A great many medical devices now contain "embedded software" (often called firmware), which controls their operation and characteristics. Like the "glass cockpit" in today's advanced aircraft, the lights, buttons, and controls on many software-based medical devices have been replaced by color displays and touch screens. Such devices as intravenous pumps, ventilators, anesthesia machines, and glucose meters all contain dedicated microcontrollers that perform the functions of the device under the control of the device-specific software. Other devices consist of more complex systems that may combine specific device-related embedded software combined with workstations and off-the-shelf software that are used to control the functions of the device. There may be other stand-alone software applications that, in and of themselves, may be considered medical devices because of the functionality contained in the software (such as picture archiving and communication systems and laboratory information systems).