In this example, I set up a very simple program called TRACKER that just uses a FOR NEXT loop
to iterate a variable from 1 to 10 and prints the variable value at each step:
FOR I = 1 TO 10
PRINT I
NEXT
Any errors that occur during the program execution will also be displayed on screen. Finally if and
when the program completes, “End.” will be shown. Remember that an actual flight program
should contain an infinite loop that never completes. Once a program completes, the U4B system
will sit and do nothing more until told to do so, or until the power is cycled. At 12km altitude there’s
nobody with a PC terminal emulator and USB connection to tell it what to do…
3.3 Text editor
The Text editor application is used to enter and edit your programs or other files on the disk.
It is also a full IDE (Integrated Development Environment). U4B programs are written in a simple
type of BASIC programming language, which is compiled to check for errors and compact the
program so it uses less disk space. The IDE allows compilation of the program, shows errors, and
contains a debugger that may be used to step through the program one line at a time.
Note that the editor always uses UPPERCASE characters – you don’t need to press Shift or
CapsLock on your keyboard, everything will automatically be converted to UPPERCASE for you.
The upper part of the screens shows the text file contents; the lower lines provide information
about the number of lines, percentage memory used, and state of the file (modified or not);
together with a helpful list of available keyboard operations.
•
Ctrl-O: Open a file from disk
•
Ctrl-S: Save a file to disk
U4B operating manual Rev 1.00
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