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From: d-struble@ti.com (Dave Struble)
Subject: Need help with PowerPC/Ada and realtime tasking
Date: 1996/05/17
Message-ID: <d-struble.107.001A95C3@ti.com>#1/1
X-Deja-AN: 155340584
organization: Texas Instruments
newsgroups: comp.lang.ada
Date: 1996-05-17T00:00:00+00:00
List-Id: <comp.lang.ada>


I am an experienced real time system designer who is just learning
how to use Ada.  I am also just learning how to use the Power PC
(my target system).  I am seeking help to analyze some alternative 
ways to implement a hard real time application in Ada on the Power 
PC.  Actually, on a multiprocessor configuration.  
The intent is to design the software in such a way that dependence 
on the number of processors is minimized.

This is very "hard" real time -- life critical application and 
interrupts occurring at a frequency roughly 1/100 the speed of
the memory during peak situations (although most of the
time it is somewhat less frequently).

I seek two kinds of information:
I. - generic information on implementing hard real time applications
  in Ada - applications where the Ada tasking model cannot be used
  because:
  - the implementation of tasking is too slow
  - only a skeleton run time is in memory, and it does not support
     all Ada capabilities

II.- specific information pertaining to Ada on the Power PC.
Specifically, the Motorola 603e implementation.

The kinds of things I seek are:
- a textbook on real time applications in Ada
- a white paper or technical paper 
- an on-line document of some kind
- a series of hints or whatever from an expert

The kinds of information/questions I have are:

1) What sorts of approaches do people use for tasking when
   the Ada tasking model is too slow?  How machine independent
   can these be?
2) What approaches can be used for sharing memory between
  processes that may or may not be located in the same processor
  (but the processors do have some shared memory and some
  local memory)
3) What techniques are commonly used to synchronize?
4) What kinds of features do off-the-shelf run time systems
  offer to support these kinds of applications and what are
  the advantages and drawbacks of different systems/approaches?
5) What other questions should I be asking and what are their
  answers?
6) What pitfalls are likely?

My objective is threefold:
- to help design the software
- to select a run time system from among several candidates
- to help design the interrupt system (hardware and software)

Thanks for any help.
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-  Dave Struble                         |                           -
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