Just getting my first powerbook 100, no battery needed. It has a battery on off switch on the back by the power port. My ccfl is dead, it needs caps and a hard drive but with a flashlight and external floppy booted to 7.1 no problem. Not sure about the OS but it was after the portable and my portable has like finder 6.0.5 , system 6.0.8 I would think it needs that but it's just a 68000 chip so I don't know.