If you happen to work on OSX with MacPorts and GPGTools using SmartCard for SSH then installing OpenSC (0.16.0 in my case) will break your smart card access for GPG/SSH. If you remove OpenSC with an uninstall utility things get back to normal.

In order to create OSX installer on USB memory drive you need to:

• Download the Mac OSX Yosemite installer from AppStore on you Mac.
• Create installation media from Terminal by executing following command (remember to adjust YOURUSBVOLUME value):
  
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/YOURUSBVOLUME --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction

• Boot target Mac from USB by pressing ALT/OPTION key while powering-on the computer.
• Remember to format target drive first with Disk Utility if you want to perform clean installation.

In case you wonder why your device does not connect as Modem via Bluetooth to the Mac OSX, or you cannot see COM port on Windows, your mobile device may not simply support or provide DUN (Dial Up Network) and/or SPP (Serial Port Profile) profile.

On Mac OSX I got following error, until I tried another device and/or starting by hand DUN service on a mobile/client machine:

cannot open /dev/cu.Bluetooth-Modem: Resource busy

Notes:

• Read Bluetooth specification for Serial Port Profile.
• Read Bluetooth specification for Dial-Up Network Profile.
• Modern mobile phones / USB 3G dongles, unfortunately, do not provide direct AT/Hayes access to the Radio Modem anymore.
• You can install DUN application for your smartphone, but it will be only a simple dummy wrapper imitating modem for simple applications, but they do not provide full modem functionality, beware, its a fake.
• Its only necessary for devices to be paired first in order to get SPP/DUN working. If device does not provide serial port over bluetooth when devices are paired and online, probably its just not there implemented.

If you want to perform a fresh installation of OSX 10.10 Yosemite on an older MacBook(Pro) you can obtain the installer with AppStore and then create the USB installation media.

In case you encounter an Installer Verification Error that prevents you from installing the new system try the following. Its not the system date not bad download as internets says.

This may also help you when encountering problems (i.e. USB Mass Storage) after system upgrade to Yosemite.

Try these boot keyboard shortcuts until you hear boot sound two times:

• Cmd+Alt+R+P when powering on the Mac (NVRAM Reset)
• Alt+Ctrl+Shift+PowerON alltogether (SMC Reset)

No problem, you are wolcome :-)

I have, finally, switched to Apple OS X. This is so close to my favorite FreeBSD (OSX is a Unix BSD / Darwin derivative) and it has all drivers and multimedia features working, that I think I will switch for good. This the simple, stable, and functional platform, where you can really focus on your work. Along with the MacPorts suite installed that provide access to the Open-Source / Free-Software I feel like home :-)