A power supply circuit for a computer system includes an AC adapter
designed to be connectable to the computer system and supplying power to
the system, a main battery and a second battery that are designed to be
connectable to the computer system and get charged with power from the AC
adapter and then discharge it to supply power to the system, a charger
that is a charging circuit for the main battery and/or the second battery
while the main battery and/or the second battery is connected to the AC
adapter with the computer system powered off, and a gate array circuit
for turning off the power supply to an embedded controller.