Abstract: A hand-held microcomputer-based ruler-like measuring and calculating instrument, particularly adapted for but not restricted to the graphic arts field, is capable of registering individual size measurements, proportioning successive readings in percent, converting to different units and visually displaying numeric results. The measuring, computing and indicating system has been human-engineered to eliminate fatigue and risk of error associated with conventional methods of repeatedly sizing and proportioning graphics elements. Distance along a fixed ruler scale, gaged by a slider-mounted pointer, is sensed and encoded electro-optically from an internal fixed bar-scale, digitally decoded, registered, processed and displayed. Optional audible indication enables the sliding pointer to be reset manually to a memory-stored reference point without eye contact, simplifying multiple sequential readings and proportioning factor determinations and thus greatly reducing mental and visual effort.

Abstract: An electronic security system for a device requiring an external power source is disclosed. The security system includes a microcomputer which executes a power-on routine stored in memory whenever the microcomputer is initially coupled to a power source. The user must enter a primary security code which is compared to a predetermined code, and if the codes match, the microcomputer signals a relay to provide power to the device, thereby enabling it. Once enabled, the user need not reenter the security code as long as the external source of power to the device remains uninterrupted. A secondary security code may be entered if the primary code has been forgotten or misplaced. Upon entry of the secondary code, the microcomputer displays an encrypted version of the primary security code. If an incorrect code is entered by the user, the microprocessor executes an alarm routine which may include visual and audible warnings.