RTEMS and 16 bit CPU

Joel Sherrill joel.sherrill at OARcorp.com
Wed Jan 3 14:31:21 UTC 2001

leonp at plris.com wrote:
> I am thinking of possibility to use RTEMS kernel with 16-bit CPU - C166 and
> will be thankful for any considerations from the RTEMS community about the
> complexity of this adventure.

The H8 is a 16-bit CPU.  The key issue is that a lot of operations
are currently done as u32's.  In particular, one thing on my wish
list has been to redo some of the fundamental types so they can be
selected as u32's or u16's (with limitations).  In particular,
the current object id is 32 bits so a lot of operations are performed
on that.  

I would consider this an optimization not a necessity since obviously
the H8 port did not require it.  But it would time and space

Similarly, some of the general issues about being able to tailor
core executive items such as the number of maximum priorities 
become more important as the resources are decreased. 

The only warts about the H8 port I recall were that there is an
8 bit variant of the h8 family and when you multilib you have to
build for that.  

> Thanks.
> Leon Pollak
> leonp at plris.com

Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
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