rracine@ajpo.sei.cmu.edu (04/24/89)
>Let me issue a challenge here. Can anyone tell me of a hard real-time >system which is operational now that was written in Ada? Or even a beta >version that is scheduled for delivery and operation before the year is >out? I'll bet no one can. We have been working with Ada for NASA systems for 6 years now. While it is true that we have nothing operational, that is only due to politics (no military service support for an oblique wing experimental aircraft). The software was designed, and coding was well underway. That was at least two years ago. The fastest loop was 10 milliseconds. Is that "hard" enough? We had a number of difficulties with meeting this deadline, but we only had problems with the fastest processing. We were able to use Ada tasking, for example, for slower rate processing. The 10 millisecond loop was a fairly simple interrupt driver. As with anything, we had to optimize the "hot" areas of the code. But we were well on the way when the project was canceled. We have a working prototype of a fault tolerant computer, which was designed for high reliability avionics systems . We have been working with NASA JSC and Langley on what is needed for their programs. As a subcontractor we have delivered code for a jet engine controller. Since it is not ours, we can not talk very much about it. Again, we were able to meet hard real-time constraints at least two years ago. And compilers are FINALLY, just now, getting good optimpizers. I would never say that Ada is perfect, but it is much better than anything in widespread use today. Especially with some of the packages we developed. We have other projects being worked on in Ada, and we are helping NASA JSC with Space Station Freedom real-time requirements. Those are a little farther in the future, but is built on the work we have done over the last 6 years. Please give me a call (net or phone) if you want more information. Roger Racine C. S. Draper Laboratory (617) 258-2489 rracine@ajpo.sei.cmu.edu