Tedium - The Execution of All Things 💾

Dennis Ritchie and Ken Thompson running UNIX on a PDP-11, utilizing teletype-style terminals, in case you’re wondering how old we’re talking here. (Kenneth Martin/Flickr)

1. a.out File Format

Era: 1960s-1990s

Operating Systems: anything related to UNIX

Most common file extension: a.out

This is one of those executables that has a famous name attached to it. Ken Thompson, one of the primary developers of UNIX, built this executable format, which stands for “assembler output,” was one of the first types of executable that was supported by modern computing platforms.

Thompson developed the format in 1968 for the PDP-7 minicomputer, and it gained fame a few years later after Thompson and his Bell Labs colleagues developed UNIX with the help of said executable.

Later versions of UNIX moved to other executable formats, most notably the Executable and Linkable Format (ELF) format leveraged by most UNIX-based systems today, as well as the Mach-O format used natively for MacOS executables.

While primitive by today’s standards, a.out had a long life—it was supported by Linux, for example, until version 5.18 of the kernel, which came out only back in May.

(Super Snapper/Unsplash)

4. Amiga Hunk format

Era: 1980s-1990s

Operating systems: Amiga

Most common file extension: None

If you ran an executable application on an Amiga, this was your format. Built for running applications on the Motorola 68k processors, the format was initially managed by Commodore, and applications could be built from an array of distinct hunks that were joined together within program units.

A noteworthy feature of the format compared to most of the others on this list was that it was not dependent on file extension, because Amiga uses another detection method, reliant on the file header, to understand whether a file is executable or not, called a “magic cookie”—essentially, it looks for a specific set of bytes to know whether the file is executable.

Modern Amiga-style operating systems such as AROS or MorphOS, while still able to run Hunk files, tend to support the more-common ELF-style executable format, which is used in UNIX-style operating systems like Linux and FreeBSD.

When you’re done reading this article, play this video on your computer in full screen.

7. Windows Screensaver File Format

Era: 1990s-(very faintly in the) present

Operating Systems: Windows

Most common file extension: .SCR

In the era of cathode ray tubes, having a solid screensaver was important, taking on a similar role in many offices to, say, putting a picture on your smartphone. It was a cute way of showing personality, especially if you were a fan of flying toasters or the Energizer Bunny (the latter being the subject of one of the best-ever Medium posts).

At least in Windows, screensaver files are treated as executables, meaning that when you pull up a screensaver on the Internet Archive, it’s actually an executable file. While that means you can run a screensaver at will, it also meant that it was at risk of being exploited, whether by Trojan horses or by malformed screensaver files.

While Windows technically supports this feature today—in fact, with light modifications, you can run a Windows 3.1-era screensavers in modern versions of Windows—screensavers have become significantly less common in an era of LCD screens, which face fewer burn-in risks, and if you try to load one on your laptop, Windows dialog boxes actually discourage you from using them because of the fact that they waste energy you could otherwise use.

TweetDeck grew quickly on the back of Adobe AIR, though once Twitter acquired it, they immediately moved way from the programming framework. (via WebUpd8)

10. Adobe AIR Installation Package

Era: 2000s-2010s

Operating Systems: Windows, MacOS, Linux, iOS, Android, BlackBerry

Most common file extension: .AIR

This executable format was in many ways Adobe’s embrace of the fact that Flash had evolved into a native programming environment of its own—think of it as Adobe’s attempt to turn Flash into something like Java.

Its 2008 launch was well-timed, as it allowed the company to take advantage of the burgeoning mobile revolution, adding support for websites with standalone applications that could be extended across platforms to mobile apps. Fittingly, two very famous apps were created with the AIR technology—Angry Birds, one of the earliest viral mobile games, and TweetDeck, an alternative Twitter client for power users. It was a great way to get around Steve Jobs’ thoughts on Flash.

Technically this is not truly dead, but in a maintenance mode. In 2019, Adobe handed off the development reins of this software to the Samsung subsidiary Harman International, which is maintaining it in part because it is used for a number of enterprise use cases. Notably, Harman revived a key use case that Adobe killed—Android support.

This decision to maintain it only for enterprise use does have some dissenters—a Change.org petition has called on Adobe to open-source the technology, though it only has 16 signatures. Maybe you might feel compelled to make it 17.