ati man page
ati — ATI video driver
Section "Device" Identifier "devname" Driver "ati" ... EndSection
ati is an Xorg wrapper driver for ATI video cards. It autodetects whether your hardware has a Radeon, Rage 128, or Mach64 or earlier class of chipset, and loads the radeon(4), r128(4), or mach64 driver as appropriate.
The ati driver supports Radeon, Rage 128, and Mach64 and earlier chipsets by loading those drivers. See those manpages for specific cards supported.
Please refer to xorg.conf(5) for general configuration details, and the specific card driver for driver configuration details.
Xorg(1), xorg.conf(5), Xserver(1), X(7), r128(4), radeon(4)
See the individual driver pages for authors.