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How do I change the background color in Unix? The first edition of Unix let programmers call 34 different low-level routines built into the operating system. It's a testament to the system's enduring nature that nearly all of these system calls are still available—and still heavily used—on modern Unix and Linux systems four decades on.
Yet it contained just lines of code at its heart and occupied a measly 16 KB of main memory when it ran. Unix's great influence can be traced in part to its elegant design, simplicity, portability, and serendipitous timing. But perhaps even more important was the devoted user community that soon grew up around it. And that came about only by an accident of its unique history.
The story goes like this: For years Unix remained nothing more than a Bell Labs research project, but by its authors felt the system was mature enough for them to present a paper on its design and implementation at a symposium of the Association for Computing Machinery.
That paper was published in in the Communications of the ACM. Its appearance brought a flurry of requests for copies of the software. S government consent decree that prevented the company from selling products not directly related to telephones and telecommunications, in return for its legal monopoly status in running the country's long-distance phone service. So Unix could not be sold as a product.
With no other channels of support available to them, early Unix adopters banded together for mutual assistance, forming a loose network of user groups all over the world.
They had the source code, which helped. And they didn't view Unix as a standard software product, because nobody seemed to be looking after it. So these early Unix users themselves set about fixing bugs, writing new tools, and generally improving the system as they saw fit. The Usenix user group acted as a clearinghouse for the exchange of Unix software in the United States.
People could send in magnetic tapes with new software or fixes to the system and get back tapes with the software and fixes that Usenix had received from others. In Australia, the University of New South Wales and the University of Sydney produced a more robust version of Unix, the Australian Unix Share Accounting Method, which could cope with larger numbers of concurrent users and offered better performance. By the mids, the environment of sharing that had sprung up around Unix resembled the open-source movement so prevalent today.
Users far and wide were enthusiastically enhancing the system, and many of their improvements were being fed back to Bell Labs for incorporation in future releases. One person who caught their eye was John Lions , a computer scientist then teaching at the University of New South Wales, in Australia. In , he published what was probably the most famous computing book of the time, A Commentary on the Unix Operating System , which contained an annotated listing of the central source code for Unix.
Unix's licensing conditions allowed for the exchange of source code, and initially, Lions's book was sold to licensees. For example, between the release of the sixth edition of Unix in and the seventh edition in , Thompson collected dozens of important bug fixes to the system, coming both from within and outside of Bell Labs.
He wanted these to filter out to the existing Unix user base, but the company's lawyers felt that this would constitute a form of support and balked at their release. Nevertheless, those bug fixes soon became widely distributed through unofficial channels.
For instance, Lou Katz, the founding president of Usenix, received a phone call one day telling him that if he went down to a certain spot on Mountain Avenue where Bell Labs was located at 2 p.
Sure enough, Katz found a magnetic tape with the bug fixes, which were rapidly in the hands of countless users. By the end of the s, Unix, which had started a decade earlier as a reaction against the loss of a comfortable programming environment, was growing like a weed throughout academia and the IT industry. Unix would flower in the early s before reaching the height of its popularity in the early s.
For many reasons, Unix has since given way to other commercial and noncommercial systems. But its legacy, that of an elegant, well-designed, comfortable environment for software development, lives on. In recognition of their accomplishment, Thompson and Ritchie were given the Japan Prize earlier this year, adding to a collection of honors that includes the United States' National Medal of Technology and Innovation and the Association of Computing Machinery's Turing Award.
Many other, often very personal, tributes to Ritchie and his enormous influence on computing were widely shared after his death this past October. Unix is indeed one of the most influential operating systems ever invented. Its direct descendants now number in the hundreds. On the other side are various Unix-like operating systems derived from the version of Unix developed at the University of California, Berkeley, including the one Apple uses today on its computers, OS X.
Had this operating system been available at the time, Linus Torvalds says he probably wouldn't have created Linux , an open-source Unix-like operating system he developed from scratch for PCs in the early s.
Linux has carried the Unix baton forward into the 21st century, powering a wide range of digital gadgets including wireless routers, televisions, desktop PCs, and Android smartphones. It even runs some supercomputers.
By , no fewer than five major lawsuits had been filed. As a programmer and Unix historian, I can't help but find all this legal sparring a bit sad. From the very start, the authors and users of Unix worked as best they could to build and share, even if that meant defying authority. That outpouring of selflessness stands in sharp contrast to the greed that has driven subsequent legal battles over the ownership of Unix.
The world of computer hardware and software moves forward startlingly fast. For IT professionals, the rapid pace of change is typically a wonderful thing. But it makes us susceptible to the loss of our own history, including important lessons from the past.
That effort morphed into the Unix Heritage Society. Our goal is not only to save the history of Unix but also to collect and curate these old systems and, where possible, bring them back to life. With help from many talented members of this society, I was able to restore much of the old Unix software to working order, including Ritchie's first C compiler from and the first Unix system to be written in C, dating from One holy grail that eluded us for a long time was the first edition of Unix in any form, electronic or otherwise.
This was an amazing find—like discovering an old Ford Model T collecting dust in a corner of a barn. But we didn't just want to admire the chrome work from afar.
We wanted to see the thing run again. In , Tim Newsham, an independent programmer in Hawaii, and I assembled a team of like-minded Unix enthusiasts and set out to bring this ancient system back from the dead. We sent out messages announcing our success to all those we thought would be interested.
Warren Toomey teaches at Bond University, in Australia. He was bitten by the Unix bug in while still in high school, when he spent two weeks at the University of Wollongong learning about computers. It turns out that you don't need a lot of hardware to make a flying robot. Flying robots are usually way, way, way over-engineered, with ridiculously over the top components like two whole wings or an obviously ludicrous four separate motors.
Maybe that kind of stuff works for people with more funding than they know what to do with, but for anyone trying to keep to a reasonable budget, all it actually takes to make a flying robot is one single airfoil plus an attached fixed-pitch propeller.
And if you make that airfoil flexible, you can even fold the entire thing up into a sort of flying robotic swiss roll. This type of drone is called a monocopter, and the design is very generally based on samara seeds, which are those single-wing seed pods that spin down from maple trees.
The ability to spin slows the seeds' descent to the ground, allowing them to spread farther from the tree. It's an inherently stable design, meaning that it'll spin all by itself and do so in a stable and predictable way, which is a nice feature for a drone to have—if everything completely dies, it'll just spin itself gently down to a landing by default. F-SAM stands for Foldable Single Actuator Monocopter, and as you might expect, it's a monocopter that can fold up and uses just one single actuator for control.
There may not be a lot going on here hardware-wise, but that's part of the charm of this design. The one actuator gives complete directional control: increasing the throttle increases the RPM of the aircraft, causing it to gain altitude, which is pretty straightforward.
Directional control is trickier, but not much trickier, requiring repetitive pulsing of the motor at a point during the aircraft's spin when it's pointed in the direction you want it to go. F-SAM is operating in a motion-capture environment in the video to explore its potential for precision autonomy, but it's not restricted to that environment, and doesn't require external sensing for control.
While F-SAM's control board was custom designed and the wing requires some fabrication, the rest of the parts are cheap and off the shelf. If you look closely, you'll also see a teeny little carbon fiber leg of sorts that keeps the prop up above the ground, enabling the ground takeoff behavior without contacting the ground. You can find the entire F-SAM paper open access here , but we also asked the authors a couple of extra questions. IEEE Spectrum: It looks like you explored different materials and combinations of materials for the flexible wing structure.
How a new process is created in UNIX? Frequent question: How do I change the shell color in Unix? How is a new child process created in the Unix operating system programming environment? Like this post? Please share to your friends:. Ubuntu is a complete Linux operating system, freely available with both community and professional. Press the Windows logo on your keyboard, or click the Windows icon in the.
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