Apple iMac (21.5 and 27-inch, Late 2009) - Manual (Page 23)

Chapter 2 Life with Your iMac 23
G Ethernet port (10/100/1000Base-T)
Connect to a high-speed 10/100/1000Base-T Ethernet network, connect a DSL or
cable modem, or connect to another computer and transfer files. The Ethernet
port automatically detects other Ethernet devices.
£ Mini DisplayPort
Output port with support for DVI, VGA, and dual-link DVI. The 27-inch model also
supports input from external DisplayPort sources. Required cables and adapters
are available separately.
d Four high-speed USB (Universal Serial Bus) 2.0 ports
Connect an iPod, iPhone, mouse, keyboard, printer, disk drive, digital camera,
joystick, external USB modem, and more. You can also connect USB 1.1 devices.
, Audio in/optical digital audio in port
Connect an external powered microphone or digital audio equipment. This port
is also a S/PDIF stereo 3.5 mini-phono jack.
f Headphone out/optical digital audio out port
Connect headphones, external powered speakers, or digital audio equipment.
This port is also a S/PDIF stereo 3.5 mini-phono jack.
H FireWire 800 port
Connect high-speed external devices, such as digital video cameras and storage
devices. The port provides up to 7 watts of power.