What is AirPort? What is AirPort Extreme?

AirPort (802.11) provides a maximum wireless data rate of 11 megabits per second, and AirPort Extreme (802.11g) provides a maximum wireless data rate of 54 megabits per second, which is five times faster. AirPort Extreme is backwards-compatible with AirPort, and works in much the same way. However, it is worth noting that at 54 megabits per second, the "Base Station range" is only 50 feet, whereas the range is 150 feet at 11 megabits per second.

All Intel-based iMac models are capable of at least 802.11g wireless networking.

Does the White iMac "Core Duo/Core 2 Duo" support 802.11a?

Apple's technical specifications for the White iMac models simply state that it provides "built-in 54-Mbps AirPort Extreme wireless networking (based on 802.11g standard)".

However, on page 108 of the original iMac "Core Duo" User's Guide, there is a small blurb under the "Europe--EU Declaration of Conformity" statement that mentions an "802.11a/b/g Mini-PCIe card", which indicates that the hardware is capable of supporting 802.11a.

Some sources mentioned that this inclusion simply was because Apple switched to using Atheros processors to provide Wi-Fi, but Wi-Fi Net News reported that "both Atheros and Broadcom chips are specified in Apple documents and are shown in FCC filings". Based on a photo from the Japanese PC Watch website, Apple seems to be using the Broadcom BCM4311 in at least some of the iMac "Core Duo" systems. Although no official information is available, it seems like Apple also might use the Atheros AR5006EX in some iMac "Core Duo" models, as it appears to provide similar capabilities.

Several readers additionally have confirmed that all Intel-based iMac models -- "Core Duo" as well as subsequent systems -- work with an 802.11a network.

What is the difference between 802.11a and 802.11g (AirPort Extreme)?

SearchNetworking.com notes that 802.11a "operate[s] at radio frequencies between 5.725 GHz and 5.850 GHz. . . [and] data speeds as high as 54 Mbps are possible. There is less interference with 802.11a than with 802.11b, because 802.11a provides more available channels, and because the frequency spectrum employed by 802.11b (2.400 GHz to 2.4835 GHz) is shared with various household appliances and medical devices."

It is also worth noting that 802.11g (AirPort Extreme) also offers data speeds as high as 54 Mbps and is backwards compatible with 802.11b (AirPort). However, data speeds on 802.11g (AirPort Extreme) networks are reduced by the same interference that plagues 802.11b (AirPort) networks as well as the presence of devices using the older 802.11b standard. As a result, deploying 802.11a may make sense in environments where speed is more important than backwards compatibility.

Do the White iMac "Core Duo/Core 2 Duo" models support 802.11n?

The iMac "Core Duo" models do not support 802.11n. All subsequent Intel-based iMac models -- with the exception of the iMac "Core 2 Duo" 1.83 17-Inch -- support 802.11n, but the "White" Core 2 Duo models require a firmware update before it is available for use.

For the wireless capabilities of all "recent" -- G3 and later -- Macs, please refer to the AirPort Capability listing.

Also see: What is is 802.11n? How is it different from 802.11b, 802.11g, and 802.11a?

Did the White iMac "Core Duo/Core 2 Duo" models ship with a modem?

No. None of the Intel-based Macs (iMac or otherwise), come with a modem. Apple offers the compact external "Apple USB Modem" for US$49 for those who need a modem.