I'm not sure. When I bought the drive several years ago I only owned that Macbook Pro so it's quite possible I did. What would I need to do to make it recognizable by both? Then it probably formatted as HFS or HFS+ then. There are some free utilities that let you read HFS from windows but not write. OSX can read NTFS but not write.
If you plan on regularly moving data back and forth paragon's NTFS on Mac or HFS on windows are highly regarded and fairly cheap. You only need one. There are a couple of file systems both can read but they don't handle 1Tb very gracefully.
![Using My Passport Ultra For Mac Using My Passport Ultra For Mac](/uploads/1/2/5/3/125360314/761748518.jpg)
Edit: exFAT would work pretty well for you actually. But only if you have windows 7/8 and OSX snow leopard or newer.
![Using My Passport Ultra For Mac Using My Passport Ultra For Mac](/uploads/1/2/5/3/125360314/669821717.jpg)
For example in my recent review of the Western Digital My Passport, I stated how the device was available in a $150 Windows version and a $160 Mac version. In order to take advantage of accessibility to both operating systems and save $10 I decided to reformat the hard drive myself. Getting Started with a My Passport Ultra How to format a WD hard drive to exFAT or FAT32 file system. Answer ID 291| This answer explains how to format a drive in the exFAT or FAT32 file system. This allows the drive to be used on both Windows and macOS.