Abstract: A method for managing a power control system of a PDA (personal digital assistant) with a microprocessor. The PDA includes a CPU (central processing unit) for processing data and a microprocessor for controlling power control system functions including: switching the PDA from OFF mode to SHUTDOWN mode, such that when the PDA is in OFF mode, the CPU and the microprocessor are both off, and when the PDA is in SHUTDOWN mode, the CPU is off while the microprocessor is on; switching the PDA from SHUTDOWN mode to ON mode, such that when the PDA is in ON mode, the CPU and the microprocessor are both on; and, switching the PDA between SHUTDOWN mode and STANDBY mode, such that when the PDA is in STANDBY mode, the CPU idles and the microprocessor sleeps.

Abstract: A control system is used for determining a rotational direction of a ratchet that will output a pair of digital signals. The control system includes a microprocessor and a memory. The microprocessor is electrically connected to the ratchet for receiving the pair of digital signals. Afterwards, the microprocessor will compare the pair of digital signals with the previously stored pair of digital signals to determine if a conditional signal for determining the rotational direction of a ratchet is transmitted to a CPU or not. The memory is electrically connected to the microprocessor for storing the pair of digital signals.

Abstract: A method for managing a power control system of a PDA with a microprocessor. The PDA includes a CPU for processing data and a microprocessor for controlling the power control system. The method includes: (a) using the microprocessor to switch the PDA from OFF mode to SHUTDOWN mode, such that when the PDA is in OFF mode, the CPU and the microprocessor are both off, and when the PDA is in SHUTDOWN mode, the CPU is off while the microprocessor is on; (b) after step (a), using the microprocessor to switch the PDA from SHUTDOWN mode to ON mode, such that when the PDA is in ON mode, the CPU and the microprocessor are both on; (c) after step (b), using the microprocessor to switch the PDA between SHUTDOWN mode and STANDBY mode, such that when the PDA is in STANDBY mode, the CPU idles and the microprocessor sleeps.