The Sony COM-2 HandHeld Computer

Finally, a small handheld computer with a keyboard that isn't a cell phone! I was almost to the point of building a small 8052-based computer just so I could have BASIC on the go, but the COM-2 is smaller and faster than anything I can make, plus it plays music and video and surfs the web via WiFi. Mainly though, it is possible to program the thing in HTML and javascript, even using its built-in text editor.

The COM-2 uses the NetFront 3.4 browser and has decent javascript and flash support, but like all mobile browsers something's gotta give to make it fit. In this case it only has a single resizeable proportional font, supports only a subset of javascript "ECMA-262" commands, no fancy stuff (iframes innerHTML scrollTop etc), focusing has limitations, and certain key events are not passed to the usual onkeydown/onkeypress event handlers, in particular space and backspace. Unless a workaround for the focus behavior can be found, either you've got to click on the input field the first time the app is loaded, or key handling methods have to be used with other keys substituted for space and backspace. Right and left arrows make sense. Granted I'm probably expecting too much but HTML/javascript is the only native COM-2 user programming language available and this thing is way cool and needs to be programmed. So whatever it takes to make it go. Besides it not being a cell phone, I chose the COM-2 because Sony encourages user programming and provides documentation on the mylo(tm)Labs site. A lot can be done using plain javascript but built-in libraries make it possible to write applications that read and write data files and access COM-2-specific features.

Simplicity cuts both ways... whereas most browsers are smart and display files that don't have .htm[l] extensions as plain text or using another application, the COM-2 NetFront 3.4 doesn't care, an html file can be named txt and still display html and run javascript just fine. This makes it possible to use the text editor to compose code, since only .txt files can be edited and the file manager does not permit changing the extension. This is something I hope doesn't get "fixed", if the browser couldn't "run" .txt files that would make it impossible to program it without using a PC unless other editor/file manager changes were also made, it's nice to be able to make a code change then in seconds test it. The last update added a GAME folder on the main screen, so any text files placed there can be quickly edited without invoking the file manager. Then I go back to the main screen, Web, Bookmarks, select the text file containing the thing I'm working on and there it is. To make a bookmark specify file:///c/GAME/filename.txt in the location box. Quickly accessing folders besides GAME would be nice but figuring out this javascript stuff is a game - there's a rush when it works! Of course all I've got to do is plug the thing into my PC and the file system opens and I can do whatever, but being able to program stuff without using any other facilities but the gadget puts it into a higher level of system functionality - self contained computer. Nice, and unexpected for a stock consumer-oriented device.

The COM-2 works fine with Ubuntu 8.04 or any other OS which recognizes standard fat-based media file systems. Don't be swayed by Windows-specific instructions, the COM-2 itself runs a version of Qt Linux and works fine with Linux systems. The COM-2 doesn't have a PDF reader but Ubuntu has a pdftohtml command (use the -c option) which does a fair to good job of converting documents into .html/image files which can be copied to and read on the COM-2.

BASIC for the COM-2

Javascript isn't my thing so first order of business was to find a BASIC for it. There are at least five BASIC interpreters written in javascript on the net, of these only ippleSoft BASIC worked on the COM-2, at least once I replaced the frames and document input and output with simple text boxes. I probably could have hacked some of the others to work, but ippleSoft is GPL and is designed to be modified and shared whereas the others don't permit or are fuzzy about such activities. Besides it is relatively simple and except for the interface pretty much self-contained making it mostly trivial to replace the I/O stuff with code that'll work on the COM-2 without having to touch the main javascript code. I don't really understand how the program works but it was not necessary to know much except for simple things like what functions to call for input and output (for echoing), what to do to stop the program (copy what the STOP command does), and how to parse things like variable names (find something with similar parameter syntax and adapt it). Except for brief encounters spanning many years I knew almost nothing about javascript before getting the COM-2, but after reading the javascript 1.3 docs (available here) a few times it starts to make sense. Good thing because I had to write a fair amount of code to implement a single unified "console" and work around issues like space and backspace not being registered as key events and the lack of text area scroll control, which I ended up "solving" by modifying the output function to limit the number of lines in the output text area, eliminating scroll bars altogether. Text scrolled off the top is lost, just like in the old days.

The original code had no INPUT statement, no wonder since event-driven "web and windows" programming doesn't provide a way to simply wait for a keystroke then keep going. Instead of fighting it (and to avoid having to do major mods) I implemented INPUT and GET so they simply set a javascript variable with the name of the variable to INPUT or GET user input into, then halt the program. When the user enters (or in the case of GET types) something the glue code sees that it's an input request, and in immediate mode (without echoing to the screen) issues "var=[number or string] : CONT" and the program resumes at the next line. It ain't right but works quite well provided there are no commands following the input request on the same line. Also the form INPUT "prompt", var is not supported, only simple INPUT|GET var[%|$]. Normally GET is only used with a string but I didn't bother to add code to prevent GET A (in which case pressing a non-numeric key returns 0).

Now that I can enter stuff I added buttons to operate numerical programs and do immediate calculations without having to use the keyboard. This part was easy, just had to arrange my handlers so button events could call them too. They might have to be made larger, but for now they're functional and permit 14 lines in the text area when the default text size is set to 18.

Finally I can now program the COM-2 for common electronics calculations...

A closer view...

Click Here to Run or right click link to download (6/13/08). Here's the help file.

This is a work in progress, subject to change. Note that per GPL terms the authors are not responsible for any errors or other consequences resulting from the use of this software. To view the source use your browser's view source function, or view or download isbas.txt.

The included BASIC "shop" program can be easily removed and replaced with other BASIC code, follow the form of the existing code and remember to write ' as \' to avoid ending the string early. Short programs can be entered in immediate mode and saved to browser cookies, click stop, enter new, enter the code, run, etc, then save filename (must not start with the name of a command). Load filename to reload, run filename to load and run, cat to list files. See the help file. On a PC this seems to be reliable but once on the COM-2 after surfing the web I found my programs gone so I don't trust it. The safest and most convienient storage method is to directly encode the program into copies of the interpreter script, this results in about 50K overhead per thing but compared to the size of other things that's not much.

Implementation and other notes...

This version is adapted to the COM-2, and does not support pasting code. For use on a PC the original input box method or some other method that uses the text area might be better since that would permit pasting in BASIC programs. I didn't do it that way since 1) not possible on the COM-2 so not an issue, 2) the COM-2 seems to be unable to focus text input fields in a way that can be immediately typed into without clicking on first, was able to make it sort of work using the original Enter button but not if the enter key was pressed, and 3) when using a single text area for both input and output it always returned the cursor to the top. So I opted for a single read-only text area using key handlers to deposit typed keystrokes into it.

There is no cursor, but text is always added to the end of the text area so it's fairly predictable where the invisible cursor is (just no feedback for space and backspace - which have to be entered either using the on-screen buttons or using arrow key substitutes). I'd like to add a cursor but doing that is a bit more difficult than it sounds as the cursor character would have to be removed from all input operations and added to all output operations (including error messages), and only if in immediate or input mode. If not done very carefully something will get it wrong under some condition, every code path and state would have to be considered. I can use it just fine without a cursor so at the moment doesn't seem worth the effort unless I get in the mood for some extreme programming.

Presently there is no DIM for arrays. I don't really need it for programming calculations, and presently I don't know enough about how the core interpreter code works to implement it. For the kind of stuff I run having DIM would only permit some games to work but as the COM-2 has no fixed-pitch font it really wouldn't do any good. To support BASIC board games on the COM-2 the console area would have to be implemented as a table array rather than a simple text area and it starts to get really complicated fast. I'm thrilled just to be able to program calculations.

Printing table data... make sure numeric data is rounded off to less than 8 characters using an expression like for example INT(N*1000+0.5)/1000 to round to 3 decimal places. PRINT I,J etc will approximately line up data into columns, PRINT I;"[tab]";J works better ([tab] means press the tab key).

6/20/08 - Updated isbas.htm/.txt to 6/13/08 code with added functions for calculating capacitor charge time. No change to the interpreter itself. While writing the code (using FireFox 2) I had problems including IF statements following GOSUB statements on the same line so used separate lines, oddly I can no longer duplicate the problem with a test case. Possibly a javascript error that got fixed with some update but still avoiding IF after GOSUB in case that triggers a glitch in some browsers. I can't help but notice javascript isn't exactly a precise language, more like a moving target subject to change behavior with each new version or update. FireFox 3 actually displays a cursor.. was considering hard-programming that but now I won't as then FF3 would show double cursors. I use ISBAS frequently (both running the shop program and punching in equations in immediate mode) and lack of a cursor on the COM-2 has not been a problem.

Last modified 6/20/08, Terry Newton (
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