At that time I did not have a laptop, and I wanted to do most of the programming when on the road - hence the choice of the development platform. More than once I have been asked by our fellow LX-ers about how it can be done. Here it is.

Some writers used to recommend Turbo Pascal 3 for HP Palmtops. I wouldn't. TP3 was a great compiler back in '86, but the language was not as powerful as the later versions from 5.0 up. First of all, it was missing the modular features of the later releases; you could not use it to build self-contained, precompiled units. This is a large setback in all but the most elementary applications. The language standard has vastly improved since then, and so have the libraries.

The bottom line: I am recommending TP7, but if you happen to have a copy of Version 5.5 or 6, you may just stay with it. (These earlier versions have a slight advantage of taking up somewhat less disk space than Version 7.)

• The command line compiler, tpc.exe. It is amazing that an advanced compiler takes only 75,400 bytes of disk space, less than a stupid splash screen of many Windows applications.
• The Turbo Pascal runtime library, turbo.tpl - 81,888 bytes.

Just go to DOS and type "diet tpc.exe", making sure that DOS will find Diet in its path. Then forget about what you just did, TPX will run like usual on your palmtop, with only a slight delay upon startup.

Go to DOS, create a new temporary directory, copy there tpumover.exe and turbo.tpl, and then, while in that directory, type "tpumover turbo.tpl -graph -overlay". After the new turbo.tpl has been transferred to your palmtop, the temporary directory can be safely deleted. The process reduces the library size to just 44,544 bytes!

The bad thing about command line tools is that they use command line switches, quite hard to remember. The best way around this is to create a small batch file, invoking the compiler and setting the switches the way you usually need them. The batch I'm using, p.bat, is really a one-liner:

@ECHO OFF
A:\TP\TPC %1 /$S-/$A-/$I-/$V-/L/$N+/$E+/$X+/$F+/M

Refer to the Turbo Pascal documentation what the switches mean, but I found that this combination is just right form my palmtop needs. Of course, you may have to change the compiler path from a:\tp\ to wherever you've put it.

To compile a program with the main file named, say, myprog.pas, go to DOS, switch to the directory with your Pascal source code and type p myprog. After a few seconds the compilation will be complete and myprog.exe will be created on your RAMdisk.

How much available DOS memory you need for the compilation depends on the size of the program you are compiling. The largest program I've ever built on the 95 or 100LX was my (to put it mildly) calculator, Ex, with about eight thousand lines, or 100,000 bytes of code in a total of 40 units. Turbo Pascal was quite happy compiling it in 300k of DOS memory.

The compiler speed is more than respectable. The complete recompilation of all Ex units takes about 18 seconds on my 100LX and, if I remember right, about three times longer on a 95LX (which I no longer have).

On my 95LX with 500k of RAM left (after the RAMdisk, that is) I used to do all this while in DOS, from within the VDE editor. The editor allows you to define a macro taking the name of the current file as an argument so that, for example, pressing Esc-P would compile the edited file, and Esc-R - run the compiled program; all without leaving the editor.

You can do it the same way on a 100/200LX, but for that machine I have switched to another approach, working directly from the Filer, without leaving to DOS.

Thanks to Buddy I am able to do everything from the Filer. I've assigned the comma key, when pressed over a .pas file, to run p.bat with that file's name as a parameter, while in order to edit the .pas file with the buit-in Memo editor, it is enough to press Enter twice.

Pressing Enter over the .exe file will execute the compiled program. Most importantly, you do not have to exit Memo to perform the other steps (although you have to remember to save the source file before doing this).

In principle, with the in-line assembly code option of Turbo Pascal, you can access any low-level functionality of your HP. That is, however, quite complicated and not too well documented. This is why I am limiting myself to DOS programs running on the LX and not really interacting with the Program Manager.

There is one thing worth trying and not too difficult: LX graphics programming. Obviously, the TP runtime library does not address this issue, but the assembly code for basic graphic primitives (line, point, circle etc.) has been published by a number of authors. Based on that, I wrote myself a small Turbo Pascal graphics unit for the LX palmtops, usable on both 95 and 100/200LX. This is how Ex draws function graphs, histograms and scatter plots. If you are interested, try it!