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Comment: Re:Amazing (Score 1) 134

by dsmall (#31393996) Attached to: Shuttle Extension & Heavy Launcher Bill Proposed

WindBourne said,
"As such we NEED multiple architectures ... "

      I agree with you. Yet it takes a look at history to see how we got here.

"The above will prevent Congress from doing what it is doing AND will prevent an accident in a rocket from shutting down the entire space program."

Your point here escapes me. Congress controls spending; that's in the Constitution. How could we prevent Congress from doing anything? Recently, Bush's space policy (go back to the Moon, etc) was a good one. However, Congress did not fund it. While I see you faulting "neo-cons", the truth is that the bean counters at OMB (Office of Management & Budget) have control. When the Republicans were in office, no funding. Now the Democrats are in office. No funding.

Obama has had a year to express interest in the space program, or even allocate keep-the-workforce-alive funding.

You wrote, "Nixon killed Skylab because he did not fund NASA properly for building the Shuttle after shutting down Apollo in 1970."

        I came across a detailed and well written history of the Space Shuttle. It's a detailed history of the winding down of Apollo, the effort to fund a Mars mission, a space station, and many different incarnations of the Shuttle. The OMB constantly shows up in these decisions. I highly recommend this history.

  You can find it at:

      http://history.nasa.gov/SP-4221/contents.htm

As an example, here is a quote from that history concerning Nixon's decision to approve the Shuttle:

"Why, finally, did Nixon decide to build the Shuttle? One must not underestimate the tendency of the federal government to look after its own; few major Washington programs reach an end, to vanish into the night. Nixon had no wish to shut down piloted space flight; he wanted to keep it alive. He also was concerned over aerospace employment. Yet he could have addressed such issues with nothing more than Big Gemini riding atop a Titan III-M, to fly occasionally and show the flag.

The key to the Shuttle was its well-founded prospect of low cost and routine operation. This promise did not rest on the cost-benefit studies of Mathematica, which the Flax Committee largely refuted and the OMB rejected out of hand. Rather, it rested on technical developments: automated onboard checkout, reusable thermal protection, rocket engines with long life. No OMB internal memo or White House report ever denied this promise; only experience would do that, years later. The Shuttle thus could find its way to approval, within a nation and government that remained willing to embrace the new."

Thanks,

David Small

Comment: Re: So what? Okay, here's "what". (Score 1) 496

by dsmall (#30267416) Attached to: Microsoft's Top Devs Don't Seem To Like Own Tools

... The discussion is wobbling around Microsoft's coders and tools and why machine code isn't necessary anymore ...

      And here we were just discussing yet-another-chip-bug in an Intel chip which affects, as they say, 'three guesses and two don't count', yes, a Microsoft product. (Remember? Something about timer interrupts which can get stepped on by other timers, hanging the system. It's a known bug. In fact, there's 69 pages of known bugs in the i7 chip "errata" sheet.)

          I would (gently) ask this: Which programmer is more likely to make the mistake of relying on this timer:

Programmer A, who learned C++ in college and is wizard at high level abstraction, or,

Programmer B, who has gone down to the bare metal and programmed chips?

Who is more likely to actually read the errata sheet that says, 'Don't use this frickin' timer'?

          My answer is that people who have read chip datasheets (and errata sheets!) before are far more likely to read them again before trying to use that (broken) timer on the i7 chip.

          Something else which really troubles me is how hard this bug may have been to find. Windows crashed? And the processor hung, not "leaving any tracks" in memory? I will just mention that this has happened to me a time or two (*cough, cough*). Just realizing it was a seperate and new bug was probably awful.

          Now imagine you're the poor slob at Redmond who has to fix this! You're told: "Windows Server crashes. Fix it." What are you gonna do? If you don't have an in-circuit emulator that can "watch" the crash, you are in for some real debugging hell. I've been there.

          Someone had to fix this problem and make a "hot patch". What language do you think they used, APL?

          Someone still has to read the datasheets that chip manufacturers put out, in particular the North/Southbridge chipsets. The Linux people are getting really good at it.

          People overclock RAM. They have to understand enough about SDRAM to do that. That's machine level clock-cycle stuff. They also overclock CPU's and use amazing cooling systems (anyone for liquid nitrogen?).

          Back When Dinosaurs Ruled The Earth and I was in college, I was told that assembly was on its way out and a High Level Language, PASCAL, was going to be the standard. This was 1976-1980.

          It's been awhile since I've even seen a PASCAL compiler, but the Visual C debugger shows me RAM, disassembly of opcodes, and all the Intel registers step-by-step ... and man, does it ever help to know what the hell each assembly instruction does.

          There's a time and place for high level abstraction. And there's a time and place for talking to the chips. I suspect that people's opinions about this are something like the C "brace wars" (the "proper" placement of "{}".)

          Enjoy --

          Dave Small

Comment: Re:Isn't it really a bug in Windows Server? (Score 1) 154

by dsmall (#30259598) Attached to: Microsoft Advice Against Nehalem Xeons Snuffed Out

      Tom, you might want to look over the
"Intel (r) Core (tm) i7-900 Desktop Processor Extreme Edition Series and Intel (r) Core (tm) i7-900 Desktop Processor Series".

      It has around 69 pages of ... well, I'll let Microsoft say it ... the processors "may contain design defects or errors known as errata..."

      It's dated November 2009.

      Here's a URL:
              http://download.intel.com/design/processor/specupdt/320836.pdf

          Thanks, Dave

Comment: Re:and NASA (Score 1) 165

by dsmall (#29427449) Attached to: First Private Manned Orbital Flight Announced

Rather than "hate" or "like" NASA, there's a very well written history of how Apollo was compromised (Apollo 18-20 were cancelled), and how the Shuttle ended up with solid rocket boosters, at: http://history.nasa.gov/SP-4221/contents.htm .

It boils down to: This was what NASA could do with the money given them by the OMB (Office of Management and Budget).

I found this process to be quite interesting.

From a historical point of view, history seems to be repeating itself. Another "outside" committee has looked into NASA's plans and other options. The committee has priced the options for lowest possible, plod along, and even (remarkably) do something worthwhile.

I assume "lowest possible" will be picked.

I recommend the above hyperlink to anyone.

Thanks,

      Dave

Comment: Re:Did someone say "programmable platforms"? (Score 1) 580

by dsmall (#29362131) Attached to: Apple Pulls C64 Emulator From the App Store

...quote from parent

"However, in these modern times with object-oriented multithreaded programming, BASIC is kind of a throwback, don't you think?"...

          I would say that different computer languages tend to have different strengths. People are different and they naturally gravitate to different languages, over the dead bodies of their teachers, but it remains true. Knowing several computer languages never hurt anyone. And I'll happily mention that BASIC really does have some strengths. No, I don't think Linux should be written in BASIC. But --

          I've found over time, that for me, BASIC can be really quite useful for whomping up little things, utilities that I need "Right Now, Just This Second". The syntax is friendly and easygoing, and it doesn't throw "avalanche fits". And if I mess up a line and something is wrong, figuring out what's wrong is not an exercise in puzzle solving, (not that I'm referring to "Macho C Coding" or anything [dark muttering] ).

          Basic's fast enough for a lot of things. And I should mention that XBASIC, over at Sourceforge, has an astonishing, superb compiler that makes very, very fast 80x86 code indeed. If you'd like a pleasant surprise, give it a try.

        I would say there's a place for BASIC. Don't underestimate the people how many people really like it. Possibly we should be dragging them, kicking, screaming, their fingernails digging into the wood, into C++ classes.

        But possibly BASIC is all they have time to learn, and all they really -want- to learn, about computers. They may be heathens, but they are also programmers.

        These are just my thoughts. Feel free to disagree with me; I welcome thoughts. I clearly learn the most from people who disagree with me!

        Thanks,

        David Small
davetracer at-sign aol DOT com

         

Comment: Re:Typeset but not printed (Score 1) 271

by dsmall (#29096405) Attached to: The Best and Worst Tech-Book Publishers?

I've had technical books published by various publishing houses.

What troubles me these days is seeing other author's books being scanned in and put up for download as PDF's up on the Net.

I have no problem with open-source programming if the programmer wants to.

      But I think most programmers would be rather annoyed to find their source code published to the Net without their permission, and without any attempt to get their permission.

Authors feel the same way. Writing a book is generally a hell of a lot of work.

    -- thanks,

      Dave Small

Comment: A lot of zeros (Score 2, Insightful) 575

by dsmall (#28778625) Attached to: First New Nuclear Reactor In a Decade On Track

To me this seems a pretty easy answer once you look at the raw numbers.

http://en.wikipedia.org/wiki/Uranium-235 shows that when one atom of U-235, once fissioned, releases 202.5 MeV of heat. That's 202,500,000 electron volts, a.k.a., one huge amount of energy.

An atom of carbon when burned (C + 2 Ox->COx2) releases a few electron volts of energy and gives us carbon dioxide, which is said to be a "greenhouse gas". (I'm not debating that point).

Let's just do it with money, okay?

Hold an atom of carbon in one hand. Hold an atom of uranium in the other hand. The carbon's worth a few dollars. The uranium's worth Two Hundred Million Dollars. Which one do you pick? If you pick uranium, you just hit the Lotto Jackpot!

Bear in mind that you have to get enough of either to meet the energy needs of the country, and it's very hard to get enough coal, and much easier, by a factor of two hundred million, to get uranium.

      Jimmy Carter made the unfortunate decision (funny how those words appear next to his name) not to include used fuel rods in reprocessing. There's a lot of energy there awaiting.

I think what we ought to do as a country is swallow some pride, go to France, which gets about 80% of its energy from nuclear, and say, "Obviously you have a well debugged design. Help! Show us how to do it!" The French do it right. You know how useful debugged code is.

        Thanks,

        Dave Small

Comment: Re:bogus rationalizations (Score 1) 199

by dsmall (#28076803) Attached to: Obama Taps Charles Bolden To Lead NASA

This is terribly sad.

This is the end of Manned Space Flight for the United States.

If you, or your children, want to see the launch of a manned American bird, you'd better do it immediately, in the remainder of 2009 or 2010. You have nine Shuttle launches left.

NASA has been promised funding sufficient for nine more Shuttle missions to finish the ISS, and that is all. (2009 & 2010). This is essentially funding for the coffin and headstone.

One year from now, we will be back to 1957. The Russians will still have their heavy-lift rockets and Soyuz capsules, and we won't have anything. We'll have to beg/buy rides from Russia to get to the ISS. Should the Russians decide they're not in the mood, they can easily say: "And what are you going to do about it?".

The Russians do not have a good "Partners in Space" history. Remember when the ISS was very nearly lost to [Russian] computer problems, the Russians were swift to blame the Americans for "bad power". When the Soyuz's explosive bolts failed, the Russians blamed the ISS for mysterious "plasma discharges" that, somehow (don't ask me how) damaged explosive bolts.

Now NASA is trying to build its "Ares-1" rocket. Two stages. Its lower stage is a Shuttle SRB (Solid Rocket Booster) with an extra solid segment, which means higher pressures, more joints, and this time the vibration is directly transmitted to the backs of the crew.

(I wish someone would tell me why we're not just using the Saturn V main booster technology for the first stage. It has the advantage of being repeatedly tested and it works. Is it just too easy or something?)

It's revealing to see what former NASA officials say when they are not muzzled anymore:

        Former NASA Administrator Mike Griffin said in a recent speech the projected funding shortfalls threaten America's leadership in manned space flight.

        "In a democracy, the proper purpose of the OMB (Office of Management and Budget) is not to find a way to create a Potemkin Village at NASA. It is not to create the appearance of having a real space program without having to pay for it. It is not to specify to NASA how much money shall be allocated for human lunar return by 2020. The proper purpose of the OMB is to work with NASA, as a partner in good government, to craft carefully vetted estimates of what is required to achieve national policy goals. The judgment as to whether the stated goals are too costly, or not, is one to be made by the nation's elected leadership, not career civil service staff.

        No one can wrest leadership in space from the United States. We're that good. But we can certainly cede it, and that is the path we are on."

Something like the Ares-1 design has happened before; see the history of the Space Shuttle:

http://history.nasa.gov/SP-4221/contents.htm

You will find that what Congress/OMB and Obama are doing ia just about precisely what Congress/BoB and Nixon did.

Funding was cut right through the fat, muscle, and into the bone, and the only way NASA could figure out to launch anything was using solid rocket boosters (SRB's), which add significant vibration and which cannot be throttled, or switched off and reignited. Many engineers left NASA when the decision to use SRB's came down.

A stunning quote from one Douglas Cookie, 'Associate Administrator for the Exploration Systems Mission Directorate at NASA HQ', is:

      [Cooke] said the biggest single reason he has favored Ares 1 over competing designs is _crew safety_.

      "That's in part due to the Ares 1 first stage, an extended five-segment shuttle booster. Two four-segment boosters are used for every shuttle flight and in 125 missions to date - 250 booster flights - only one booster has ever failed, the one that doomed Challenger.

        "I personally believe the risk is lower for the crew on this vehicle and that to me is the bigger of the discriminators," Cooke said.

          I have news for Mr. Cooke. Many SRB's showed blow-by through the O-rings. Some came within a few seconds of a loss of vehicle. This showed something was very wrong, but NASA began to literally "normal-ize" it; since nothing awful happened, blow-by began to be considered "normal", or at least, "tolerable". The Morton Thiokol engineers were worried sick about it. NASA got "Go Fever" with the Challenger launch and there was enough blow-by to damage the vehicle, and good-bye. And, actually, the two SRB's survived the loss of the Challenger and had to be destroyed by the range safety officer, so he's wrong twice.

      NASA also continued to see damage to the heat shield tiles, and again, "normal-ized" it, until a hit on the leading edge of a wing killed Columbia. NASA engineers were concerned about possible damage and asked for photographs to be taken, possibly from DoD sources, but NASA management ... could that have been Mr. Cooke? ... turned them down.

          Finally, now it's coming out that the Ares SRB has big vibration problems. Quote, "NASA admitted that this problem is very severe, rating it four out of five on a risk scale". I wonder if Mr. Cooke was aware of this when he said that "crew safety" was his primary concern.

          I think Mr. Cooke ought to be put onboard one of the early Ares test flights, with all sorts of sensors wired up to him, to see the effect on humans of severe vibration. (There is no need for brain wave sensors, as there are none present.)

          I was born in 1958, as was NASA. I remember that "Star Trek" was on TV when we were launching Gemini and beginning to test Apollo.

          Stripping NASA of $3 billion so that it can be given to political groups, for example, to jigger the 2010 Census, is in several ways a terrible waste of needed money. This is short sightedness at its worst.

        Thanks,
          Dave

Comment: Or just put on Neil Young Live. (Score 1) 233

by dsmall (#28013199) Attached to: Why Programming Rituals Work

Sure, I "get" the rational answers about clearing your mind and letting your subconscious work on problems and stuff. Then there those other problems. When the network is down for no discernible reason. When it's a "bad day".

Here's a very weird bit of magic to know about. I know how weird this is, but it works. Oh, ye Gods, does it work! I have come to absolutely hate doing it, but, it just [dammit] works.

You won't believe it until you try it, and then you, too, will (a) hate it and (b) see it work.

Get Neil Young's "Live Rust" album. It's live, so studio engineers haven't fixed up all the mistakes.

Instead of hitting notes, Neil... shotguns notes, all around them. For some awful reason he writes songs on the very wobbling top edge of his vocal range. He's just one of those people who should be banned from singing the songs he writes.

The lyrics are really depressing. Cortez is massacring the Mayans. We got Mother Nature on the run. It's better to burn out than to fade away. And his favorite song topic, band people dying of overdoses: Every junkie's like a setting sun. Heard that he died, out on a mainline.

(Neil has not made a 2+2 = ? connection yet. If I were in his band and I had to listen to him every night, both (1) heroin and (2) death would look pretty good.)

I discovered this by accident while coding keyboard and mouse drivers. They were extremely hard. I was desperate. I saw one of those skiier T-shirts that says, "No Pain, No Gain", and I logically inverted it to "If Pain, Gain". I looked through my record albums to find True Pain and there was Neil. Put it on side 3 Repeat and started coding.

Six plus hours and 1,500 lines of 68000 assembly later, I was done coding. I finally ran the AS68 assembler on it, and it said back to me: 0 Errors.

YouHaveGotToBeKiddingMeTheresAlwaysErrors. TyposIfNothingElse.

Floating in a sea of shocked surprise, I linked it and ran it, and my God, the keyboard and mouse code worked the first time.

This does not happen. As Luke Skywalker put it, "That's Impossible!" I've been terrified to touch that code.

The Neil effect has continued to work.

Last time I used Neil was on a laptop that WinXP would not install onto. Tried 3 times, the install hung each time. The guy's son Anthony said, "Dave, why aren't you playing Neil Young?" Good point. I put it on. I explained this to the guy. He looked at me like I was insane. I said, "You don't believe it right now. That's okay. You'll see it. Then you'll believe." With Neil wailing away about his first cigarette, and changing absolutely nothing, the XP install went without a hitch.

All I can say is I tripped over it by accident, I don't know how it works, but damn!, it does work. And you'll start to dislike that album as much as I do. Maybe the cost is listening to something you really don't care for. (I should try rap!)

I'm not making this up.

  -- Dave Small

Space

+ - NASA budget cut $3 billion

Submitted by
dsmall
dsmall writes "CBS NEWS Coverage of Breaking Space News
Posted: 4:30 PM, 5/8/09

By William Harwood
CBS News Space Consultant

Changes and additions:

04/15/09 (12:45 PM): Station crew says lab ready for six full-time crew members
05/07/09 (06:55 PM): Obama orders independent review of manned space operations; NASA 2010 budget unveiled
05/08/09 (04:30 PM): Reeling from projected budget cuts, NASA braces for manned space flight review

=================================

4:30 PM, 5/8/09, Update: NASA braces for manned space flight review

Reeling from projected budget cuts totaling more than $3 billion through 2013, NASA managers and engineers working to build a post-shuttle rocket system for an eventual return to the moon are bracing for a critical review ordered by the Obama administration that could set the agency on a different course.

The chairman of an independent review panel charged with evaluating NASA's post-shuttle manned space program said Friday he will bring an open mind and "go where the facts lead" in assessing the technical and economic feasibility of the space agency's current manned space program.

Norman Augustine, former chief executive officer of Lockheed Martin Corp., said the Review of United States Human Space Flight Plans Committee also will assess alternatives, including different rocket systems and alternative targets for exploration. The team's report is expected by August.

"We are planning to spend billions of dollars on the human space flight program and it's wise to be sure we're spending that the way we should," he told reporters in a teleconference. "New information becomes available all the time. And similarly, we have a new administration and it would probably be imprudent on their part not to examine this major of a program to be sure such a long term undertaking is still on a course that makes sense to them."

The cost of NASA's manned space program — and ongoing efforts by the Office of Management and Budget to cut spending — is at the heart of the review, announced Thursday when the Obama administration's fiscal 2010 budget request was unveiled.

"I think what it boils down to is we're being told there's no sense in being unrealistic and putting together a program that can't possibly be afforded, and we've been given some guidance," Augustine said. "I think one of the chronic problems NASA's encountered over the years has been that it usually had more programs than it had money. That can be dangerous when you're doing something as difficult as NASA does.

"So as we go through this evaluation, if we were to find there were reasons the budget didn't make sense in any way, I can assure you we would not be bashful about pointing that out, and I suspect the administration would want to know that anyway."

The Obama administration is asking Congress for $18.7 billion in funding for NASA in 2010, a watershed year for the civilian space agency as it tries to complete assembly of the International Space Station and retire the space shuttle fleet after just nine more flights.

NASA is designing a new rocket, called the Ares 1, and an Apollo-style Orion capsule to replace the shuttle, but the new system will not be ready for routine use until 2015. During the five years between the shuttle's retirement next year and the debut of Ares 1/Orion, NASA will be forced to buy seats on Russian Soyuz rockets to get U.S. astronauts to and from the space station.

NASA's long-range goal, set by the Bush administration, is to return to the moon by 2020, using Ares 1/Orion spacecraft to carry astronauts to orbit and then new heavy-lift Ares 5 rockets to boost the astronauts and lunar landers to the moon. The new rocket systems are the central elements of what NASA calls the Constellation program.

But funding has been a critical issue from the beginning. Congress and the Bush administration, which put NASA on its current course, did not provide the funding necessary to significantly reduce the gap between shuttle retirement and first flight of Ares 1/Orion.

The Obama administration's 2010 budget includes a near-term funding boost of $630 million for Constellation, thanks in part to about $1 billion routed to NASA as part of the economic Recovery Act.

But the administration's predicted budgets through 2013 show an overall cut of $3.1 billion for the exploration systems directorate in charge of Constellation, cuts that have sent shock waves through the NASA community.

"That's the real story," a senior space manager, who asked not to be named, said of NASA's Thursday budget briefing. "It's like that Sherlock Holmes thing, the real story is the dog that didn't bark in the night. ... If the three-plus billion dollars in the out years, if that cut stands, then there's no moon by 2020 and maybe none at all."

NASA officials said Thursday the budget numbers may change depending on the results of the Augustine review. But the agency turned down a request Friday for an interview with Jeff Hanley, Constellation program manager at the Johnson Space Center in Houston, to discuss the potential impacts of the projected cuts.

Against this backdrop, the Obama administration ordered the Augustine review of NASA's ongoing manned space exploration program, prompting speculation that budget pressures could lead to a major change of course. It's not yet known how any such a change might affect the gap between shuttle and any follow-on spacecraft, or whether the moon will even remain NASA's primary target.

"I must confess, as an individual I'm not thrilled with the fact that we have a gap," Augustine said. "But we have what we have. ... There are things that could be done, probably, that would shorten the gap, there are some things one might do that would lengthen the gap. But certainly, an objective, I think, of anybody would be to balance the various pros and cons of whatever is proposed against the impact on the gap, among other things, and recognizing that extending the gap is probably not a desirable thing. On the other hand, and I'm not making predictions here because I don't know the outcome, it's not something that's written in stone, either."

John Holdren, director of the White House Office of Science and Technology Policy, said the administration's objective "is to ensure that these programs remain on a strong and stable footing well into the 21st Century, and this review will be crucial to meeting that goal."

An OSTP statement said Augustine's panel will "assess a number of architecture options, taking into account such objectives as: 1) expediting a new U.S. capability to support use of the International Space Station; 2) supporting missions to the Moon and other destinations beyond low Earth orbit; 3) stimulating commercial space flight capabilities; and 4) fitting within the current budget profile for NASA exploration activities."

While the review is underway, NASA was told to continue work on Ares 1/Orion.

Augustine said he planned to assemble a team of experts with a broad range of space experience to evaluate the Constellation program and alternative architectures "both from an economic and a technical standpoint."

"We have a rather short time period to conduct our review, to be completed in August, and because of that we're drawing heavily on prior work and on our own experience as well as analyses ... from NASA and possibly others."

He said the panel's instructions are "to take a fresh, independent look at the human spaceflight program and go where the facts lead. And that's what we'll try to do. Obviously, the U.S. has excelled in the exploration and utilization of space for a long time. It's a source of great pride to our nation as well as, I might say, to myself.

"I also have long believed it should be a balanced program that includes both robotics and human involvement. Our focus will be on the human spaceflight aspect. The president has made rather clear he's very supportive of human spaceflight, he believes it's important from an economic and technical and scientific leadership standpoint. I certainly share that view and I believe this is an important task and I look forward to leading it."

=================================

Quick-Launch Web Links:

CBS News Space Shuttle Status Reports:
http://ct.cbsnews.com/clicks?t=202601711-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5

CBS News Space Shuttle Quick-Look Page:
http://ct.cbsnews.com/clicks?t=202601712-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5

CBS News Breaking Space News Page:
http://ct.cbsnews.com/clicks?t=202601713-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5

NASA Shuttle Web: http://ct.cbsnews.com/clicks?t=202601714-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
NASA Station Web: http://ct.cbsnews.com/clicks?t=202601715-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
Spaceflight Now: http://ct.cbsnews.com/clicks?t=202601716-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
GoogleSatTrack: http://ct.cbsnews.com/clicks?t=202601717-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5

Hubble Space Telescope Background:

HST Overview: http://ct.cbsnews.com/clicks?t=202601718-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
Servicing Missions: http://ct.cbsnews.com/clicks?t=202601719-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
SM-4: http://ct.cbsnews.com/clicks?t=202601720-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
Space Telescope Science Institute: http://ct.cbsnews.com/clicks?t=202601721-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
Hubble Site: http://ct.cbsnews.com/clicks?t=202601722-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
NASA HQ Hubble Page: http://ct.cbsnews.com/clicks?t=202601723-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
Goddard Hubble Page: http://ct.cbsnews.com/clicks?t=202601724-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5
Ball Aerospace Hubble Page: http://ct.cbsnews.com/clicks?t=202601725-f10ca05ebe88ea6189f7f7250b07b818-bf&brand=CBSNEWS&s=5

================================="

Comment: C is real good for machine gunning the foot (Score 1) 612

by dsmall (#27060959) Attached to: Null References, the Billion Dollar Mistake

I tested hundreds of Mac software applications 'Back In The Day'. A bit more than half of all of them banged onto location 0. About 100% of Microsoft Mac apps crashed. This happened to not (immediately) crash the Mac because the Mac just happened to have RAM mapped there, but, since multiple applications were resident in memory, taking turns shooting at 0.Long, "Difficult to debug problems, often not repeatable, soon arose".
[I do love that phrase; it covers so much agony so concisely].

The Mac had a memory heap structure with "handles", which aimed at "pointers", which aimed at "memory blocks". From time to time, just to amuse developers, the Mac would compress memory to get rid of stale stuff. The handles would be updated but, a zero would go into the pointer you were trusting ...

I was busy teaching the Atari ST 68000 computer to be a Mac at the time. The Atari ST had ROM mapped to locations 0-7. It bus-errored every time someone used a Nil pointer. This looked unsolvable unless I wanted to patch two zillion Mac programs.

I finally looked at the problem in a very, very simple manner, and discovered the IW (instruction word) that had caused the crash was on the stack, and the PC (program counter) was a bit past the crash point due to prefetch. A dim flickering flight appeared over my head. What if I "back up" the PC to the Evil Instruction, disassemble it to get its length [I hear you sigh at the thought of writing a disassembler, but I did], advance the PC to the next instruction (so we're just skipping over "the store into 0.Long" here), put all this on the stack, and treat it like a "normal" exception interrupt ... "Return from Exception."

And it worked! The 68000 came back from a crash!

That one thing made all the difference.

To this day I have wondered, though ... if the Atari ST had ROM there ... what happened to all the data written to location 0?

*grin*

David Small

Comment: Re:Transmutation of waste (Score 1) 432

by dsmall (#26678449) Attached to: Fusion-Fission System Burns Hot Radioactive Waste

Well, depending on the reaction (D+D, D+T, T+T), you get different levels of energy, but in general, nearly all of a fusion reaction's energy goes into making very, very energetic neutrons. At above 1 MeV these neutrons can split even "depleted" uranium or U-238. That's why half the energy from a "fusion" bomb is from fissioning the uranium wrapper, and the fission amount has been as large as 7.5 MT (Castle Bravo).

I haven't seen data on what very energetic neutrons do to isotopes like U-233 or other junk left after U-235 fission; that's one detail the article doesn't go into. I'd sure like to know.

Certainly the heat generated could spin a turbine. Which leads me to ask:

"Spent" fuel casks are typically stored underwater for shielding. If they're as radioactive as stated, they really warm the water up. Why isn't this used to generate electricity?

-- Thanks, Dave

I never cheated an honest man, only rascals. They wanted something for nothing. I gave them nothing for something. -- Joseph "Yellow Kid" Weil

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