BeatPad Timing Issues

Accuracy
The accuracy of this version of BeatPad is based upon the Palm OS supported 10 millisecond clock. Palm devices (made by Palm Computing and various licensees of the operating system) use a number of different processors so timing not supported by the Palm OS is problematic. This means that, because BeatPad keeps a more acurate clock internally, then finds the nearest System clock during playback, notes played by BeatPad have an accuracy of +/- 5 milliseconds. We hope to improve this accuracy in future versions. Since BeatPad uses a more accurate clock internally, tempos are more accurate over longer time scales (i.e. tempos of 122bpm and 123bpm might have the same gap between two particular notes, but over the course of a minute, they will send a different number of beats).

Possible glitches in timing
The Palm OS is a multi-threaded operating system. Although only one application can run at a time, the operating system itself is working on several tasks simultaneously. This means that even though BeatPad completely takes over the system while it is playing (you will get no battery warnings or other interruptions during playback... you can't even turn the power off until you tap on the stop button) the system is still running these other tasks in the background. Such tasks include monitoring the touch sensitive screen, and and the real-time clock.

Regarding the touch sensitive screen, if you hold the pen down in one place for long enough, you can cause gaps and held notes in BeatPad. This seems to be because the background task that is monitoring the screen gets into a loop while monitoring the "Pen Down state". This is a feature/bug of the Palm OS and can interrupt the operation of any Palm software. Regarding the Palm's real-time clock there can be a pause in BeatPad's playback at midnight, for example. This is because the operating system must update the date at midnight, and inform the built-in applications (like the datebook) that we have begun a new day. Be aware of this if using BeatPad for late night performance; it can be easily avoided by simply setting the Palm's clock to be earlier in the day.

Other Software
Other software can also make use of these background system operations and may have an effect on BeatPads accuracy. For example the Keyboard Utility that comes with Palm's new folding keyboard has an "enable keyboard" checkbox; when this is checked the utility constantly polls for events which will cause a repeating glitch in BeatPad playback (we've found it to cause a short hiccup approximately every second in testing). This can easily be remedied by unchecking this box whenever the keyboard isn't being used.

We cannot test every application, but other software that is very time dependant or using background system features (like optional handwriting recognition software using the touch sensitive screen or other software using the timer or serial port) may have to be disabled for accurate playback from BeatPad. Be especially aware of any Hackmaster hacks you are using if you experience any problems. Even though BeatPad uses only supported features of the Palm OS, we cannot be responsible for software from other companies, or problems inherent in the Palm OS.



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