The smaller iMac gets a 4K display, all the 27-inch models have 5K

Apple's big fall keynote happened more than a month ago, so it's a bit late for Tim Cook to be saying "one more thing." Sure enough, though, the company just unveiled a refreshed line of iMacs, including a 21.5-inch model with an optional 4K (4,096 x 2,304) screen. That last bit shouldn't come as a surprise: The internet has already been abuzz with rumors that the smaller iMac would finally get a Retina display option, as opposed to just plain old 1080p. All told, the 4K iMac has 4.5 times the resolution of Full HD, with the same pixel density as the 5K version. Speaking of the sort, the 27-inch model now comes standard with a 5,120 x 2,880 panel, whereas 5K resolution was once reserved for a $2,499 flagship edition. Across the board, both the 4K and 5K iMacs bring a 25 percent wider color range, and upgrading to Apple's hybrid Fusion Drives costs about half as much as it used to ($100, down from $200 to $250). That said, it's a shame that 5,400 rpm HDDs are still the standard throughout much of the iMac lineup.

In addition, Apple redesigned its mouse, wireless keyboard and Magic Trackpad with built-in batteries that recharge via a Lightning cable (fricking finally). The keyboard in particular now takes up 13 percent less space on your desk, but still has larger buttons, while the Trackpad now has 29 percent more surface area and supports pressure-sensitive Force Touch gestures. The mouse basically looks the same, and supports the same multitouch gestures as ever, but it's lighter and redesigned feet on the bottom promise smoother gliding.

Under the hood, the 27-inch model steps up to sixth-generation Intel Core processors and AMD R9 M300-series graphics. The 21.5-inch version is no longer offered with a discrete GPU, and instead makes use of Intel's higher-end integrated graphics, the Iris Pro 6200 chipset. As it happens, the only desktop chips that pair with Intel's Iris Pro graphics are from Intel's fifth-generation Core series, but before you get too upset, know that these particular chips were only released a few months ago, so it's not like they're old, exactly. Still, it's a bummer that the dedicated GPU has been axed just as the 4K Retina display is arriving, though chances are, if you had your heart set on a dedicated GPU, you would have been more likely to go with the 27-inch edition anyway.

The new iMacs are available today and as it happens, we've already published a review of the 4K 21.5-inch model. If you choose to buy one yourself, the starting prices are the same as before: $1,099 for the smaller edition and $1,799 for the 27-incher. If you want the 4K iMac in particular, that starts at $1,499. Each comes standard with the keyboard and mouse, though you can swap in the trackpad for an extra $50, or choose to have both in the box. By the way, if you own an old iMac, you can purchase the new input devices individually, with the keyboard prices at $99, the mouse at $79 and the trackpad at $129.