1. Click on the top left corner of the toolbar (Apple logo) logo, about this machine--more information--system report--(in the left sidebar) software (some computers are not for example the first picture )
2. Enter Command uname-a carriage return
X86_64 indicates that the system is 64-bit
The i686 represents the system 32-bit
3. Ioreg-l-P Iodevicetree | grep "Firmware-abi" | Sed-e ' s/[^0-9a-z]//g '
How do I see how many Mac OS?