Abstract: The present invention relates to a method for managing the stack of a microprocessor comprising a central processing unit and a memory array, the central processing unit comprising registers containing contextual data and a stack pointer, the stack being a zone of the memory array used for saving contextual data upon a switch from a first to a second program. According to the present invention, the method comprises saving contextual data contained in a variable number of registers that varies according to the value of at least one flag stored in a register to be saved. Advantages: optimization of the filling of the stack and of the number of subprograms that can be interleaved.

Abstract: A programmable clock generator delivers, using a primary clock signal of determined frequency, a first clock signal the frequency of which is equal to the frequency of the primary clock signal divided by a set point M. The set point M is a decimal number comprising a whole part M1 and a decimal part M2 and the clock generator modulates the period of the pulses of the first clock signal so that the duration of Ni successive pulses is substantially equal to M*Ni times the period of the primary clock signal, Ni being a reference number for modulating the period of the pulses of the first clock signal.

Abstract: A system is provided for controlling access to protected data. The system includes storage means, protection means, an internal key, and means for receiving an input key from the outside. The storage means includes a protected zone for storing the protected data, and a command input for denying or authorising access to the protected data. The protection means controls access to the protected data by selectively activating the command input of the memory. The protection means authorises access to the protected data only when the internal key and the input key are identical. Also provided is a method for controlling access to protected data stored in a protected zone of a storage means. According to the method, an input key is received from the outside, and access to the protected data is authorised only when the input key and an internal are identical.

Abstract: An operational amplifier is provided that includes an inverting input channel, a non-inverting input channel, and an output stage. Each of the input channels controls at least one input transistor, and the output stage supplies an output voltage as a function of a potential difference at the input channels. Additionally, the operational amplifier includes at least one signal correction element in association with at least one of the input channels. The signal correction element is selectively put into circuit to selectively add an offset voltage correction signal to a signal that is supplied to the output stage in order to balance the characteristics of the two input channels. Also provided is a circuit for correcting the offset voltage of an operational amplifier.