SysQuake LE

This chapter describes how to develop SQ files for SysQuake LE, the free, limited version of SysQuake. For more information about how SysQuake LE is licensed and how it can be acquired, please read the license file which accompanies it.

To preserve SysQuake's commercial viability (and indirectly SysQuake LE's), SysQuake LE has the following limitations:

No low-level input/output
Access to the file system is disabled. This has the benefit of preventing a malicious SQ file downloaded on the Internet from accessing and corrupting your files.
No extensions
Extensions are not loaded. Extensions are files which add new commands to LME, the language of SysQuake, e.g. for mathematical functions, for connection to hardware or for your own code developed in C. An example of such an extension file is LMELapack, which adds high-quality linear algebra functions based on the de-facto standard library LAPACK. Access to serial ports, though, has been integrated on some platforms.
Lower limit on the number of windows open simultaneously
On some platforms (such as Mac OS 9 and X), several SysQuake programs (SQ files) may be open simultaneously in different windows (on other platforms such as Windows, SysQuake itself can be launched more than once). SysQuake LE has a lower limit on the maximum number of windows.
No support for advanced data exchange
To make easier the exchange of data between SysQuake applications or with other software, SysQuake supports an advanced mechanism based on the Copy/Paste paradigm. Data conversion is performed when necessary in a transparent way.

SysQuake LE can be used as a viewer to illustrate complicated problems with dynamic graphics, or as a development environment for simple applications.

SysQuake LE as a viewer

As a viewer, SysQuake LE lets the user load interactive graphics and play with them to acquire a better, intuitive understanding of the meaning of the graphics. Files can be located locally on the hard disk or the cd-rom of the computer SysQuake LE runs on, or on the World Wide Web; in this case, the Web browser may be configured to launch SysQuake LE automatically when a link to an interactive graphic is clicked.

To use it effectively as a viewer, you must understand the role of SQ files (the "programs" of SysQuake) and SQD files (files which store the data and the state of an interactive session with SysQuake). As a viewer, it is better to prepare SQ files, because no assumption about the availability or location of SQ files is necessary.

There are mainly three ways to prepare SQ files before distributing them to illustrate theory with interactive graphics:

No programming
SysQuake is provided with SQ files which cover a large area of classical automatic control, signal processing, and other fields. You can open them (or an SQD file you have already saved), modify the settings until you are satisfied, and save the result as a new SQ file (in the File menu, select "Save As SQ File"; with some versions, select "Save As" and choose the SQ File format).
Editing existing SQ files
If you have an SQ file with most of the features you want, you can modify it to make it more suitable for SysQuake LE. For example, you can change the figure names (replacing "Result" with "Correlation between sin(t) and sign(sin(t))"), or the color of the curves. To make the SQ file smaller, you can replace the content of the data block with new settings in the init handler. You can also remove some of the menu handlers, the definitions of figures which are not displayed, and the functions which are never called.
Writing new SQ files from scratch
Writing an SQ file from scratch is of course also an option.

SysQuake LE as a development environment

Developing for SysQuake LE is very similar to developing for SysQuake. The lack of low-level file access and of the advanced data exchange mechanism makes more difficult to exchange data seamlessly with other applications.


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