Abstract: An electronic device includes a display, a connector to which an external video signal is input, and a control unit which performs signal switching with respect to an internal display signal and the external video signal input to the connector to display one of these signals on the display.

Abstract: A memory device is constructed by connecting a plurality of flat high-speed memory modules each including a connector on one side of which input side and output side terminals for dealing with a high-speed signal of plural-bit width whose impedance is controlled and which is transmitted from a memory controller to a terminal resistor are arranged. The memory device in which memory modules can be cascade-connected and which can maintain the impedance of a memory bus signal in a constant value by use of an inexpensive multi-layered circuit board structure is provided. A socket mounting structure of the memory device and a mounting method of the memory device is provided.

Abstract: A battery charge circuit using a constant voltage/constant current to power charge a plurality of battery packs, a current detection circuit to detect a charge current according to a predetermined value, and control mechanisms to maintain a constant voltage charge mode when the charge current value drops below a set value within the battery pack.

Abstract: In a battery-driven portable computer, a battery pack is constituted by m battery sets connected in series each including n lithium-ion secondary battery cells connected in parallel. A voltage monitor for monitoring the voltage of the terminal electrode of each battery set and a charger for independently appropriately charging each battery set in accordance with a monitor result are arranged, thereby realizing battery driving by a lithium-ion secondary battery pack having a large capacity. A computer system monitors the voltages of the battery cells which are part of a secondary battery by comparing the battery voltages with a predetermined voltage value in order to detect overdischarge (undervoltage) or overcharge (overvoltage), outputs this information outside of the battery pack, and terminates processing prior to a circuit disconnect.

Abstract: In a battery-driven portable computer, a battery pack is constituted by m battery sets connected in series each including n lithium-ion secondary battery cells connected in parallel. A voltage monitor for monitoring the voltage of the terminal electrode of each battery set and a charger for independently appropriately charging each battery set in accordance with a monitor result are arranged, thereby realizing battery driving by a lithium-ion secondary battery pack having a large capacity.

Abstract: Upon detecting removal of a display section from a computer unit's main body, dismounting a battery, removal of a memory board from the computer unit's main body or the like, the CPU saves system data no matter whether or not the resume mode is on and turns off the main power supply. Subsequently when the power switch is turned on the CPU checking if said system data is saved. The CPU restores said system data and restarts the data processing in case where the preservation of said system data is detected.

Abstract: A personal computer of this invention has a battery pack mounting section for detachably receiving battery packs having different current capacities. The personal computer also includes a switch mechanism for detecting whether a battery pack has a high or low capacity. Battery characteristic values consisting of charge and discharge voltage/current characteristics in units of batteries are prestored in a memory in a power control CPU (PC-CPU). The PC-CPU refers to the memory on the basis of capacity data from the switch mechanism and reads out the corresponding battery characteristic data. A power supply circuit performs optimal charge control on the basis of this characteristic data. Two battery packs are prepared. When the PC-CPU detects that the currently used battery pack is in a low-battery state, it selects the other battery pack to supply the operating power to the personal computer. At the same time the PC-CPU performs optimal charge control of the battery in the low-battery state.

Abstract: Upon detecting removal of a display section from a computer unit's main body, dismounting a battery, removal of a memory board from the computer unit's main body or the like, the CPU saves system data no matter whether or not the resume mode is on and turns off the main power supply. Subsequently when the power switch is turned on the CPU checking if said system data is saved. The CPU restores said system data and restarts the data processing in case where the preservation of said system data is detected.

Abstract: In a battery-driven computer system, a flip-flop circuit selects one of two switches for switching a power supply to the computer system in accordance with the terminal voltages of batteries detected by detecting circuits. When the first switch is switched on, the first battery coupled to the first switch supplies its power to the computer system. In this case, the second switch is switched off and the power from the second battery coupled to the second switch is not supplied to the computer system. When the terminal voltage of the first battgnal representing the power condition of the batteries.