These programs (exp6, anq6, cl6, antipa.cpp, antipa.h, antipb.cpp, antipb.h, antip20.h) are free software; you can redistribute them and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
These programs are distributed in the hope that they will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
A copy of the GNU General Public License is included in the bundle of code. A copy can be obtained from the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307,USA, or from the GNU licenses' page.
There are a few programs for the Palm but they are both non-free (free in the sense of free software) and very expensive. For both philosophical reasons and economical ones I would not consider these. Things are pretty much the same for the Pocket PC.
After a quick search in Google I found a product called "Outdoor explorer", for the Palm, that not only sells for the very affordable price of about 800 € (euro), but is, again, non-free software. Another non-free program is distributed by Pendragon software and sells for about $ 200. A product from Educational Consultingfor the Windows CE operating system for Pocket PCs sells for about $ 150 (so on top of being non-free and the price, you add Windows…). Sure enough, "The Observer", from Noldus, with a long reputation in behavioral research, has been ported to Windows CE handhelds. I mention all of these for the sake of completeness, but I would not consider any of these programs for my own work; there are philosophical reasons and many of them, in particular for grad students, carry quite a price tag (i.e., there are economical reasons). In addition, I don't think most of those programs would have worked for a situation like mine. Finally, writing or customizing the code (and customization is only an option with free or open source code or with code you write yourself) was, for me, an important part of thinking clearly and throughly about what, how, and why I was trying to measure.
An interesting approach is the one documented by Jeff Mudday's embedded systems for biological research page, also shown in the handheld computers presentation. If I were to start, I would surely check all this more thoroughly. On top of that, I have heard that programming the Palm is not that hard (there is plenty of documentation from both the Palm OS site, and several books out there) so it would be possible to roll your own code, though it might not be as easy as programming for the HP 48 (which was easy).
An interesting alternative would be the PocketPC: there are several ports of GNU/Linux, in different stages, for the PocketPC, and one of them, Familiar, comes with a full Python. This would probably be the way to go for me now. With Python, and without the constraints in size of files, I could write the programs to record the behavior and then comfortably edit the output at the end of the trial. This would also make things a lot easier, because I could write, run, test, and debug the code on a laptop before checking it on the handheld. Note, however, that I am not sure that, for situations such as mine, a Pocket PC or Palm would work well: I made use of a whole bunch of different keys in the HP 48 when recording behavior. So at least it would probably be necessary to use an external portable keyboard (I think there are inexpensive ones, starting at around 20 euro).
Finally, I don't want to end without a mention to Etholog, a very nice gratis program. I haven't found much about current development, but if source code were available, it might be possible to make it run under Windows CE, or even port it to GNU/Linux. My old link to Etholog no longer seems to work. A quick Google search yields the following link to download etholog.
These were written using the Borland IDE. They use some deprecated style, for example, for inclusion of header files, etc. But they at least compile without errors (only the warning about the header) under GNU/Linux, using g++ (version 3.3, as of this writing). [Today, I'd probably write this part with Python instead of C++; at that time, however, I new nothing about Python, and I wanted to learn C++, so this looked like a good training opportunity.]
The programs that were used for the experiments cited are antipa.cpp and antipb.cpp (and their corresponding header files). However, I also include antip20.h, because it defines several classes and methods that would be used to process the focal data, and obtain frequency of displays and other behaviors.longer explanation. They were written using a text editor on a computer, and then transferred to the HP, were they were tested. Probably an easier way to do some of this today would be to use an HP 48 emulator (there is at least one, I think, for GNU/Linux). The programs are written in "user RPL", as it used to be called in the newsgroups, as opposed to "system RPL". User RPL is a relatively simple lisp-like language, and the information contained in the "Advanced Users Reference Manual" (you might be able to find pdf versions in the web) is all you need to write programs. BehHP48.tar.gz is a compressed tar.gz file that contains the code for the HP 48 programs, the source code for the C++ files, the documentation, and this file.