In the introduction of his book "HP-28 Insights", Dr. William C. Wickes (one
of the developers of the HP-28 and HP 48) gave the definitive answer to your
The HP-28 "language", which includes the operating logic as
well as the specific command set, is called <i>RPL</i>.
Computer languages are known for their whimsical names; RPL is
no exception--it stands for <i>Reverse Polish Lisp</i>. This
name suggests the HP-28's derivation from HP calculators (and
from FORTH, another language that uses reverse Polish logic)
and from the computer language LISP, which is frequently used
in computer symbolic mathematics systems. Note that the HP-41
language was never given a name, so many people call HP-41
programming 'RPN' programming,' which is unfortunate since,
properly speaking, RPN is a mathematical logic that is not
specific to any calculator or computer.
I would add a few comments regarding the HP-41 language. Sometimes it was
referred to as "user code" (as opposed to microcode). Some people tried to
establish the name "FOCAL" for it. I don't remember what it stood for. It
seemed an unfortunate choice to me as it bore no resemblance to the earlier
FOCAL computer language which was commonly available on minicomputers in the
60s and 70s.
The language name FOCAL on the beloved HP-41 stands for
FOrty-one CAlculator Language, simply.
__ __ _____ _ __ __ ___ | Henrik Koberstein
/ /_/ // ___// |/ // /__ / _ \ | Ericsson Radio Systems
/ __ // _/_ / // _// // / | CME20 OSS/CME40 OSS Management
/_/ /_//____//_/|_//_/\_\ \___/ | era...@lmera.ericsson.se
Fourty-One CAlculator Language? That's what I've heard...