Ask about RXT-51 Tiny (Keil C real-time os)

[binhqt]

Hello.

I have just studied about RTX51 Tiny. And i know that if i enable 'Round-Robin Task Switching' then Tasks execute for the duration of their time-slice. Then, RTX51 Tiny switches to the next task that is ready to run. And if i disable 'Round-Robin Task Switching' by set the variable TIMESHARING to 0 in the Conf_tny.A51file. I must call the os_wait function or the os_switch_task function somewhere in each task. These functions signal RTX51 Tiny to switch to another task (if i don't call os_wait or os_switch_task in each task, it don't switch to another task. I mean my my multitasking aplication not working).

But i read an example project in RtxTiny2 folder which have name Ex1. This example have three tasks job0, job1 and job2 these job are simply increment counters. In each tasks in this project it don't use any os_wait or os_switch_task function. So i wonder if it switch to another task (i wonder if After job0 executes, RTX51 Tiny switches to job1. After job1 executes, RTX51 Tiny switches to job2, After job2 executes RTX51 Tiny switches back to job0...)
I see that the variable TIMESHARING is set to 0, it mean disable 'Round-Robin Task Switching'.
Could you explain this problem?

the Ex1.zip is the code of this example