Abstract: A keyboard-programmable electronic computer utilizes a user-accessible table located in memory to allow the user to list memory addresses to be associated with various key codes corresponding to keys on the keyboard. When a key is depressed upon the keyboard, the computer checks the table for the corresponding key code and, if it is listed therein, the user-written subroutine located in memory at the address associated with the key code is performed. The user-written subroutine has the capability of utilizing both the events of key depression and the status of continued key depressions as program variables.

Abstract: A piezoelectrically driven ink jet print head for ejecting ink droplets from an ink supply within the print head through a discharge channel onto a writing surface includes a shutter mechanism that may be electromechanically controlled during selected periods of time to seal the ink supply within the print head from the atmosphere and from a high speed laminar flow of air used to accelerate ejected ink droplets.

Abstract: A linear regulated D.C. power supply includes two control elements for regulating two separate unregulated D.C. voltage sources. An enabling means is used to enable the one of the two control elements which is operating at the lower instantaneous power dissipation level and to supply the regulated output of that selected control element to a load.

Abstract: An apparatus and method are provided to obtain a sharp index pulse with minium side lobes for an optical shaft encoder. By nonuniformly aligned multiple transmissive sections in the encoder wheel and phase plate of the shaft encoder, the transmissive sections become nonprogressively coincident in the light modulation process to provide the desired index pulse. In another preferred embodiment, secondary tracks having nonuniformly positioned multiple transmissive sections provide a parallel modulated light to enhance the index pulse and further reduce side lobes.

Abstract: The present invention is related to bus extender circuitry for data transmission from a first bus at a first site to a second bus at a second site, includes a first transceiver at the first site, a second transceiver at the second site and a data and control signals transmission medium interconnecting both transceivers. The first transceiver receives data signals and interacts by means of control signals with the first bus which has data and control lines connected to a data source and possibly also to one or more receivers all located at the first site. The second transceiver receives data signals and interacts, by means of control signals, with the first transceiver to transmit data and control signals to the second bus; the second transceiver has data and control lines connected to one or more receivers at the second site.

Abstract: An initialization routine provides to a CPU an instruction to be executed and multiple words of input data to be processed by the instruction. The CPU stores the input data in consecutive locations of a register having a boundary after the last word of stored input data. The CPU executes the instruction on each word of input data in sequence until the boundary is reached and the results are combined to form one word of processed data.

Abstract: An optical switch having low insertion loss and low crosstalk is provided by two slabs of birefringent material having a polarization rotator as a control element interposed therebetween. By controlling the polarization rotator electrically, a selectable ratio of transmitted-to-displaced output optical power is realized. The optical switch therefore can function as an attenuator to a light beam traversing through it. In the preferred embodiment calcite crystals are used for the slabs, and a liquid crystal cell for the polarization rotator.

Abstract: An apparatus is disclosed for determining the impedance and dissipation factor of a capacitive and/or inductive device and to reduce measurement error by digital calculation and manipulation. A synchronous rectifying means, a phase shifter and a detecting means are employed to detect the in-phase and orthogonal components of the current through a device and to compare it to a reference voltage impressed across the device. An arithmetical calculation using the values of these components determines the impedance and the dissipation factor of the device.

Abstract: An apparatus for solvent degassing and solvent supply in a liquid chromatograph comprises at least one solvent storage vessel, the volume of which is partly filled with liquid solvent while the remaining volume forms a vapor volume. A helium source is connected to said vapor volume for avoiding re-absorption of air by the solvent. A vacuum pump is connected to said vapor volume via a suction line, and a solvent source is connected to said vapor volume via a supply line. A pore filter terminates said supply line within said vapor volume.

Abstract: The electrical drive pulse applied to the piezoelectric crystal of an ink jet printer is designed to cause ejection of a single desired ink droplet from the print head and to preclude ejection of unwanted multiple ink droplets. The drive pulse consists of the superposition of two waveforms wherein the first waveform causes ejection of the desired ink droplet and the superimposed second waveform removes energy from the print head so that mechanical ringing of the ink supply within the print head does not cause ejection of unwanted ink droplets.

Abstract: A piezoelectrically driven ink jet printer includes a shock absorbing mechanism positioned in the ink supply tube for minimizing the effects on the ink within the print head of physical shocks to the ink supply tube or ink supply cartridge. The shock absorbing mechanism includes a flow restriction device and a reservoir device arranged such that the physical performance of the shock absorbing mechanism is analogous to the electrical performance of an RC low pass filter.

Abstract: A thermal printer employs a soft platen to enhance the quality of the printed results. The increased friction between the paper and the soft platen is overcome by interposing between the platen and the paper a flexible platen cover of Teflon.sup.R impregnated fiber glass fabric. The cover serves as a low friction barrier and also aids automatic loading of paper by funneling the advancing edge of the paper past obstructions in the paper path.