The Hewlett-Packard 71B is arguably one of the most potent pocket computers ever produced. However great this system was, it suffered several limitations, some by design! HP used one of these limitations by design as a selling point: buy the platform, and expand it as needed so that it could fit your computational needs. And indeed, this was true. One could easily spend the double of the base cost – already hefty –, in extensions. Fair enough, not everyone needed a FORTH/Assembler module.
But HP made a huge mistake according to many users: cram into the limited ROM space of the 71B a useless algebraic CALC mode – I would even call this a heresy – while relegating critical mathematical capabilities to a costly expansion module. The 32KB HP-82480A MATH module (5061-7226) cost ~$100 in 1985. Count several times this value today!! Think about this module as the equivalent of an HP-15C, one of the best scientific calculator of the time. I attached for your reference an article form the July 1984 edition of the Hewlett-Packard Journal.