|HP-15C, and the improvement over the HP-11C|
Message #10 Posted by Karl Schneider on 2 Aug 2009, 3:28 a.m.,
in response to message #7 by Katie Wasserman
However, if you ignore the features on the 15C that the 11C does not have (matrix operations, complex math, etc.) the only usability differences are that most of the tests (x<0, etc.) on the 15C have to be looked up on the back of the calculator. All of the un-shifted and most of the shifted functions are assigned to the same keys on both calculators.
Hi, Katie --
Yes, that's exactly right. H-P actually managed to slightly improve the arrangment of functions on the keyboard of the HP-15C over the HP-11C, even as four major elements of functionality were added using the same keyboard. Great thinking and engineering!
The broad set of functions on the on the HP-15C required intelligent use of two-byte operation codes where necessary. (The HP-11C and HP-34C used only one-byte keycodes, which explains why some reasonable functions were curiously missing from each.)
A thread from 2006 with many contributors:
HP-34C/11C instruction codes (corrected)
Essentially, when the HP-15C was introduced, the fine HP-11C was eclipsed, superseded, and supplanted, except maybe to occupy a price niche.
Here's a detailed discussion from three years ago:
HP-15C functionality and keyboard layout
Edited: 2 Aug 2009, 3:42 a.m.