Abstract: A circuit for detecting the failure of a step motor to respond to energization commands, which takes advantage of the time constant decrease of an energized phase which occurs due to stalling of the motor. A predetermined current level I in the energized phase is reached in a time interval TI which is shorter than a time interval TO necessary to reach the same current level when there is a response of the motor. The circuit comprises a timer having a predetermined period between TI and TO which activates a bistable circuit indicative of a failure to respond if the current level I is reached in a time shorter than the required time period.

Abstract: A sheet front loading printer comprising a printer body with a chute beneath the body and having the inner portion bent upwards in order to guide a sheet inserted therein up to the platen. The platen also doubles as a sheet feeding device. To allow the use of sheets having a dimension less than the one defined by the path of the bottom of the chute, the chute is provided with at least one elongated opening or indentation and an arrangement of the printer supports which allows the printer to rest on a working plane. This permits further advancement of the sheet by manual action performed by the operator through the opening in the bottom of the chute.

Abstract: Rack housing for user reconfigurable EDP system comprised of a frame frontally opened to allow the insertion of a plurality of printed wired artworks (PWA) each one in a rack position. A protection ruler fixed, with the aid of tools, to the open frame front prevents the extraction from the frame of the PWA constituting a basic EDP configuration. Substitution of optional PWAs into the system via selected rack positions is accomplished by suitable undercuttings selectively arranged on the projecting edge, and by one or more panels covering the open front and removably fixed. Each panel is easily removable without need of any tool, so that the protection ruler is positioned between frame and cover panel (or panels) and cannot be removed without the previous removal of the cover panel (or panels).

Abstract: A high quality printing method utilizing a matrix serial printer having a print head provided with needles arranged in a vertical column. The method comprises the steps of printing a print line in two print passes, and in advancing a platen, between the first and the second pass, by an amount equal to one and a half times the vertical pitch, center to center, between two contiguous needles.

Abstract: In a data processing system wherein a memory is comprised of an unknown plurality of memory blocks of a basic capacity, arranged in an unknown plurality of modules which have an unknown capacity multiple of the basic capacity, a method addresses the memory location which involves the selection of the module containing such locations by use of a directory having a plurality of addressable locations.

Abstract: A cooling apparatus for a dot matrix impact print head suitable for application in serial printers. The print head is mounted on a carriage sliding on guide bars for reciprocating movement thereon. A liquid filled container having an inlet and outlet is mounted on the carriage and is in thermal contact with the printing head. A heat dissipator also mounted on the printer has a liquid filled cavity with inlet and outlet with flexible conduits connected to the inlets and outlets so as to form a liquid circulation loop. A unidirectional fluid valve in said loop maintains liquid circulation in the loop by the reciprocating movement of the liquid container.In the preferred form of embodiment the liquid container is formed integral with the print head, the liquid in the container being in direct contact with electromagnetic cores of the print head, and the heat dissipator is formed by a guiding bar, the bar being hollow and having an inlet and outlet.

Abstract: A memory module selection and reconfiguration apparatus in a data processing system wherein a modular working memory formed by a plurality of memory modules sends to a central processing unit information related to the capacities of the constituting modules (M1, M2, M3, M4) during the system initialization. The central unit processes such information and provides memory, via a channel (30), with information representative of the capacity of the first modules (G1), of the sum of the capacities of the first and second module (G2), of the sum of the capacities of the first, second and third module (G3) and so on, up to the total capacity of the working memory. This information is stored into registers (31, 32), each one related to a possible module, of a module selection unit included inside the working memory.

Abstract: A step motor driving circuit, wherein the motor has two pairs of magnetically coupled windings (1, 2 and 3, 4) and includes switching transistors (9, 10, 11, 12) associated to the windings, diodes (15, 16, 17, 18) in parallel to the switching transistors for the recycle of the current induced during the possible current chopping and the phase switching, and a diode (6-8) and a capacitor (5-7), in parallel to each other and series connected between the voltage source, and each pair of magnetically coupled windings. When a phase is de-energized, the driving circuit allows the recovery of the energy stored in such phase by charging the capacitor coupled to it. From such capacitor the energy is then returned to the phase magnetically coupled to the previous one in case of phase switching or to the same phase in case of current chopping. The driving circuit speeds up the phase switching and therefore increases the torque delivered by the motor at high frequencies.

Abstract: Serial printer provided with cutter, the printer being of the type in which printing is performed by a printing head mounted on a carriage sliding on guides parallel to the printing line and a continuous printing support moves perpendicularly to the direction of such guides leaning against a substantially vertical platen. A rotating cutter is lever-mounted on the carriage over the printing head in a position very close to the printing line and it can be actuated in order to partially overlap a cutting edge of the platen, the edge being parallel to the printing line.Owing to the printing head movement along the printing line, the rotating cutter when actuated operates the transversal cutting of the continuous form. The cut form is disposed in a collecting drawer behind the platen owing to the movement imposed by the rotating cutter and to the reduced thickness of the platen which constitutes a drawer wall.

Abstract: Keyboard coding apparatus couples to a plurality of keys and comprises a scanning interface including a counter (23), a decoder (13) and a multiplexer (22). The scanning interface, in response to each pulse received from a microprocessor (1) through an input lead (11), sends to the microprocessor on an output lead (10) a logic signal indicative of the state of any selected one of the keys. Whenever microprocessor 1 sends a pulse to the scanning interface, it increments by one the contents of an internal register and, before sending another pulse, processes the signal from the scanning interface. When the logic level of such signal indicates a condition of an actuated key, the microprocessor waits a predetermined time interval to establish that said selected key activation is valid, then waits until the selected key has been deactivated and then accesses the character code related to the actuated key from a memory location whose address is latched into its internal register.

Abstract: An adjustable diameter pulley, particularly suitable for the belt tension adjustment in belt transmission system such as those used in serial printers, utilizing a central core having a tapered portion, a threaded cylindrical portion and also a plastic ring having external cylindrical surface and a central tapered opening. The opening receives the conical portion of the core and is provided with deep slits which allow its expansion. A second ring, screwed on the cylindrical portion of the core, causes the expansion of the plastic ring to vary.

Abstract: A stepping motor drive circuit having pairs of magnetically coupled phase windings (1, 3 and 2, 4), comprises current chopping control circuits (23, 24) for controlling the on/off switching of a plurality of driving transistors (5, 6, 7, 8) each coupled to a respective phase winding, and the circuits associated with each switching transistor for reducing their storage times and hence switching losses. More particularly, with reference to the switching transistor (5), the related circuit for storage time reduction comprises a series connected capacitor (25) and a diode (45). The circuit connects between one terminal of one winding (2) of the pair of phase windings which is magnetically coupled to the one winding (1) of the other pair connected to such switching transistor (5) and to the base of such transistor (5). As soon as the transistor (5) is caused to switch from ON to OFF, the circuit applies a reverse voltage pulse to the base of the transistor (5) causing a fast transition towards the cutoff region.

Abstract: An electromagnet assembly for a matrix printing head which can be automatically assembled and a manufacturing process for automatically assembly said electromagnet assembly.

Abstract: Step motor control circuit of the "current chopping" type where, according to the required operative conditions, both the energization current level and the "chopping" frequency is varied. When the current level applied to the motor phases is high, a relatively low chopping frequency is used and, on the contrary, when the current level is low a relatively high chopping frequency is used. Particularly, this allows the use of chopping ultrasonic frequency for the holding operative condition of the motor, where a low energization current level suffices, without causing unacceptable power losses in the current switching components. This has the advantage of eliminating under such condition, the motor noise due to the pulsating electrodynamic actions to which the motor is subjected.

Abstract: A serial printer is disclosed where the printing is performed by a printing head (22) mounted on a carriage (21) movable along the printing line, a transparent leaf (36) mounted on the carriage presses the printing support (25) (paper) against a platen (24) around the zone where the impression is performed thus considerably reducing the noise and vibration generated by the printing support vibrations during the printing.Preferably, the leaf is provided with a window (45) wherein the impression is performed in order to press the printing support against the platen all around the print zone. As the leaf is transparent, it does not preclude the visibility of what is printed. Besides, as the leaf is mounted on the carriage, when the carriage is in its travel position, the leaf does not interfere with the loading of the printing support in the printer.

Abstract: A system comprising interface circuits for coupling together for bidirectional information communication the various units of a data processing system, wherein such communication is effected by a totally interlocked bidirectional dialogue carried out over a single lead, but utilizing signals transmitted on another lead of the interface for clearing the interface circuits associated with the single lead.

Abstract: A method of symptom compression involves a symptom compression device receiving binary coded information including bits signifying symptoms present in the course of each operating cycle at selected points in an integrated logical network, microprocessor or the like. The device includes a first register, a second shift register, an EXCLUSIVE OR logic network, and a display. The binary coded information is received on parallel inputs of the first register and applied from parallel outputs of the first register to a set of inputs of the EXCLUSIVE OR network, a second set of inputs which is connected to at least some parallel outputs from the second shift register. A set of outputs from the EXCLUSIVE OR network is connected to parallel inputs of the second shift register. In each cycle, the bits in the second shift register, which accumulate information representative of symptoms, are shifted in one direction and are recirculated. The display is connected to the parallel outputs from the second shift register.

Abstract: An interrupt handling apparatus for a data processing system comprising a plurality of processing units and a working memory to which the units may access through a common bus by means of multilevel priority or access requests.Access requests are forwarded by each unit to a bus access controller preferably made part of the working memory through a single lead for each unit, irrespective of the access request priority level; and if the priority level of an access request is high, a high priority level access request signal is distributed by the high priority level interrupting unit to the other system units, which mask their possible access request of a lower priority level in response to such signal.The bus access controller grants access to a unit at a time on a priority basis determined by a priority network in the controller totally insensitive to any priority level difference of the access requests.

Abstract: A circuit for coupling together for bidirectional information communication pairs of devices of a digital data processing system, wherein such communication is effected by interlocked information signals, and wherein there is provided a single lead for the bidirectional transfer of such interlocked signals.

Abstract: An impact matrix printing head for use in a computer printer. The printing head utilizes a unique design to provide an unitary needle guiding assembly and an unitary electromagnet assembly which can each be independently removed from the printer head without the need to disassemble. The printer head includes adjustments for the air gap of the electromagnet assembly and adjustments for the needle position, both initially and after needle wear has occurred.