Instruction manual for the SONY SOBAX ICC-2500E programmable desktop calculator. ‘SOBAX’ is derived from ‘Solid State Abacus’. The manual covers ordinary calculations, memory functions, programming and practical applications in business, research and engineering. The calculator uses bipolar integrated circuits and has a 15-digit numerical display. It performs addition, subtraction, multiplication, division and square roots. Other controls support sign changes, repeated calculations, recalling or reversing operands, adjustable decimal positioning, rounding and truncation. A separate total register accumulates results. Its seven numerical memory registers store and accumulate values for later use. Program capacity reaches 111 steps: the first 63 use dedicated program storage, while longer programs progressively occupy numerical memories 7, 6 and 5. At maximum program length, four numerical memories remain available. Programs are entered through the keyboard in LEARN mode, either while performing an example calculation or by entering the operation sequence directly. The calculator can then repeat the procedure with new input values. A Start-Stop key pauses execution for data entry or inspection of intermediate results. CHECK mode displays instructions individually, allowing users to identify errors, correct individual steps and replace sections. The Jump key provides conditional branching and loops, enabling programs to repeat calculations or choose between alternative procedures according to a result’s sign. Worked examples include triangle areas, Fahrenheit-to-Celsius conversion, hypotenuse calculations, simple and compound interest, variable discounts and iterative cube-root extraction. The specifications lists maximum power consumption of 32 W, and an operating temperature range of 0–40°C. Listed calculation times are 0.04 seconds for addition or subtraction, 0.25 seconds for multiplication, and 0.4 seconds for division or square roots. The manual also explains overflow indications, correction of entry errors, power requirements and care of the machine. Switching off clears all stored data and programs. Supplied accessories include a dust cover, polishing cloth, power cord and adjustable display hood.