Tom,

     So what is the solution to thier problem?

     A thread about buidling a basic OS on a PIC in this list would
     probably interest a few people here.

     regards
     SW.


______________________________ Reply Separator _________________________________
Subject: Re: "SOS:Info For Real Time OS on Microchip's 17c42a
        micro
Author:  trogers@timetech.com at INTERNET
Date:    30/07/97 08:48


Byron A Jeff wrote:

> We've just finished having this discussion a couple of weeks ago.
> Frankly
> it cannot be done easily. This is due to the fact that the system
> stack
> isn't mapped into a user accessible address space. So the typical
> mechanism,
> stack swapping, isn't available.

Guys, this is baloney. There isn't any specific requirement for an
addressable stack in any of the basic real time programming principles.
This psuedo-requirement is a result of spending too much time with one
predominant style of chip architecture. The requirements of a real time
system are not architecture specific.

Think about it: what does the stack have to do with a semaphore? If you
go back to, say, Djikstra's paper and follow your nose, you won't have
this confusion.

Tom Rogers  Vp-R&D  Time Tech Inc.