug console FOR FREE :dance: but what i wanted to know was why does it say ps2 on the top and not test?? and what other uses does a debug console have????