How to start up Mac when windows is block??

[Phindo]

if anyone know how can i start up mac OS before i have to log into a windows...the problem is my windows os activation has expire and i cannot get into it...i have tried holding shift key after i pres power button but nothing is happening..???it is always trying get me to windows...any idea??? i dont have instalation cd's ..and internet connections...

 

[CylonGlitch]

if anyone know how can i start up mac OS before i have to log into a windows...the problem is my windows os activation has expire and i cannot get into it...i have tried holding shift key after i pres power button but nothing is happening..???it is always trying get me to windows...any idea??? i dont have instalation cd's ..and internet connections...

Hold down the option key when booting; then you'll get the "Option" to boot to a different partition or device.

 

[Rodus]

Hold the alt/option key, that should give you the choice of boot drive.