This was not a complex programming issue, but I appreciate your time in addressing it and hope that it helps at least one future newbie from having this same perplexing problem.

Changing the header comment might help to ward off the inexperienced user.  Making the wording even more stern might be good.

Something like:

## This file should only be used to configure the behavior of line-input editing for all
## Octave users when Octave is configured to use the GNU Readline library for input-line editing.
## 
## This file is NOT an Octave script for adding commands to the octaverc startup file.
##
## Please do not make changes to this file unless you know how
## GNU Readline configuration works.

Thanks for the quick response to my problem.

1. Does the problem not show up with a command window
docked to the main window?

The problem persists even when the command window is
docked to the main window.


2. Do you have some readline configuration in the .octaverc file?

OK.  This lead to the solution for fixing the problem:

Under the new Octave 5.1.0 installation under Windows 7, the following are the paths created for system configuration files:

  D:\Octave\Octave-5.1.0.0\ming64\share\octave\site\m\startup\octaverc

And, also the following paths:

  D:\Octave\Octave-5.1.0.0\ming64\share\octave\5.1.0\m\startup\octaverc
with the accompanying path
  D:\Octave\Octave-5.1.0.0\ming64\share\octave\5.1.0\m\startup\inputrc

(NOTE:  Under Octave 4.4.0, the path to octaverc did not have the additional  "\ming64\"  directory level.)
 
In the "5.1.0\m\startup" path, in the octaverc file, I saw the following comment:

## Re-read user's personal inputrc to give precedence over Octave's default.

So, I thought this was a good way to place user input in a convenient place for adding to the startup process without having to change the octaverc file itself.

So, that was the problem.  With the following lines added to the "inputrc" file:

addpath('D:\\OCTAVE\\GeoGraphs\\Georgia\\');
pkg load io
pkg load geometry
pkg load mapping
warning ('off', 'Octave:data-file-in-path');

You get the strange a/p/w input problems.  (Why?  I'll leave that problem alone.)

Removing those lines and everything goes back to normal.  I now see that the "inputrc" file is only  intended for user configuration relative to the GNU Readline library.

I also found that adding my startup commands to either one of the octaverc files (different paths) seems to work (without having to change the OCTAVE_VERSION_INITFILE environment variable).

So, I'm back to placing my startup commands into the octaverc file here:
  D:\Octave\Octave-5.1.0.0\ming64\share\octave\site\m\startup\octaverc
 
and, getting back to my real machine learning programming projects.

Thanks for the suggestions that lead me to finding the solution.

This problem can be closed for my purposes.

(By the way, when initially invoked, the new 5.1.0 version starts up much faster!)

My original submission seems to have lost the full description of the problem as I submitted it.  When typing "pkg load mapping", Octave reflects "kg lod ming" and signals an error.  When I use the function kbhit(), my input of "a" is accepted and returned as the proper answer (ans = a). Even when I enter "pkg load mapping" in the editor window, copy it and paste it into the command window, it is converted to "kg lod ming".  Something strange is going on with Octave accepting a/p/w directly in the command window.  By the way, it accepts the capital entry of those letters (A/P/W).

This works correctly (obviously) on this system using Octave version 4.4.0.