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From: warwicks@telusplanet.net (Chris Warwick)
Subject: Re: Space Station S/W in Ada -- No Tasking?
Date: 1998/05/08
Message-ID: <6j1vsg$eh9@priv-sys04-le0.agt.net>#1/1
X-Deja-AN: 351745058
References: <354dadfd.2883074@news.mindspring.com>
 <EACHUS.98May6171227@spectre.mitre.org>
Organization: gerf inc.
Newsgroups: comp.lang.ada
Date: 1998-05-08T00:00:00+00:00
List-Id: <comp.lang.ada>


The design for the chunk of flight software that I saw certainly had Ada 
tasks... So, I presume there is no restriction to prevent the use of Ada 
tasks... The problem we had was the Alsys Ada83 compiler was taking too long 
for a task context switch and thus we were unable to determine the respose 
time for an interrupt.

The other stuggle we had was with the fact that, despite the fact that we were 
trying to use static memory definitions, the compiler still insisted on 
pre-loading memory as part of its startup operation. Thus the code was taking 
so long to start that the watch-dog timer would keep re-starting the 
processor, i.e., our keep alive interrupt handler was never getting started.

This is item number 2 in my list of why I hate some Ada83 compilers. Item 
number 1 was with the Alsys DOS compiler that thought it was reasonable for 
DOS interrupts to halt all Ada processing in all tasks. It has been pointed 
out to me that this is 100% compliant to the LRM, and to use Mr. Dewar's 
words, makes the compiler 100% useless...