Psion Epoc OPL Program

The only miniature computer with a programming language built in.

Psion Organiser object oriented programming language, the built in software.


Turning a Program into an Application

After you write a program, and get it all working, make it easier to use by turning it into an application. An application has a number, appears in your list of applications in Extra Bars, and has an icon.

Unique Identifying Number (UID)

Psion Epoc applications and icons have a unique identifying number (UID), and this is also how Psion applications identify their own files. If you plan to write an application, get a supply of UID numbers from Symbian by emailing a request to uid at

For personal applications, you can simply use any UID above &05000000, which at least will not conflict with built in applications nor any shareware with an officially assigned UID. However if you think you might release your application to others, get an official UID and use it.

In the header of your program, you add the UID, and the icon name.

APP MyNewApp,&05000013
ICON "MyNewApp.mbm"

Creating the Icon

Your icon is a standard Psion mbm (multibitmap) file consisting of six images. There are 48x48, 32x32 and 24x24 pixel versions of your icon (for different zoom levels) and also 3 masks, one for each image. The mask is black where the image is visible, and white where the icon is to be transparent. You could just do a 48x48 icon, and hope the zoom treats it well, but you get better results if you do the three sizes.

You could create these with the Psion Sketch application, however it may be easier to use a program like PaintShop Pro on a Windows PC to create the six bitmap files as BMPs. Not having an artistic touch, I think it is easier to start your icon design with a free sample icon from the PC world. There are collections of thousands of them out there. You can convert the BMPs to a single mbm with bmconv.exe, a DOS program that comes on your PsiWin CD.

Installing your Application

Translate your OPL application again to include the APP code. On your Psion, make a directory called MyNewApp in the System/Applications directory. Put your translated OPL and your mbm file there. Your application icon will now automatically appear in your Psion Extras Bar.

If supplying programs to other users, consider using Makesis to convert the application to a sis (software installation system) file.

Keyboard Shortcuts

Ctrl G Goto procedure named

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