Abstract: The present invention relates to a method for dispatching at least one predetermined secret key, in order to make the implementation of a provision of service secure, characterized in that it comprises transmitting a predetermined implementation key in encoded form from a security module (MSCl) having a predetermined rank to a security module (MSTl) or card (U) of a rank lower than the predetermined rank, this encoding comprises using an encoding algorithm and introducing the predetermined implementation key, as well as least one diversified key, this diversified key, necessary for the encoding, being obtained by a diversification algorithm by introducing both a basic key of this diversified key and diversification data originating from the module of lower rank, the predetermined encoded implementation key being decoded by the use, in a module of lower rank than the predetermined rank, of a decoding algorithm which is the inverse of the encoding algorithm.

Abstract: A method of recording numerical information in a plurality of disk units, in which the bits of each word of numerical information are transmitted simultaneously, each bit being allocated to a unit associated with the weight of that bit in that word, and a memory system for implementing the method, including a main controller (2) provided with a selector enabling the distribution and synchronization of the information signals.

Abstract: A method of recording numerical information in a plurality of disk units, in which the bits of each word of numerical information are transmitted simultaneously, each bit being allocated to a unit associated with the weight of that bit in that word, and a memory system for implementing the method, including a main controller (2) provided with a selector enabling the distribution and synchronization of the information signals.

Abstract: A DC motor drives a magnetic disk memory transducer head between a position proximate the disk periphery to an area on the disk where data are located during which time the head is lowered from an idle to a hovering position. During this time the motor is supplied with a current impulse having a predetermined polarity, amplitude and duration. The polarity of the current impulse is opposite to that of current applied to the motor while the head is being driven between a position beyond the disk periphery to the position proximate the disk periphery. The duration and amplitude of the current impulse are such that the motor angular velocity has a zero value at the completion of the current pulse. Thereafter, a ramping voltage having an average linear waveform is applied to the motor to prevent overshoot of the motor speed and prevent oscillation of the head relative to a face of the disk. The linear ramp current decreases to a zero value, at which time the motor has a constant, non-zero angular velocity.

Abstract: A device and method for writing data on a magnetic medium (SMI) are disclosed for use in connection with a recording layer (CMI1) made from an anisotropic material having the axis of easy magnetization perpendicular to its surface and which moves past at least one magnetic writing transducer (TMI). According to the invention, this device is characterized by the fact that the transducer comprises two adjoining writing poles (PEI1, PEI2) having opposite polarities and supplying simultaneously, in a direction (Oz) parallel to the surface of the layer and perpendicular to the base material's direction of motion, magnetic writing fields (Hy) which are normal to the surface of the layer with opposite polarity. The device is particularly applicable for writing data on a magnetic disc adapted for opto-electronic readout.

Abstract: A magnetic disk memory is moved between a first position beyond the disk periphery to a second position proximate the disk periphery while the head is at an idle height above the disk face. The head is moved between the disk periphery and a third position at the edge of an area on the disk where data are located while the head is lowered and raised between the idle height and a hovering height above a face of the disk. An assembly carrying the head includes a radially extending arm, turned by a rotary DC motor. A continuous step excitation waveform is supplied to the motor as the head is driven between the first and second positions until the head arrives at one of the two positions. Each of the steps has a constant amplitude that differs from the immediately preceding step by a predetermined incremental value. All of the steps, except the last step, has the same predetermined duration.

Abstract: The invention relates to a method and a device for protecting software delivered to a user by a supplier. The method amounts to rendering the programs non-executable in the state in which they have been delivered to the users. With each program (P.sub.i) there is associated a validation key defined via a main validation key (V.sub.i) delivered by the supplier and recorded in a storage area (M) of the user's machine (1), and via a supplementary key (V'.sub.i) computed on the lever of a card (C) issued to the user via a secret code (S) and via arguments (b.sub.i) that identify each program (P.sub.i) and are recorded in a storage area (M1) of the card (C).

Abstract: A multilayer magnetic recording medium including at least one magnetic layer (CMOI) formed of an alloy including one of the group of heavy rare earths and a metal of the group of the first series of transition metals surrounded by at least two dielectric layers.According to the invention, the magnetic medium is characterized in that it includes means for preventing the diminution of the number of atoms of rare earth participating in the magnetism of the magnetic layer disposed on both sides of the magnetic layer.Applicable to magnetooptic disks.

Abstract: The invention relates to a printing apparatus of the type which transfers an image without impact. This apparatus includes a flexible recording tape (20), a printing block (28) which is displaced along the tape so as to record latent images onto it and deposit a powdered developer onto these images, the developer thus forming these images in powder. A press cylinder (53) enables the tape (20) to be pressed onto a print carrier (11), which assures the transfer of the powder images onto this carrier. The invention is applicable to the printing of data in a data processing system.

Abstract: The invention relates to a method and an apparatus for authorizing the holder of a portable object such as a card to gain access with this card to at least one service provided by at least one authorizing entity. According to the invention, the method enables the holder of a card C to become authorized to have access to a particular service by causing an authorizing datum to be written on his card C by an authorizing system T, causing the calculation by both the card C and the system of a result taking into account at least one secret datum S, comparing in a comparator CC of the card the results calculated, and validating the authorizing datum if the results are identical.

Abstract: A process and a device for authenticating the signature of a signed message includes a nominal signature card (1a) coupled to a transmitting device 1 which sends signed messages. The card (1a) includes at least one memory (5) in which there are secretly prerecorded at least one secret key (S) and one program (P) which automatically processes the signature of a message (M), as well as circuits (6) for computing the signature (SG). A control card (3b), which is not nominal, is coupled to a device (3) for receiving signed messages. The card (3b) includes at least one memory in which there are secretly prerecorded at least the secret key (S) and the program (P) for recomputing via processing circuits (15) the signature (SG) of the received message (M).

Abstract: The invention relates to a printing method and to a magnetic printing machine, which makes it possible to obtain images in at least two colors on a printing medium. A magnetic recording device (13) is arranged such that when it is excited by pulses it forms magnetized points on the drum (10). The points comprising elementary magnetic domains having magnetizations in different directions. The machine further includes developer applicators (40, 42), retouching devices (41, 43) and a transfer post (45), where the developers deposited onto the drum (10) are transferred onto a strip of paper (20).

Abstract: A disc of a magnetic disc cartridge is braked while the cartridge is outside of a receptacle of a magnetic disc memory unit by a radially extending leaf spring mounted on a wall of the cartridge so it has a free end engaging an aperture in a drive platter. The drive platter has an aperture that is engaged by a drive post of a drive disc connected to the memory drive shaft while the cartridge is inserted in the receptacle. The leaf spring is positioned so that the free end thereof is lifted out of the aperture by a post fixedly mounted on the memory unit to release the brake member while the cartridge is in place in the receptacle.

Abstract: In a system for the transmission of confidential data between a transmitter 1) and a receiver (3), the transmitter (1) transmits a standard key E to the receiver (3). The standard key E preferably is a random number generated within the transmitter (1). An element at the location of the transmitter (1) calculates an intrinsic key R.sub.1 for coding the data to be transmitted, and an element at the location of the receiver calculates an intrinsic key R.sub.2 for decoding the data. The calculation of each of the intrinsic keys R.sub.1 and R.sub.2 is accomplished in each case by a microprocessor (4' and 5') situated within a portable object (4 and 5) which also includes a memory (4" and 5") storing a program, a secret code S, and an identification code I.sub.n. The intrinsic keys R.sub.1 and R.sub.2 are each calculated as a function of the secret code S, the identification code I.sub.n, and the standard key E. The portable objects at the transmitter and receiver ends of the system must be matched.

Abstract: A magnetic disc in a cartridge is ventilated to keep a data containing surface portion thereof substantially free of particulate materials. A recirculating gas path includes apertured conduits for supplying gas jets completely across the portion as the disc is rotating in an enclosure. An orifice removes gas from the enclosure. A fan circulates the gas removed from the enclosure through the orifice and supplies the circulated gas back to the apertured conduits. Magnetic heads are positioned relative to the orifice and an inlet for the gas jets such that the gas has laminar flow as the gas passes the magnetic heads so the gas flow does not affect the position of the heads relative to the disc portion. The recirculating path includes filters for removing particulate materials from the recirculating gas.

Abstract: Optical apparatus (DISFOCI1 to DISFOCI4) for focusing a beam of light for reading of a data medium moving past it, comprising, a main body (CPLI1 to CPLI4) disposed to fly above the data medium and at least one optical device (OPFOCI1, OPFOCI2, OPFOCI3, OPFOCI4, OPFOCI5) for focusing of the beam, the optical device being located such that its distance in relation to said medium remains constant. The optical device is placed on the main body and is integral with the movement thereof. The apparatus is adpated for optical reading of magnetic optical data.

Abstract: Data are written as transitions on plural tracks of a magnetic disc by a transducer which travels along an arcuate curve formed by an arm turning about an axis beyond the disc periphery. Transition positions are defined by the phase thereof relative to that of a reference indicator on a track of the disc. To align the transitions along a predetermined arcuate curve, a reference transition having a reference phase is written onto a given track. Other transitions of the second curve are written with a phase shift relative to the reference phase.

Abstract: A transducer for writing data on a magnetic carrier includes a magnetic circuit having a writing pole piece (PPI.sub.2), realized in thin magnetic layers of anisotropic magnetic material. A conductor (CMPI) for controlling the writing is coupled magnetically with the pole piece and acts upon the pole piece for writing a datum by reversing the magnetization. A second control is magnetically coupled with the pole piece (PPI.sub.2), but does not act upon the pole piece except in the case of non-writing by diminishing the effective action of the conductor control.

Abstract: The invention relates to apparatus for clamping superimposed conductive elements (11, 13) disposed in aligned groups by means of a clip device (22, 23) such that an integrated circuit device may be removably connected to a printed circuit card with a predetermined force being applied uniformly across all the superimposed elements. In accordance with the invention, at least one of the clips (22, 23), in the free state, has a cambered form, equivalent to the elastic deformation of an initially straight beam of uniform section and of the same length mounted on two simple supports spaced this length and uniformly charged over this length.The invention is primarily used for the electrical interconnection of integrated circuit devices to printed circuit cards.

Abstract: The invention relates to an apparatus for developing latent magnetic images used for example in magnetic printing machines. This apparatus includes a retouching device (20) comprising, first, a transport roller (27) which is displaced in the direction opposite that of the magnetic recording surface (13) in proximity with which it is placed and, second, a magnet (31) disposed in the interior of the roller (27) in such a manner that facing this surface it has a pole (32) the polarity of which is opposite that of the magnetized zones (14) of this surface, the magnetic axis (N'S') of this magnet being inclined in the opposite direction from that of the displacement of the surface (13).