Abstract: Optical transceiver (22) for calculator-to-calculator or calculator-to-module communication. The transceiver (22) includes an IR transmitter (24) and IR receiver (26) designed for use in the low power, low cost environment of calculators and portable computing devices. The transceiver may be adapted to communicate with the CPU (central processing unit (14) of a calculator (90) directly or with that of a portable computing device via its serial port (43). Devices in which the optical transceiver may be incorporated include calculators, plugless modules, and books containing plugless modules. Data such as mathematical formulas within the book may be stored in the associated module and transferred instantaneously and accurately to an adjacent calculator upon request by the calculator.