Abstract: The present invention provides a process for loading an off-board program into a computer peripheral apparatus connected to a host computer via a standard interface port. Random access memory of the peripheral apparatus is used by the host computer. The process includes the steps of: applying power to the apparatus, initializing the apparatus to achieve minimal operational conditions, polling the interface port for a signal indicative of a host computer to peripheral apparatus program download request. Upon receiving the download request, the peripheral apparatus configures the random access memory to receive the program via the interface port, then provides a signal indicative of readiness to receive the program. The program can then be downloaded from the host, received in the random access memory, and run. If the download request is not recognized, the apparatus is fully initialized to its normal state of readiness for receiving common commands from the host computer.

Abstract: An adaptive method allocates RAM between procedures having both higher and lower priorities. The RAM is provided with first and second portions, the first portion for assignment to higher priority procedures and the second portion for assignment to lower priority procedures, higher priority procedures being able to access also the second portion of RAM. The adaptive method comprises the steps of: responding to a request for allocation of RAM to a higher priority procedure by determining if RAM is available from the first portion and, if not, allocating RAM from the second portion to the higher priority procedure. The method enables allocation of RAM from the second portion to a lower priority procedure when available RAM in the first portion exceeds a first threshold level.

Abstract: The pulse-width modulated motor speed control circuit described herein includes a binary latch-controlled motor driver, wherein the state of the controlling match is determined by the phase of the drive signal and the level of back emf of the motor when the motor is not being driven.

Abstract: Two battery-powered hand-held programmable calculators for performing arithmetic, trigonometric and logarithmic functions and displaying the results thereof are provided with the capability of being fully programmable via magnetic cards or a keyboard. Through a unique transmographic coding scheme, programs coded on one embodiment may be executed on a second embodiment even though the key codes for the respective functions are dissimilar. In one embodiment, a processor distinguishes between magnetic cards containing coded instructions and cards containing data. The calculator prompts the user via the display when additional cards are needed to form a complete set of program instructions. The processor, registers, and display may be initialized by control words on magnetic cards. During program execution, the calculator can pause to permit data entry from the keyboard or from magnetic cards. The operator may also cause the calculator to pause and display the data of an intermediate calculation.