Patent US 6,018,232

A portable computing device (e.g. a notebook type computer) also includes communications features including a pager receiver and a radio frequency modem which are supported by allowing the device, under application program control, to resume operation from a suspend (sleep) state upon receipt of a paging message. Additionally, depending upon the contents of the paging message, various application programs can be automatically launched in the main processor. Under application program control, the device can operate in a background state with for instance the main screen, its backlight and the keyboard powered down, but with the main processor running at full speed for unattended operation. Under application program control in normal or background mode, the device can request that the unit suspend operation without user intervention, for battery power savings during unattended operations. Under application program control, the device can set the state of a status message indicating a message pending or a urgent message waiting. Thus reception of messages during unattended and/or background state operation is communicated to the user without resuming full operation. Additionally, in response to a drop in output voltage from the battery which is the system power supply, transmission power of the RF modem is reduced, thereby allowing RF modem transmissions over the entire battery discharge curve.