Volume 2, Number 3 Copyright 1997 TGG July 14, 1997
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EDITOR: Jack Ganssle, firstname.lastname@example.org
- Mars Pathfinder
- Embedded Seminar in Boston
- Thought for the Week
- About The Embedded Muse
Mars Pathfinder withstood its spectacular descent and landing on Mars intact; the rover Sojourner is now happily scurrying about the planetís surface acquiring data.
The rover is quite a fascinating device. With an 11 minute time delay between the Earth and Mars it has to be rather autonomous, yet clearly thereís not much of an energy or size budget for a lot of computer horsepower. Sojourner is quite a little fellow after all, with a rather small solar array. Apparently itís capable of producing about 16 watts at peak solar illumination - not a lot of energy.
At http://mpfwww.jpl.nasa.gov/rover/descrip.html thereís a short but surprising description of Sojournerís power and computer subsystems. A single 80C85 processor controls the rover, handling communications, navigation, power management and science. 176K of PROM contains the firmware, with 576K of RAM used for data. Since the 80C85 has a only 64k address space, hardware maps sections of this memory in and out in 16k chunks.
It would be fascinating to understand the decision process that led the engineers to select a 20 year old CPU for this very modern mission. Certainly radiation hardening must have been important, as well as low power consumption and high reliability.
My hatís off to all of the engineers who built this amazing mix of the modern and the old, that has performed so well for the last week. Itís exciting to extend our presence - even if only virtually - to another planet.
Embedded Seminar! Boston - Thursday, September 18
One of the gratifying things about writing for the magazines and producing this newsletter is the response from so many of you. Since leaving the tool business Iíve been overwhelmed with requests for both private and public seminars - usually, the request goes, ďanything about embedded systemsĒ. So, Iíve decided to conduct a one-day class on embedded systems in Boston on September 18.
Itís called ďThe 24 Best Ideas for Developing Better Firmware FasterĒ, and is for the developer who is honestly looking for new ideas, but who wants to cut through the academic fluff of formal methodologies and immediately find better ways to work.
The focus is uniquely on embedded systems, where firmware can only be understood in the context of the hardware. Iíll talk about ways to link the hardware and software, to identify and stamp out bugs, to manage risk, and to meet impossible deadlines.
Colleges prepare people with a fine theoretical background, but the skills needed to schedule, manage, and complete a product come from casual mentoring by co-workers. Isnít it astonishing that such a technical, complex art is acquired by on-the-job experience? Why donít we train developers in the art of doing projects?
For more information check out www.ganssle.com or email email@example.com.
Thought for the Week
The World's Last C Bug:
status = GetRadarInfo();
if (status = 1)