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RTOS for 8051


I have to make an rtos for 8051. this is initial state and i will really appreciate if someone can answer these questions :

1: what are the functions performed by bootloader during startup of the chip? if i can exceute a program on my chip stored at any location in memory then wht do i mean by making a separate OS?

2:will i require memmory mapping programs too such as page management or is it all already taken care by bootloader?

ur ideas will be of gr8 help




  • johnsonmejohnsonme Member Posts: 57
    Hi Sony,

    I really appreciate your efforts in designing an RTOS for 8051. But so many are available free of cost on the net. If you have Keil, RTX51 ships with that.

    A boot loader initializes the chip. This can range from checking the RAM to initializing the stack pointer. All the I/O pins are initialized by this program.
    RTOS comes into picture when so many tasks are to be executed parallely in real time. But as you know, a cpu can execute only one task at a time. So the technique is to switch the tasks very frequently so as to make the apperance of simultenous multitasking. Without a real time kernel this is impossible.
    As far as an embedded system is considered, display and memory is the biggest constrain. Paging is appicable only to huge memory models like a PC. With just 128 bytes of RAM, you can not store even the page tables........ ;)

    Try reading "Operating system concepts" by gange or just mail me at for some presentations about the memory management in operating systems.

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