From The Hewlett-Packard Personal Calculator Digest, Volume two, 1977,
pg 6:

"To really make it (the pocket calculator) useful in other areas where
larger calculators and computers are used, it should handle alphabetic
characters as well." (Some three years or so before the HP 41C)

More impressively, later on the same page:

"A calculator with alphabetic capability can, in principle, do
symbolic mathematics as well as numeric calculations. It is not out of
the question, indeed it is probable, that portable machines having the
ability to do algebraic problems and even symbolic calculus will be
available before the end of the century. When this happens an even
more drastic change will occur in the teaching of mathematics. Again,
the need will arise to distinguish between the learning and the
principles being learned and to emphasize the latter."

[Submitted by Michael Woodhams, Sun Jul 14 1991]