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-- Is Palm OS multitasking? (http://discussion.visorcentral.com/vcforum/showthread.php?threadid=462)

Can the palm OS perform functions in the background ? I was wondering if you could play an mp3 while typing in the todo file or while reading email ?

Thanks

Chris

The answer to your question is sorta. The answer to your delima (sp?) is yes. The Innogear MP3 Player states that you will be able to play MP3s while performing other tasks.

The OS can perform multiple functions, but requires specialy written software for it. The one that comes to mind is a "pop-up" calculator that runs "in front" of a running application and then returns you. I doubt this it true multitasking, but it works. I have also seen a hack that adds a tool bar to the Palm that runs all the time.

Check out http://www.innogear.com for more info on their MP3 player.

BZZZT! No. Palm OS -cannot- mulitask. Thats why Palm is going to EPOC32 for the next generation kernel.

Its a limitation of the license Palm OS has with the company they licensed their kernel from, KADAK.

Read my article on this in PalmPower:
http://www.palmpower.com/issues/iss...ninotwo001.html


------------------
Jason Perlow

Contributing Editor, PalmPower Magazine
www.palmpower.com

Sr. Technical Editor, Windows CE Power
www.windowscepower.com

Read My Articles at my home page:

www.argonautsystems.com

Jason,

...The PalmOS, as implemented on the Pilot and Visor, does have a multitasking kernel.

From the "Palm OS Programmer's Companion", published by Palm:

"Palm OS has a preemptive multitasking kernel that provides basic task management.

Most applications don't need the microkernel services because they are handled automatically by the system. This functionality is provided mainly for internal use by the system software or for certain special purpose applications.

In this version of the Palm OS (3.3), there is only one user interface application running at a time. [...] Only system software can launch a separate task. The multi-tasking API is not available to developer applications".

As to what this means for springboards, I'm not sure. But I'm pretty sure that you can play MP3's at the same time you do something else on your Visor, because the MP3 playback is handled almost entirely on the springboard, and doesn't require a task on the Visor CPU.

[This message has been edited by JHromadka (edited 10-28-1999).]

At the lowest level, the line between multitasking and interrupt-driven execution is pretty blurry. A lot of simple multitasking implementations are just CPU timeslice shares, which is identical to having an interrupt-driven watchdog that pops up and pushes different application code onto the stack.

When you really think about it, every multitasking OS comes down to this, although modern ones have many levels of abstraction to allow multiple programs access to resources (i.e. virtual IRQs)

Even if all the Palm does is allow DOS-style TSRs that modify the graffiti-input or hard button vector tables, you still get the appearance of multitasking. (it seems that an app is "running"...waiting for input to be filtered) If (I don't know if this is possible, but I'm guessing it is) you bind your code to a clock tick vector of some kind, then you can fiddle with things and then restore the CPU state so that the foreground app doesn't even notice.

This lets you do things that you would commonly refer to as multitasking, but remember that DOS had these same capabilities. There are actually DOS programs out there that will allow you to task switch and even do real simultaneous-execution multitasking.

So the moral of the story is that the limitations in most software can be overcome...DOS certainly was never built to multitask, with all the non-reentrant code it contains. The caveat is that an OS built from the ground up to multitask is probably both easier on programmers and more powerful in its feature set.

mportuesi:

"I'm glad I haven't read any of your pages... The PalmOS, as implemented on the Pilot and Visor, does have a multitasking kernel."

If you had READ my article, which obviously you didn't, you would see that I explain that while the KADAK real-time kernel can multitask, 3Com's license prohibits developers from using those capabilities.

Their disclaimer is clear cut. Get your facts straight, and don't be so quick to dismiss people or accuse them of ignorance.


------------------
Jason Perlow

Contributing Editor, PalmPower Magazine www.palmpower.com

Sr. Technical Editor, Windows CE Power www.windowscepower.com

Read My Articles at my home page:
www.argonautsystems.com

[This message has been edited by JHromadka (edited 10-28-1999).]

Jason,

Your article in this thread, right above mine, says "No. Palm OS cannot multitask." That doesn't leave a lot of room for re-interpretation where I come from.

As for your article, let's just say that I wasn't compelled to read it based on the accuracy of your post to this forum.

If you're going to call yourself a technical journalist, then be prepared to be held to a higher standard of accuracy, and clear prose, than the other people who post in public forums.


[This message has been edited by mportuesi (edited 10-27-1999).]

Perlow:

Thank-you for an interesting read in the form of your article ... and nice summary

So to get a clear answer out of you ... will the Visor (with its current OS) be able to play an mp3 while I type in my contact list (at the same time)?

Thanks

Chris

Now..Now boys! Don't make me come in there and seperate you two!

Sounds like someone needs a slice of Prozac pie.,