it does kinda make sense that they could supply a software patch which would check to see if there was faulty memory and, if there was, make an alteration to the OS to stop it from accessing that area of memory.
Read the TRG FAQ. The patch has nothing to do with accessing "bad" areas of memory; in fact, the corruption doesn't even occur when the OS is running! The problem is the memory chip's faulty implementation of self-refresh mode used when the Palm is asleep. The patch changes the refresh mode used.
Speaking of reliability, what's been happening to Slashdot lately? I keep getting lots of Apache errors claiming the server is misconfigured. Reloading usually clears the error and loads the page. Sometimes Slashdot isn't responding at all. Last week response was so slow that I thought maybe another DoS attack was underway. What's the deal, Rob?
Well, I'm glad that we've started looking before a disaster, unlike 'Rendezvous With Rama'." Or Lucifer's Hammer.
The people of Earth were actually pretty lucky in those books. Humanity survived in both -- pretty well in Rama, not as well in Hammer. But they survived. It wouldn't take too big an asteroid to kill us all, so don't go kidding yourself that those books describe worst-case scenarios. They don't.
What is the origin of the Pan-Galactic Gargle Blaster, and how would you make one on Earth? I need to know.
Since you can't make one on Earth (the treaties could probably be ignored, but the laws of physics are going to be a bit tricky) you need to find a substitute. I've found the Zombie to be a crude but effective substitute. Some nice fruit juice, lots of Rum. YMMV.
Or you can always fall back to gin-and-tonics, which are available in every culture.
If you want to see something really cool, go unitedspacealliance.com or spaceflight.nasa.gov during a shuttle mission. You can see live orbiter telemetry -- not just some state vector-base orbital predictor, but actual telemetry. The applet even uses the same telemetry protocol as is used within mission control.
Actually, wouldn't it depend on whether Stephen had the GPL virus when Lucy was concieved? If his DNA was Proprietary at her conception, then her DNA should be Propriatry too, regardless of Stephen's current License state. What about Catherine's DNA? Does Lucy automatically inherit Cross-Licensing Rights from both parents? What if Catherine's DNA is under the BSD license? And does Lucy have to sign an NDA when she reaches legal age, or does she automatically receive her own License? Which license? Does she get to choose her own? Since her DNA is unique (though a Derivate Work of both parents') does she retain an Exclusive License? Is it Transferrable? Is it Revokable? Inquiring minds want to know.
The Dr. Bechly article was already done... over a week ago... maybe if you read articles, instead of bitching so much, you'd know this.
Maybe you should read the articles. Dr. Bechly's original article, which you linked to, was his original money offer. What this slashback contain, and what the first poster said should be a standalone article, was Dr. Bechly's withdrawal of the original offer. Read both and you'll see the difference.
To put this post back on-topic, I enjoyed reading Bechly's withdrawal of the offer, but I agree that it should have been an article of its own. Dr. Bechly's original offer was deemed significant enough that it was posted standalone. Surely today's text, including the interesting (and controversial?) issues raised, deserve the same consideration. Today's post was not only long enough to stand on its own, but the subject deserves its own discussion space, separate from the unrelated threads that will turn up here because of the other slashback topics.
Actually, I keep 2 sets of batteries and a charger handy for my Quicktake - it works pretty well for a low-end camera like that one. But for the mass market to take off, we need battery life comparable to a heavily used conventional camera, where you drop a new photo lithium battery in it every few months and then shoot away. Then you only need one spare in your pack, and if it dies you can replace it at any store.
I use three sets of batteries -- typically one set of NiMH cells in the camera, the other NiMH set in the charger, and a pack of Lithiums in the camera bag as my emergency backups. Lithium cells last a long time in a digicam. They're expensive, but they have a long shelf life (on the order of years) so they make great spares.
Your comments about conventional camera power management are right on the mark -- it's something we shouldn't have to worry about. But I'm willing to put up with it for the benefits of my digital camera.
This sort of thing has been discussed repeatedly and at length in the Risks Digest. You guys do read the Risks Digest, don't you?
The Risks Digest is more verbosely known as the Forum On Risks To The Public In Computers And Related Systems, ACM Committee on Computers and Public Policy, Peter G. Neumann, moderator. It's a great and fascinating thing to read; it covers almost any topic even tangentially related to the risks of using computers and digital systems, including privacy issues, Y2K issues, software in critical systems, encryption policy, etc., etc. It is known on usenet as comp.risks, and is also available via e-mail. It's an old forum; in the online archives you can read discussions following such famous events as the loss of the Shuttle Challenger and the Robert Morris Internet Worm. Highly recommended reading for anyone making software.
Unfortunately, those cameras cost about $1000, and you still get crappy battery life.
Get a set of 1600 mAH NiMH rechargeable batteries, minimize your use of the LCD screen (if possible), and you'll get reasonable battery life. With my Kodak DC290, I can take enough high-resolution photos to fill my 64MB CF card (about 100 photos at 1792x1200) using a freshly charged set of NiMH AA cells. I've also run some extremely long time-lapse photos on a single set of batteries: one low-res photo per minute for 5 hours.
I'm not saying that digicams don't suck power -- just that it's a manageable problem.
Not really an easter egg, because it was advertised on the box, but getting into it was just like any "real" easter egg... The Sega Genesis version of Pitfall Mayan Adventure contained an entire, fully playable, copy of the original Activision Pitfall game for the Atari 2600. To get into it, you had to play to a certain point in the game then do something particular. I forget the exact incantation, but it was really cool to see an old game entirely embedded inside a modern game.
Arguments about alcoholism can be backed up with statistics, medical evidence, and other objective data. But ethics are slippery concepts must be considered in light of the reputation of the presenter. If John Wayne Gacy tells me that murder is wrong, I'm going to laugh at him even though he's right. However, if he tells me to destroy criminal evidence, not just hide it, I can consider him an authority on the matter. Maybe in the academic world of Rhetoric you are right, but in this argument, Bertrand Meyer does not have a reputation (with me) that makes his arguments persuasive.
Besides, I read his article. He doesn't get it.
Meyer's assertions about C versus OO programmers were not about using object-oriented languages; they were about discipline. If Meyer had said "avoid undisciplined programmers" I would have no beef with him, but he said "avoid C hackers" then offered up a bunch of unsubstantiated reasons why C hackers == undisciplined programmers. It was, as Robert Martin said, bigotry, and it was not ethical.
First, attacking the author is not a valid way to attack an argument. The arguments in the article should be considered independently of the author.
Bullshit. The qualifications of the author to write about subject X are just as important as what the author says about subject X. If I think Bertand Meyer has expressed unethical positions in the past then I can hardly respect his present position on Ethics. What would you think of an essay entitled On Defending Faith and Fidelity in the Institution of Marriage when you learned that its author was named William Jefferson Clinton?
Second, criticising a programming language, and by extension those who use those programming languages, is hardly a profoundly unethical thing to do.
Meyer wasn't criticizing a programming language; he was criticizing the people who had used that language. There's a huge difference.
I'm not sure Bertrand Meyer is someone we should be listening to on matters of ethics. In his book Object Success Meyer expressed what I find to be an extremely unethical position when he expressed the opinion that C (and presumably C++) programmers, having learned too many bad habits, shouldn't be considered for "real" OO development projects. Hiring managers should look on them with suspicion, he suggested. In spite of his weasel words about "human betterment", I find this to be little more than an expression of prejudice about C/C++ programmers, and I find it unethical in the extreme.
Robert Martin, of Object Mentor, wrote a nice rebuttal to Bertrand Meyer, which he posted to comp.object and comp.lang.c++, among other Usenet groups.
The project that I thought you might be interested in is the development of a space shuttle flight computer emulator for linux described here.
I've seen that project description before, because I wrote it. I'm very familiar with the GPCE project because I'm the principal author of the C++ version. Unfortunately, none of our Dual partners in academia wanted to tackle the conversion of GPCE to little-endian architectures, so for now we can't run on Lintel systems.
Actually, AFAIK, the main reason is that old 386s are tested, tested and, once more, tested for space use.
You're thinking of the PGSCs, the IBM Thinkpad laptops that are carried onboard to help the crew do various non-critical tasks, usually (always?) related to payload operations. These are indeed old 386-based machines, radiation-hardened but still susceptible to crashes related to bit errors in RAM. They run Windows 95, so obviously they aren't used for critical ops. (BTW, linux has been run onboard too.)
The GPCs (General Purpose Computers) that run the flight software are IBM AP101-S computers, cousins to the IBM 360/370 architecture machines of the 1970's. The AP101 is a big-endian, 16-bit, 4 MIPS (appr.) machine that can address up to a megabyte (actually 2^19 16-bit halfwords) of memory. It has been extensively tested for space use, as you note, which is another reason NASA sticks with it. An earlier version of this computer, the AP101-B, flew earlier shuttle missions and has been used in military operations like the B-52.
I don't work with the FSW people, so I'm not sure about the details of their work flow, but I think it's safe to say that new code goes through several readings, probably both at the pseudo-code and code levels.
Schedule is driven by the planned date for launch, and worked backward from there. For example, if you're going to launch a mission at date L, then the crew begins training at L minus X months, which means that the software has to be ready for the SMS at L minus Y months, which means you have to begin design at L minus Z months, etc. I'm not sure what X, Y, Z and related time deltas are, but I believe they probably start planning at least a couple of years in advance.
I happen to work just down the hall from the guys who maintain and upgrade the shuttle Flight Software (FSW), and I can tell you they have a rigorous design, inspection, and test sequence that they go through before they fly new or modified code. The story around here (which I have no reason to doubt) is that the FSW team was one of the first SEI level-5 certified shops in the nation.
I can also tell you that NASA avoids having to make unnecessary changes to the FSW. For example, the new "glass cockpit" recently discussed here on Slashdot: when these upgrades were designed, they chose to design the interface to the new display modules to exactly mimic the interface to the old intruments. In other words, they are true plug-and-play replacements; one significant reason for this was so the flight software didn't have to be modified.
Likewise, people often ask why the shuttle continues to use such antiquated General Purpose Computers: slow, 16-bit machines designed back in the seventies. There are many reasons, but a big reason is that new hardware would almost certainly require massive changes to the flight software. And rewriting and recertifying all that software would be a huge task. The current FSW works reliably; if it ain't broke...
Huzzah! As I type, we just launched Atlantis. Go, baby, go!
Does anybody remember the Spam Cam? These guys wanted to know whether Spam (the meat-flavored lunch product) was organic. So they opened a tin, set that Spam brick out on a plate, and posted daily pictures. I'm not entirely sure what, if anything, that they proved. Gray and green mold grew all over the thing, and it appeared to change shape somewhat. Also, according to the Spam Cam operators, it was extremely stinky.
Later they set out other food products to rot, but never again did they achieve the touching poignancy of that wonderful mold-covered brick.
As one of those who was outspokenly critical of Slashdot in this matter, let me be one of the first say that I think Hemos, Katz, and company are doing the right thing here. In particular I'm happy to see that they weren't concerned so much with the nuts-and-bolts legality of publishing the book, as with the larger question of whether it was the right thing for them to do. If they had wanted nothing more than to keep the lawyers happy, they could have published anyway but that would have alienated many of the Slashdot faithful and would have been contrary to the spirit of the "little guy" that Slashdot so often seeks to defend.
I know this decision can't have been easy for Slashdot. In e-mail exchanges with Hemos and Jon Katz following my "Slashmouth" editorial, I came to appreciate the deep commitment they have to the people that Hellmouth is by and about. I know that they wanted the Hellmouth stories to reach as many people as possible, and I recognize that a book would probably have reached more people than a serialization will. But they also care about doing the right thing, and in this compromise I think they have done that.
It still remains for Slashdot to clarify, for the future, what their exact stance is on copyright issues. Who posts here, and what does "ownership" refer to? I have faith that they will answer these questions too, and that most Slashdot users will be happy with their answers.
I hate it when I click on a hyperlink on somebody's web site and I find it popping up a new window. 99% of the time, it's unnecessary except to satisfy the ego of someone whose page is so important they want it to remain onscreen while I visit the linked-to site. This is pure arrogant self-indulgence and that goes for Zeldman too.
Listen, you "gods" of website design, and listen well: if I want a new window, I'll pop it up myself! I appreciate it that you know so much more about the Internet than I do, and that I'm fortunate to have found a web site that is willing to help me so much by popping up new windows... BUT NO THANKS! I know when I want a new window popped up, and I know how to work my browser well enough do so. So leave my windows alone! Your web site isn't so fscking special that it deserves to create its own new kind of segregation. SO CUT IT OUT!
Slashdot Mirror
it does kinda make sense that they could supply a software patch which would check to see if there was faulty memory and, if there was, make an alteration to the OS to stop it from accessing that area of memory.
Read the TRG FAQ. The patch has nothing to do with accessing "bad" areas of memory; in fact, the corruption doesn't even occur when the OS is running! The problem is the memory chip's faulty implementation of self-refresh mode used when the Palm is asleep. The patch changes the refresh mode used.
--Jim
speed vs. reliability...
Speaking of reliability, what's been happening to Slashdot lately? I keep getting lots of Apache errors claiming the server is misconfigured. Reloading usually clears the error and loads the page. Sometimes Slashdot isn't responding at all. Last week response was so slow that I thought maybe another DoS attack was underway. What's the deal, Rob?
--Jim
Hmm... look at the dates in these images:
% exif-date *.JPG
Fri Jan 31 00:00:35 1997 DCP00307.JPG
Sun Jun 25 07:05:36 2000 DSC_0265.JPG
Sat Jun 24 13:37:56 2000 DSCN0518.JPG
Come on guys, set those clocks right so your Exif tags mean something!
More details:
% ~/projects/exif/exif-tools-0.0.6/dump-exif -a *.JPG
DCP00307.JPG:
EXIF tags are in big endian byte order.
IFD at 8 has 10 entries:
ImageDescription:
Make: Eastman Kodak Company
Model: DC210 Zoom (V03.10)
Orientation: 1
XResolution: 216/1
YResolution: 216/1
ResolutionUnit: 2
YCbCrPositioning: 1
Copyright:
ExifOffset: 374
IFD at 756 has 12 entries:
ImageWidth: 96
ImageLength: 72
BitsPerSample: 8, 8, 8
Compression: 1
PhotometricInterpretation: 2
StripOffsets: 928
SamplesPerPixel: 3
RowsPerStrip: 72
StripByteCounts: 20736
XResolution: 72/1
YResolution: 72/1
ResolutionUnit: 2
IFD at 374 has 17 entries:
ExposureTime: 0.0333333 S
FNumber: 40/10
ExifVersion: 48 49 49 48
DateTimeOriginal: 1997:01:31 00:00:35
ComponentConfiguration: 1 2 3 0
CompressedBitsPerPixel: 0/0
ShutterSpeedValue: 1/32 S
ApertureValue: 40/10
BrightnessValue: 30/10
ExposureBiasValue: 0/10
MaxApertureValue: 400/100
SubjectDistance: 0/0
MeteringMode: center-weighted average
LightSource: Auto
Flash: 1
FocalLength: 44/10
MakerNote:
DSC_0265.JPG:
EXIF tags are in big endian byte order.
IFD at 8 has 10 entries:
ImageDescription:
Make: NIKON CORPORATION
Model: NIKON D1
XResolution: 300/1
YResolution: 300/1
ResolutionUnit: 2
Software: Ver.1.05
DateTime: 2000:06:25 06:05:36
YCbCrPositioning: 2
ExifOffset: 240
IFD at 1126 has 7 entries:
Compression: 6
XResolution: 300/1
YResolution: 300/1
ResolutionUnit: 2
JpegIFOffset: 1232
JpegIFByteCount: 5281
YCbCrPositioning: 2
IFD at 240 has 26 entries:
ExposureTime: 0.004 S
FNumber: 80/10
ExposureProgram: 2
ExifVersion: 48 50 49 48
DateTimeOriginal: 2000:06:25 06:05:36
DateTimeDigitized: 2000:06:25 06:05:36
ComponentConfiguration: 1 2 3 0
CompressedBitsPerPixel: 2/1
ExposureBiasValue: 0/6
MaxApertureValue: 36/10
MeteringMode: multi-segment
FocalLength: 240/10
MakerNote:
unknown tag 9286
unknown tag 9290
unknown tag 9291
unknown tag 9292
FlashPixVersion: 48 49 48 48
ColorSpace: 1
ExifImageWidth: 2000
ExifImageHeight: 1312
ExifInteroperabilityOffset: 1096
SensingMethod: 2
unknown tag a300
unknown tag a301
unknown tag a302
DSCN0518.JPG:
EXIF tags are in little endian byte order.
IFD at 8 has 11 entries:
ImageDescription:
Make: NIKON
Model: E950
Orientation: 1
XResolution: 300/1
YResolution: 300/1
ResolutionUnit: 2
Software: v981-77
DateTime: 2000:06:24 12:37:56
YCbCrPositioning: 2
ExifOffset: 284
IFD at 792 has 6 entries:
Compression: 6
XResolution: 300/1
YResolution: 300/1
ResolutionUnit: 2
JpegIFOffset: 2036
JpegIFByteCount: 4006
IFD at 284 has 24 entries:
ExposureTime: 0.0714286 S
FNumber: 29/10
ExposureProgram: 2
ISOSpeedRatings: 0
ExifVersion: 48 50 49 48
DateTimeOriginal: 2000:06:24 12:37:56
DateTimeDigitized: 2000:06:24 12:37:56
ComponentConfiguration: 1 2 3 0
CompressedBitsPerPixel: 4/1
ExposureBiasValue: 0/10
MaxApertureValue: 26/10
MeteringMode: multi-segment
LightSource: Auto
Flash: 0
FocalLength: 98/10
MakerNote:
unknown tag 9286
FlashPixVersion: 48 49 48 48
ColorSpace: 1
ExifImageWidth: 1600
ExifImageHeight: 1200
ExifInteroperabilityOffset: 886
unknown tag a300
unknown tag a301
Well, I'm glad that we've started looking before a disaster, unlike 'Rendezvous With Rama'." Or Lucifer's Hammer.
The people of Earth were actually pretty lucky in those books. Humanity survived in both -- pretty well in Rama, not as well in Hammer. But they survived. It wouldn't take too big an asteroid to kill us all, so don't go kidding yourself that those books describe worst-case scenarios. They don't.
--Jim
What is the origin of the Pan-Galactic Gargle Blaster, and how would you make one on Earth? I need to know.
Since you can't make one on Earth (the treaties could probably be ignored, but the laws of physics are going to be a bit tricky) you need to find a substitute. I've found the Zombie to be a crude but effective substitute. Some nice fruit juice, lots of Rum. YMMV.
Or you can always fall back to gin-and-tonics, which are available in every culture.
--Jim
If you want to see something really cool, go unitedspacealliance.com or spaceflight.nasa.gov during a shuttle mission. You can see live orbiter telemetry -- not just some state vector-base orbital predictor, but actual telemetry. The applet even uses the same telemetry protocol as is used within mission control.
--Jim
Actually, wouldn't it depend on whether Stephen had the GPL virus when Lucy was concieved? If his DNA was Proprietary at her conception, then her DNA should be Propriatry too, regardless of Stephen's current License state. What about Catherine's DNA? Does Lucy automatically inherit Cross-Licensing Rights from both parents? What if Catherine's DNA is under the BSD license? And does Lucy have to sign an NDA when she reaches legal age, or does she automatically receive her own License? Which license? Does she get to choose her own? Since her DNA is unique (though a Derivate Work of both parents') does she retain an Exclusive License? Is it Transferrable? Is it Revokable? Inquiring minds want to know.
--Jim
The Dr. Bechly article was already done... over a week ago... maybe if you read articles, instead of bitching so much, you'd know this.
Maybe you should read the articles. Dr. Bechly's original article, which you linked to, was his original money offer. What this slashback contain, and what the first poster said should be a standalone article, was Dr. Bechly's withdrawal of the original offer. Read both and you'll see the difference.
To put this post back on-topic, I enjoyed reading Bechly's withdrawal of the offer, but I agree that it should have been an article of its own. Dr. Bechly's original offer was deemed significant enough that it was posted standalone. Surely today's text, including the interesting (and controversial?) issues raised, deserve the same consideration. Today's post was not only long enough to stand on its own, but the subject deserves its own discussion space, separate from the unrelated threads that will turn up here because of the other slashback topics.
--Jim
Actually, I keep 2 sets of batteries and a charger handy for my Quicktake - it works pretty well for a low-end camera like that one. But for the mass market to take off, we need battery life comparable to a heavily used conventional camera, where you drop a new photo lithium battery in it every few months and then shoot away. Then you only need one spare in your pack, and if it dies you can replace it at any store.
I use three sets of batteries -- typically one set of NiMH cells in the camera, the other NiMH set in the charger, and a pack of Lithiums in the camera bag as my emergency backups. Lithium cells last a long time in a digicam. They're expensive, but they have a long shelf life (on the order of years) so they make great spares.
Your comments about conventional camera power management are right on the mark -- it's something we shouldn't have to worry about. But I'm willing to put up with it for the benefits of my digital camera.
--Jim
This sort of thing has been discussed repeatedly and at length in the Risks Digest. You guys do read the Risks Digest, don't you?
The Risks Digest is more verbosely known as the Forum On Risks To The Public In Computers And Related Systems, ACM Committee on Computers and Public Policy, Peter G. Neumann, moderator. It's a great and fascinating thing to read; it covers almost any topic even tangentially related to the risks of using computers and digital systems, including privacy issues, Y2K issues, software in critical systems, encryption policy, etc., etc. It is known on usenet as comp.risks, and is also available via e-mail. It's an old forum; in the online archives you can read discussions following such famous events as the loss of the Shuttle Challenger and the Robert Morris Internet Worm. Highly recommended reading for anyone making software.
Also recommended are the Privacy Forum and the Computer Privacy Digest.
--Jim
Unfortunately, those cameras cost about $1000, and you still get crappy battery life.
Get a set of 1600 mAH NiMH rechargeable batteries, minimize your use of the LCD screen (if possible), and you'll get reasonable battery life. With my Kodak DC290, I can take enough high-resolution photos to fill my 64MB CF card (about 100 photos at 1792x1200) using a freshly charged set of NiMH AA cells. I've also run some extremely long time-lapse photos on a single set of batteries: one low-res photo per minute for 5 hours.
I'm not saying that digicams don't suck power -- just that it's a manageable problem.
--jim
Not really an easter egg, because it was advertised on the box, but getting into it was just like any "real" easter egg... The Sega Genesis version of Pitfall Mayan Adventure contained an entire, fully playable, copy of the original Activision Pitfall game for the Atari 2600. To get into it, you had to play to a certain point in the game then do something particular. I forget the exact incantation, but it was really cool to see an old game entirely embedded inside a modern game.
--Jim
Ah, and the old 0.999999999... thing
Wow, so many posts over a simple summation of an infinite series. I wonder what this crowd would do with the old "Monty Hall" problem?
--Jim
Arguments about alcoholism can be backed up with statistics, medical evidence, and other objective data. But ethics are slippery concepts must be considered in light of the reputation of the presenter. If John Wayne Gacy tells me that murder is wrong, I'm going to laugh at him even though he's right. However, if he tells me to destroy criminal evidence, not just hide it, I can consider him an authority on the matter. Maybe in the academic world of Rhetoric you are right, but in this argument, Bertrand Meyer does not have a reputation (with me) that makes his arguments persuasive.
Besides, I read his article. He doesn't get it.
Meyer's assertions about C versus OO programmers were not about using object-oriented languages; they were about discipline. If Meyer had said "avoid undisciplined programmers" I would have no beef with him, but he said "avoid C hackers" then offered up a bunch of unsubstantiated reasons why C hackers == undisciplined programmers. It was, as Robert Martin said, bigotry, and it was not ethical.
--Jim
First, attacking the author is not a valid way to attack an argument. The arguments in the article should be considered independently of the author.
Bullshit. The qualifications of the author to write about subject X are just as important as what the author says about subject X. If I think Bertand Meyer has expressed unethical positions in the past then I can hardly respect his present position on Ethics. What would you think of an essay entitled On Defending Faith and Fidelity in the Institution of Marriage when you learned that its author was named William Jefferson Clinton?
Second, criticising a programming language, and by extension those who use those programming languages, is hardly a profoundly unethical thing to do.
Meyer wasn't criticizing a programming language; he was criticizing the people who had used that language. There's a huge difference.
--Jim
I'm not sure Bertrand Meyer is someone we should be listening to on matters of ethics. In his book Object Success Meyer expressed what I find to be an extremely unethical position when he expressed the opinion that C (and presumably C++) programmers, having learned too many bad habits, shouldn't be considered for "real" OO development projects. Hiring managers should look on them with suspicion, he suggested. In spite of his weasel words about "human betterment", I find this to be little more than an expression of prejudice about C/C++ programmers, and I find it unethical in the extreme.
Robert Martin, of Object Mentor, wrote a nice rebuttal to Bertrand Meyer, which he posted to comp.object and comp.lang.c++, among other Usenet groups.
--Jim
The project that I thought you might be interested in is the development of a space shuttle flight computer emulator for linux described here.
I've seen that project description before, because I wrote it. I'm very familiar with the GPCE project because I'm the principal author of the C++ version. Unfortunately, none of our Dual partners in academia wanted to tackle the conversion of GPCE to little-endian architectures, so for now we can't run on Lintel systems.
--Jim
Want to know what a Shuttle GPC looks like? Check outa o/STS39/10064134.htm.
http://www.ksc.nasa.gov/mirrors/images/images/p
--Jim
Actually, AFAIK, the main reason is that old 386s are tested, tested and, once more, tested for space use.
You're thinking of the PGSCs, the IBM Thinkpad laptops that are carried onboard to help the crew do various non-critical tasks, usually (always?) related to payload operations. These are indeed old 386-based machines, radiation-hardened but still susceptible to crashes related to bit errors in RAM. They run Windows 95, so obviously they aren't used for critical ops. (BTW, linux has been run onboard too.)
The GPCs (General Purpose Computers) that run the flight software are IBM AP101-S computers, cousins to the IBM 360/370 architecture machines of the 1970's. The AP101 is a big-endian, 16-bit, 4 MIPS (appr.) machine that can address up to a megabyte (actually 2^19 16-bit halfwords) of memory. It has been extensively tested for space use, as you note, which is another reason NASA sticks with it. An earlier version of this computer, the AP101-B, flew earlier shuttle missions and has been used in military operations like the B-52.
--Jim
I don't work with the FSW people, so I'm not sure about the details of their work flow, but I think it's safe to say that new code goes through several readings, probably both at the pseudo-code and code levels.
Schedule is driven by the planned date for launch, and worked backward from there. For example, if you're going to launch a mission at date L, then the crew begins training at L minus X months, which means that the software has to be ready for the SMS at L minus Y months, which means you have to begin design at L minus Z months, etc. I'm not sure what X, Y, Z and related time deltas are, but I believe they probably start planning at least a couple of years in advance.
--Jim
I happen to work just down the hall from the guys who maintain and upgrade the shuttle Flight Software (FSW), and I can tell you they have a rigorous design, inspection, and test sequence that they go through before they fly new or modified code. The story around here (which I have no reason to doubt) is that the FSW team was one of the first SEI level-5 certified shops in the nation.
I can also tell you that NASA avoids having to make unnecessary changes to the FSW. For example, the new "glass cockpit" recently discussed here on Slashdot: when these upgrades were designed, they chose to design the interface to the new display modules to exactly mimic the interface to the old intruments. In other words, they are true plug-and-play replacements; one significant reason for this was so the flight software didn't have to be modified.
Likewise, people often ask why the shuttle continues to use such antiquated General Purpose Computers: slow, 16-bit machines designed back in the seventies. There are many reasons, but a big reason is that new hardware would almost certainly require massive changes to the flight software. And rewriting and recertifying all that software would be a huge task. The current FSW works reliably; if it ain't broke...
Huzzah! As I type, we just launched Atlantis. Go, baby, go!
--Jim
Does anybody remember the Spam Cam? These guys wanted to know whether Spam (the meat-flavored lunch product) was organic. So they opened a tin, set that Spam brick out on a plate, and posted daily pictures. I'm not entirely sure what, if anything, that they proved. Gray and green mold grew all over the thing, and it appeared to change shape somewhat. Also, according to the Spam Cam operators, it was extremely stinky.
Later they set out other food products to rot, but never again did they achieve the touching poignancy of that wonderful mold-covered brick.
--Jim
Typo. Sentence in last paragraph should read:
Who owns posts here, and what does "ownership" refer to?
--Jim
As one of those who was outspokenly critical of Slashdot in this matter, let me be one of the first say that I think Hemos, Katz, and company are doing the right thing here. In particular I'm happy to see that they weren't concerned so much with the nuts-and-bolts legality of publishing the book, as with the larger question of whether it was the right thing for them to do. If they had wanted nothing more than to keep the lawyers happy, they could have published anyway but that would have alienated many of the Slashdot faithful and would have been contrary to the spirit of the "little guy" that Slashdot so often seeks to defend.
I know this decision can't have been easy for Slashdot. In e-mail exchanges with Hemos and Jon Katz following my "Slashmouth" editorial, I came to appreciate the deep commitment they have to the people that Hellmouth is by and about. I know that they wanted the Hellmouth stories to reach as many people as possible, and I recognize that a book would probably have reached more people than a serialization will. But they also care about doing the right thing, and in this compromise I think they have done that.
It still remains for Slashdot to clarify, for the future, what their exact stance is on copyright issues. Who posts here, and what does "ownership" refer to? I have faith that they will answer these questions too, and that most Slashdot users will be happy with their answers.
Carry on, guys.
--Jim
I hate it when I click on a hyperlink on somebody's web site and I find it popping up a new window. 99% of the time, it's unnecessary except to satisfy the ego of someone whose page is so important they want it to remain onscreen while I visit the linked-to site. This is pure arrogant self-indulgence and that goes for Zeldman too.
Listen, you "gods" of website design, and listen well: if I want a new window, I'll pop it up myself! I appreciate it that you know so much more about the Internet than I do, and that I'm fortunate to have found a web site that is willing to help me so much by popping up new windows... BUT NO THANKS! I know when I want a new window popped up, and I know how to work my browser well enough do so. So leave my windows alone! Your web site isn't so fscking special that it deserves to create its own new kind of segregation. SO CUT IT OUT!
--Jim