From time to time we realize that sayings which make sense to us probably will have no meaning for future generations. Two of the examples that spring to mind are “hang up the phone” or in a vehicle you might “roll down the window”. And so is the case for today’s Retrotechtacular. Linux users surely know about TTY, but if you look up the term you actually get references to “Teletypewriter”. What’s that all about?
[Linus Akesson] wrote a fantastic essay on the subject called The TTY Demystified. We often feature old video as the subject of this column, but we think you’ll agree that [Linus’] article is worth its weight in film (if that can be possible). The TTY system in Linux is a throwback to when computers first because interactive in real-time. They were connected to the typewriter-mutant of the day known as a teletype machine and basically shot off your keystrokes over a wire to the computer the terminal was controlling.
This copper pipeline to the processor is still basically how the terminal emulators function today. They just don’t require any more hardware than a monitor and keyboard. We consider ourselves fairly advanced Linux users, but the noob and expert alike will find nuggets and tidbits which are sure to switch on the lightbulb in your mind.
Retrotechtacular is a weekly column featuring hacks, technology, and kitsch from ages of yore. Help keep it fresh by sending in your ideas for future installments.
Modern operating systems may seem baroque in their complexity, but nearly every one of them – except for Windows, natch – are based on the idea of simplicity and modularity. This is the lesson that UNIX taught us, explained perfectly in a little film from Bell Labs in 1982 starring giants of computation, [Dennis Ritchie], [Ken Thompson], [Brian Kernighan], and others.
At the time this film was made, UNIX had been around for about 10 years. In that time, it had moved far from an OS cloistered in giant mainframes attached to teletypes to slightly smaller minicomputers wired up to video terminals. Yes, smallish computers like the Apple II and the VIC-20 were around by this time, but they were toys compared to the hulking racks inside Bell Labs.
The film explains the core concept of UNIX by demonstrating modularity with a great example by [Brian Kernighan]. He took a short passage from a paper he wrote and found spelling errors by piping his paper though different commands from the shell. First the words in the paper were separated line by line, made lowercase, and sorted alphabetically. All the unique words were extracted from this list, and compared to a dictionary. A spell checker in one line of code, brought to you by the power of UNIX.
We normally try to be descriptive with our titles. But when that statement pops out of the narration with notable excitement it made us chuckle. This installment of Retrotechtacular is a promotional video for the Blit. It’s a graphics-based hardware terminal for Unix systems. It’s biggest boast is the ability to run (and display on screen) several different programs at once — an activity called multiprogramming. But there is also the “digitizing mouse”. On board is a 68000 microcprocessor 256k of RAM (they call it a quarter meg), and connects via RS232. The screen is 800 by 1024; that’s right, it’s a portrait orientation.
Notable in this episode are some classic eyeglass frames, and rad synthesizer sounds for scene transitions. Whatever happened to videography technique that uses a dimwitted companion to ask that all-knowing narrator stupid questions?
Continue reading “Retrotechtacular: The Blit Has Given Me Access To The Power Of Multiprogramming!”
We figured it wouldn’t be long before someone figured out how to remove the ads from the ‘Special Offers’ versions of the Amazon Kindle hardware. There are two things that made this obvious to us, the huge flaw that lets code be easily run as root, and the MP3 tag forming that makes it possible to unlock the device.
[Pat Hartl] knows his way around a *nix shell, so once he gained SSH access to the device he started a search for the ad images that make up the special offers feature. He found them in a few different places, making backups of the files in an alternate location, then removing them with some simple commands. He even rolled the process into a one-click installer like the Jailbreak package. It makes us wonder if Amazon has a way to tell if your device is not longer pulling down content for these offers?
At risk of sounding preachy, Amazon does offer this hardware without ads for a one-time fee. Circumventing the unobtrusive ads may lead to higher hardware prices in the future, and [Pat] mentions that. He pulled off this hack to show the holes in Amazon’s security, and hitting them in the pocketbook is a powerful way to do it.
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Chances are you have already heard of the passing of [Dennis Ritchie]. We admit, we’re among the throngs who knew little of his life, but [Cade Metz] has posted an excellent remembrance of his life which we think is well worth reading.
[Dennis] passed on October 12th at the age of 70. This image shows him receiving the National Medal of Technology awarded to him by [Bill Clinton] in 1998. His legacy lives on in the work that earned him this award as the creator of the C programming language; a side project which he developed to help him achieve the creation of a new system kernel called UNIX. This work, of course, was the precursor that led to universal software packages like OSX, iOS, Linux, and even Windows (which at one point was itself written using the C language).
There has been some Internet fodder regarding media coverage of [Steve Jobs’] death and not of [Dennis’] passing. It’s harder for those lacking experience with programming to comprehend [Dennis’] contributions. We’re glad to have an opportunity to pass on the story of his life and to take a moment to appreciate his accomplishments.
A lot of people like fancy GUIs and nice graphics, but some of us just feel more at home in a command prompt. [nevdull] is one of those people. Instead of just using the Arduino dev tools that are available for download, he wanted the ability to shell into his Arduino, so he created AVR Shell. AVR Shell is a UNIX-like shell that allows you to “log in” to your Arduino/AVR and see what’s really going on; letting you read registers, scale the CPU speed, create/edit/delete variables, and even set up timers. The shell is even user-customizable! Those of you interested in Arduino shells might also check out bitlash, another open source CLI. Someone ought to hook this up to the Internet enabled Furby and get Flite compiled on there, letting us shell into a Furby from miles away to make it talk.
The G1 ‘execute every command you type‘ bug naturally spawned ‘rm -rf /’ jokes. rm is the Linux command for deleting files. The -r and -f flags will cause it to remove files recursively and ignore confirmation. Executed as root it will annihilate the entire filesystem. Won’t it? [Jon Hohle] decided to test exactly how destructive the command was to *nix systems. How functional would the system be afterwards? He tested it side by side with the Windows equivalent, both ‘format c:’ and ‘del /F /S /Q’. He wanted to see what protections were available and what would be left working. Linux ended up completely broken while Windows, thanks to file locking, actually shutdown cleanly… and never came back. Some OSes, like Solaris, refuse to run the command ‘rm -rf /’ to prevent accidents.