The Commodore F4902 calculator, introduced in 1978, is a cool example of the technological advancements in personal computing devices of its era. Manufactured by Commodore in Hong Kong, this calculator is known for its extensive range of functions and unique design features.
The F4902 is encased in a two-piece stippled black plastic shell with silver printed trim, giving it a sleek yet functional appearance. The brand name, “Commodore,” is raised and printed in silver, although the durability of this printing has varied over time. The keys are arranged in light and dark grey, white, and black, with raised additional labels printed in silver on the keyboard surround. The keys themselves are of the short travel, squishy type but are noted for their effective responsiveness. The display is heavily inset and tilted, featuring a red filter that enhances visibility, resulting in a large, bright display.
The F4902 calculator measures approximately 80mm in width, 147mm in height, and varies between 20mm to 40mm in depth. It weighs 124 grams, excluding batteries, making it relatively lightweight and portable. The calculator is powered by a 9V DC PP3 size battery, with an option for an adaptor/charger located on the top side. Compatible adapters include the DC-505, 707, 708, or 709 models. Additionally, the F4902 includes a power-save function that turns off the display after a period of inactivity.
The display of the F4902 is an 11-digit red LED with a bubble lens, featuring a twelfth digit for negative, error, and statistical indications. This design allows for clear and precise readings, essential for complex calculations.
The F4902 offers an impressive array of features, including four basic functions, percentages, delta percentages, change sign, register exchange, powers, square root, reciprocal, brackets, nth root, squares, logs, and a variety of statistical and financial functions. It also includes a four-function memory, enhancing its utility for advanced calculations.
Internally, the F4902 is powered by a single CPU, the MOS M867561, a 28-pin DIL chip. The calculator’s construction is straightforward, with a single board serving as both the keyboard and the main CPU board. This board is secured to the front by six screws, and the back section can be easily removed by unscrewing two long screws from the rear.
Logic:
- The (C/CE) key cancels the last number entered and clears the entire calculator with a second press.
- There is no constant function available.
- Input overflow is suppressed; entering a twelfth digit is ignored.
- Negative numbers are displayed with a “-” in the far left (thirteenth) digit.
- Dividing by zero results in a display of zero with no error message, allowing calculations to continue.
- Overflow results in no number being displayed, with an “E” in the left (twelfth) digit, and is not recoverable.
- Negative square roots result in no display and an “E” in the left (twelfth) digit, also not recoverable.
- The change sign function can be used mid-number entry.
- Memory storage is not indicated on the display.
- It is possible to store an error state in memory.
- A power-save function turns off the display after about 60 seconds, showing a single decimal point in the first digit (except in error conditions where nothing is displayed).
- The (F) key selects the operation labeled above it.
- Financial keys include (N) for the number of periods/payments, (i) for interest rate, (PMT) for payment, (PV) for present value, (FV) for future value, (CST) for cost price, (SEL) for selling price, (MRG) for margin, (SLP) for slope, (INT) for intercept, (X hat) and (y hat) for predicted values, (DLT) for entry delete, (Xi) and (Yi) for data entry keys, (x bar) for sample mean, (S) and (S’) for standard deviation, (CFL) for cash flow, and (O/D) for ordinary/annuity due switch.
The Commodore F4902 calculator is a robust and feature-rich device from the late 1970s. Its design, while functional, includes some quirks such as the lack of constant functions and error recovery features. Despite these limitations, the F4902 remains a great example of the advancements in calculator technology during its time, offering a wide range of mathematical and financial functions that catered to both general and specialized users.
