Caveat: Most of the following discussion is focused on PalmOS PDAs. That is because I have a Palm PDA and because that is, quite frankly, mostly what I have found online so far. Where possible I will address non-PalmOS PDA issues. If you know of any pertinent information sources, or if you see mistakes in this article, please let me know.

First, I must admit that I have no special background that qualifies me to write anything about this topic. Heck, my PDA is an old Palm V which doesn't have enough memory to run a lot of the software that will be highlighted here. Nevertheless, I do have a longer-term interest in this topic and so I decided to do some intensive research. This article is my attempt to distill all that I learned as a result.

Writing in Japanese on an English Palm OS
Unless you buy your PDA in Japan, it will probably come with an English OS which means, especially for PalmOS, that you are probably unable to enter text in Japanese. Since having a dictionary or other Japanese study program will likely require this ability, getting it is the first order of business.

Later on we'll learn about popular programs like KDIC, Dokusha, Radic, etc. But to use these we'll want to probably install one of the following: �

• CJKOS or J-OS (Japanese OS)
  Both of these programs allow you to display/input Japanese characters on English version of Palm-OS. Neither program is free, though you can get a 30-day free trial of CJKOS at The Monash Nihongo ftp Archive and if you have an older version of Palm OS (3.3 or lower I think) you can use the free J-OS 1.9. You can download it at the Monash site as well.
  
  To use J-OS you MUST also install the ElisaL10 font
  
  Once I installed J-OS 1.9 I could see how it works. Basically, you use the HackMaster program (comes with the download if you don't already have it installed) to turn the J-OS program on and off. If it is on (checkbox selected) when you select the abc input method a popup screen appears and you can enter Japanese using romaji like you would if you were using a PC-based word processor.
  
  
• Treo Keyboard Utils
  I don't have a Treo so I haven't investigated this site too much but I think it might be similar to the above programs for the Treo. Or, it may just toggle between regular input and J-OS or other input methods (more likely I think). This would still be a nice feature though�
  
  
• POBox
  I think this is an IME (Input Method Editor) similar to J-OS and CJKOS. I also believe it is free and available for PalmOS 5. No English documentation is available.
  
  
• Manae
  This is another IME similar to J-OS etc. The manual page is actually written in English. I haven't tried this but it looks promising.
  
  
• GoGoPEN
  This is a separate palm-size writing tablet and software that lets you write kanji directly into your PDA.
  

Note that J-OS (I'm not sure about CJKOS) only allows kana input (kanji can be selected as is done in typical word processing programs). It's not clear to me if the programs that do allow kanji character handwriting recognition can replace J-OS/CJKOS or not.
Once you have that step out of the way, it is time to take the next logical step � finding dictionary software.

KDIC/KDIC DA
KDIC/KDIC DA is sort of universal dictionary software. Basically, it provides the foundation for various dictionary files that people can create to suit their needs (for example, a specialized medical dictionary, etc.). The best place to download this software is probably The Monash Nihongo ftp Archive.

KDIC vs. KDIC DA
DA stands for Desk Accessory. The point of KDIC DA is to allow you to use KDIC without actually having to exit your current application (e.g. memo pad) and running KDIC. You can imagine this would be very useful if you are reading something in Japanese and want to do a quick lookup. In order to get KDIC DA to work you need to install a DA Launcher, along with HackMaster, which you should already have installed with J-OS or from other applications that use it.

Apparently there are lots of DA Launchers but I downloaded LazyLauncher. Once installed and activated (via HackMaster) you can launch it by the standard Palm buttons.

Note: I initially was using the larger font as the default for KDIC when running it as a stand-alone program. Well, KDIC DA inherits KDIC preferences so it too was using the large font. What I discovered was that on my Palm V you couldn't see the results when using the large font with KDIC DA. So, if you have a small screen size make sure to set the KDIC preference to small font if you plan to use KDIC DA.

Dictionary Programs
As I said, KDIC is a platform; it DOES NOT include dictionary files, but many freely available dictionaries are built on this platform. I will list some of these below.

• Hoshi Takanori's Dictionaries for KDIC
  Basically, you will find seven dictionaries on this site: three are English-Japanese, two are Japanese-English, and two are experimental dictionaries (both E-J). The two experimental files will display the results in either kana only or kanji with kana in parenthesis. I believe all files are based on the amazing work of Jim Breen, EDICT.
  
  For my use, I think the KdicDB (EDICT J-E kanji - 9,223 words, 390 kB) and the KdicDB (EDICT E-J kanji - 9,592 words, 396 kB) files are the two I will try out.
  
  
• Todd Rudick's KDIC dictionaries for people learning Japanese
  Todd Rudick, creator of the useful Rikai site, has created his own KDIC dictionary files based on EDICT, appropriate for Japanese learners. He has made small & large versions of each file, so people can choose what suits them best. He claims that with these dictionaries and other software installed on his Palm, he can sit in a cafe and read a Japanese novel without lugging around a giant reference and/or taking 5 minute breaks to look something up by stroke counts.
  
  There are currently four files available (actually eight because each file is available in a "small" and a "large" format to fit different memory requirements � I have listed the "small" file size):
  
  
  1. English To Japanese (613 kB) � as far as I can tell, this is Todd's version of Hoshi Takanori's E-J files.
  2. Japanese by Sound (431 kB) � I think this is Todd's version of a J-E file but the input method is kana not romaji (unlike Hoshi takanori's files).
  3. Japanese by Written Form (606 kB) � this is Todd's J-E file for Kanji input, which means naturally that you must have software that allows handwriting recognition.
  4. Japanese Character Dictionary (98 kB) � The other missing piece of the puzzle for foreigners learning Japanese has always been a Kanji dictionary. Well, here's Todd's version. He hasn't included all the goodies to preserve space--just readings and "meanings".

Note: At first I installed Hoshi Takanori's dictionary files, but afterwards I switched to Todd Rudick's files (all but Japanese by Written Form) to see the difference. Without scientific testing, they seemed to contain more words (even the "small" files) and of course the character dictionary doesn't exist with Hoshi's files. At first I was worried about losing the kana display from Hoshi's files but then I realized that Todd's files have that as well.

Other Programs

• Dokusha
  From the User's Manual: Dokusha (Japanese for reader) is an integrated Japanese text reader, Japanese-English dictionary, Kanji dictionary and study system for Palm Connected Organizers. It is aimed at English speakers learning the Japanese language. It is an ideal self-study tool which lets you do much of your language learning directly on the Palm device. Best of all, it is FREE software
  
  I think this program is basically an alternative to KDIC, plus some nifty extra features. I have seen it mentioned several places and it may just be the nicest program out there, but it is probably only a serious option for those who have a fair amount of memory on their PDA (meaning my 2MB Palm V is out). The basic program without any of the useful dictionary files is 920K and, unlike some of the KDIC dictionary files, the Dokusha dictionary files don't seem to have a small version (so the J-E dictionary, for example, is almost 4MB!)
  
  So, what are some of those nice features I mentioned? Well, besides having what seems to be one of the most flexible and comprehensive kanji lookup systems (compound kanji, radical lookup, stroke count, code lookup, complete individual kanji details, JIS browser, etc.), you can also read Japanese texts that are in standard DOC format and do quick dictionary and kanji searches for words and kanji in the document. There is also a flashcard study program (with built-in sets for each grade) as well as a kanji explorer (show related kanji) that might be helpful as a study aid. Another neat feature is the ability to search for homonyms (words with the same pronunciation).
  
  One potential drawback to this software is that, unless I missed something, there doesn't appear to be an E-J file.
  
  
• Radic for PalmOS
  Radic is a small and free application for the PalmOS environment that allows the user to identify Japanese kanji by their radicals. Since there are a lot less radicals than kanji, identifying them this way makes life for the agonized student of the Japanese language a bit easier. Radic is best used together with KDIC. To display the Japanese characters Japanese language support must be installed on the Palm (e.g. J-OS).
  FEATURES:
  �- lookup kanji by their radicals
  �- display the English meaning of radicals
  �- edit the results to compose a complete Japanese word
  �- feed the found word to KDIC or KDIC_DA
  �- use different fonts for the radical table and the results
  
  
• Yomeru 5
  For people that want to display Japanese on their PDA, but cant afford CJKOS/J-OS or just don't want to pay for anything, a good try is this freeware Japanese display program.
  
  
• Daifugou Dictionary for POBox
  This page is all in Japanese so I don't know what it says exactly and I haven't seen any reviews of it.
  
  
• KingKanji
  KingKanji is a Japanese / kanji flashcard program for Windows, Palm, and CE devices. It is a commercial product (~$25). According to at least one review I saw, it is worth the price.
  
  
• Kanjitable
  From the website: "KanjiTable is a small application for the PalmPilot, designed to display Japanese characters. A small dictionary, basically. It includes a test program, KanjiTest, designed to help people remember kanji. Because of popular demand, I have released the source. You'll need linux with libc6 and all the pilot tools to compile it; it will probably never compile under Windows. I ceased development on this over a year ago�While I have had reports of problems under later versions of the operating system, I do not plan to fix things. Perhaps if I ever get a later version of the Palmpilot. Things DO work under the archaic version I was using."
  
  
• Ivan Kanis' PocketKanji
  "It's not easy learning to read Japanese. First, you have to look up a single character out of thousands of possibilities. Once you've found the character it will have at least two different pronunciations; each pronunciation will lead to a different meaning. Using the selected phonetics of the character, you then look it up in an English/Japanese dictionary. Because of the multiple phonetic choices, it is very time consuming and tedious. With PocketKanji you simply draw the Japanese character and then look up the definition. It is much, much faster."
  Note: see PAdict below�
  
  
• PAdict
  This program is a take-off and enhancement of the development of PocketKanji since that program's creator no longer had time to maintain it.
  
  
• JStroke
  This is a program that basically allows you to write kanji characters and then have the JIS codes displayed. Why? Well, apparently it is quite easy to look up kanji by this code on many denshi-jisho (e.g. Wordtank). So, this would serve as a tool for those with both a denshi-jisho and a Palm.
  
  

Non-PalmOS Devices
PocketPC OS
I have read that the PocketPC OS recognizes Japanese language input standard so for those of you with that platform you won't have to get an IME (Input Method Editor), most of which (e.g. J-OS, CJKOS, etc.) are not free.

Update (02-11-05): I recently heard from Andrew Shuttleworth, who runs the site Pocket PC Japan which offers news, views, reviews and resources for Pocket PCs and Japan/Japanese. Do check it out.

Sharp Zaurus
I own a version of Sharp's Zaurus PDA that I bought in Tokyo specifically for its built-in dictionary capability. This is my main denshi-jisho. The reason I like it is that it has character writing capability standard whereas so few standard electronic dictionaries do. Well, apparently some Zaurus models don't have this dictionary so some folks have written PalmOS like programs to turn their Zaurus into a study tool.

• KanjiNirvana
  KanjiNirvana is a kanji reference and learning tool for Sharp's SL5x00 and A300 Zaurus PDA's. It is aimed at students of the Japanese language and anyone else who is interested in Japanese characters. �
  
  When reading a text you very often encounter a kanji you haven't memorized yet and a lot of time has to be spend finding the character in a kanji dictionary. After finding it you normally would like to memorize it, so that you don't have to look it up again and again. KanjiNirvana combines a flexible kanji lookup method with a simple kanji quiz for memorizing to help with these two common tasks.
  
  See a screenshot at: http://www.wbcd.org/zaurus/z11.jpg.
  
  
• Arne Schmidt's Advanced Flashcards
  Arne Schmidt has a page dedicated the Sharp SL series PDA. He has also created a kanji flashcard program that runs on Windows, Mac, Linux and others (by others I presume that means Zaurus).
  

Windows CE

• JDIC & JREADER by Jim Breen may be an answer for Windows CE PDAs. Read an old article of his here.
  
  
• LexiKAN
  LexiKAN is a powerful and versatile software tool for learning to read and write Japanese kanji, hiragana, and katakana. It is not free (about $35) and according to the site it requires Windows OS. However, somewhere I read about a guy with a Palm PDA who claimed to be using it so who knows. Also, that same guy claimed it could export flashcard lists to KingKanji, making it really convenient to be able to study the same kanji and compound words on his home PC and on his Palm Pilot.
  
  
• JavaDict
  "JavaDict is a desktop Japanese/English vocabulary and character reference dictionary tool. If you can correctly write the character (a skill quickly learned) you'll have the meaning and reading in seconds. If you're a beginner or can't figure out the stroke-order, you can fall back on Jack Halpern's famous 'Skip' Method, which allows you to describe the shape of the character and pick it out of a small list. But unlike Halpern's dictionary, you won't have to search through 500-some-odd pages to find the right shape, nor will you have to memorize the numbers or even the exceptions to the system--with JavaDict everything is graphical and self-explanatory.
  
  What? You've already memorized the 200-or-so radicals required to use the Japanese 'Bushu' method? Well, that's included too; and again, you'll find your character much faster than you would flipping through a book."
  
  Since this program runs on Java, it will work in theory on any platform that has a Java virtual machine installed.
  
  

Miscellaneous Info

• I know someone who bought a Sony Clie during his last trip to Japan and said it came with a Japanese dictionary that is pretty good. I don't know how good or if this is a standard feature (maybe it is, but keep in mind he bought his in Japan with a Japanese OS).
  
  
• Jonathon Delacour, who has an interesting blog, has written about his decision to purchase a Sony Clie and use it solely to study kanji and Japanese. Read about it here.
  
  
• Jim Breen has put together a Handhelds mini-FAQ
  

Conclusions
So, what have I taken away from all my research? Basically, if you are considering the purchase of a Wordtank or similar denshi jisho, think twice. These days, you can use a PDA to get the same and even more capabilities. And, considering the prices of some of the dictionaries compared to picking up a used (or even new) PDA, it might be the same or cheaper. Of course, if you already have a PDA with a decent amount of memory, your price point has just dropped. So, don't be scared by the technology involved. Just give it a try!