Computer system with unattended operation power-saving suspend mode

A portable computer is provided with enhanced power management capabilities. The portable computer includes a power management system which makes a determination as to whether the computer is "user attended" or "user unattended" based upon the position of the display screen in one embodiment. If the display screen is open, then the computer is regarded as being "user attended". In this case, a first timeout delay of I/O inactivity is applied before the computer is permitted to enter a power saving suspend mode. However, if the display screen is closed, then the computer is regarded as being "user unattended". Is this situation, a second timeout delay of I/O inactivity is applied before the computer is allowed to enter the power saving suspend mode. The second timeout delay is generally significantly shorter than the first timeout delay. This technique is found to significantly increase the reliability of I/O activities such as external communications with the computer when the computer is "user unattended".