What is the primary selling point of the TX-78 calculator according to the advertisement?

The primary selling point of the TX-78 calculator, as highlighted in the advertisement, is its extensive memory and storage capacity. This is a significant selling feature because it directly addresses the needs of users who require a calculator that can handle complex calculations and store a large amount of data for later use. Effective memory and storage capabilities enhance productivity, making it suitable for students, professionals, and anyone needing to perform extensive calculations without the inconvenience of constantly re-entering data. Users can efficiently manage their mathematical tasks, resulting in a more seamless experience with the calculator.

Other features, while potentially attractive, do not serve as the primary focus of the advertisement. For instance, portability and design aspects are important but may not be as compelling as the practical functionality offered by extensive memory. Additionally, while advanced graphing capabilities and a unique color display might appeal to specific user groups, they do not fundamentally define the calculator's utility in the way that robust memory and storage do. Hence, the emphasis on these extensive features makes it clear that the TX-78 is tailored to meet serious computational needs effectively.