Re: Disobeying jet engines - why?

On Fri, 25 Jan 2008 15:38:15 +0000, Martin Brown
<|||newspam|||@nezumi.demon.co.uk> wrote:


I do embedded realtime apps that have no OS. I've written a few
RTOS's, but haven't needed to use one in a long time.

If the code is...

START: do thing1
do thing2
do thing3
goto START

where is the OS?

The OS is the bit that should step in when one of thing1, thing2 or
thing3 fails to complete. Most non-trivial embedded applications have
some kind of RT kernel underpinning the allocation of resources.

I doubt it. You can do arbitrarily non-trivial apps with just state
machines running in a loop. The only RTOS would then be a hardware
watchdog timer.

The code blocks can themselves use whatever resources they want,
assuming they are neither hostile nor stupid. The rare
allocation-of-resources situation can be handled by code blocks
locking out interrupts, or with simple flags.

If ever you assign a programmer to do a deep-embedded app, and he says
"first, we'll have to write/buy an rtos", fire him instantly.


John


.

Relevant Pages