Older, AT motherboards utilized two connectors, commonly referred to as "P8" and "P9" that were positioned directly next to each other. These supplied +5V, +12V, −5V, −12V, "power-good signal", and ground. The most notable difference from modern 20/24-pin ATX power connectors is that the AT power supply connector did not have a signal to turn on the power supply, and also did not supply separate, "always-on" +5V standby power. The power supply was instead turned on and off via a heavy mechanical switch which removed mains power. Modern, ATX supplies, by contrast, are capable of being switched on and off by the computer itself, and the power button is actually a signal that is received by the motherboard and in turn passed along to the power supply. This allows the motherboard to remove power upon shutdown (with the exception of the aforementioned 5V standby power, which is always on), and also to "wake up" the computer by events such as key presses, mouse clicks, "wake on lan" events, and scheduled alarm times. These "wakeup" features are often configurable via the BIOS/CMOS setup.