Abstract: An ink cartridge for an ink management system includes a piston having a stepped back surface for improved reflection of ultrasonic acoustic waves through presentation of flat surfaces normal to the incident waves, thus permitting the piston to possess a preferred cone shape and structural rigidity. Heights of steps are preferably separated by even multiples of one-quarter wavelength of incident acoustic waves to avoid destructive interference from multiple reflections. Improved reflectivity overcomes problems with using an acoustic range finder to measure the position of the piston.

Abstract: An apparatus for use in a stand alone microcomputer controlled system having a digital memory device and a microprocessor unit includes a small battery supply and circuitry for sensing the power applied at the power terminals of the microprocessor unit and the digital memory device to control initial power application and power supply failure in a manner to prevent loss of volatile digital data. The memory power requirements in the power off or standby mode are approximately 1000 times less than in the operating mode thereby to permit volatile data to be stored in a volatile random access memory for a substantial time independent of system power. The monitoring circuitry includes circuitry for detecting the power levels, switching the power, disabling the memory device in the microprocessor, and for restarting the microprocessor once power has been restored.

Abstract: A method for inhibiting tampering with data on a magnetic stripe card is disclosed. The data are erased if the card is prematurely withdrawn from the reader/writer. A write protect bit is set and recorded on the card if the power source is interrupted. Apparatus for activating the tamper-proofing techniques are disclosed.

Abstract: Method and apparatus for registering selected new magnetic data on magnetic stripe cards for use in a vending machine account control system, such as is employed with a photocopy machine. Specifically, card author is provided which consists of a keyboard with data entry and operation control keys, keyboard scanning means, an input/output storage port and a bus connector which can be coupled directly to a duplicator controller. Upon connection of the card author to the duplicator controller, and with the duplicator controller in a card author mode, the duplicator controller initiates interactive operation with the card author in order to request certain information not normally accessible to manual manipulation as by a key operator. Through its display, the duplicator controller requests entry of at least three different types of values, a value representing worth of a card to be authored, an account number, and a delimiter value.