PlanetWatt unveiled wattOS R10 in September 2016, which is based on Ubuntu 16.04.1 LTS for long-term support and stability [1]. Since a tentative beta was released in July 2013 [2], releases have been on roughly an annual basis.

Despite the emphasis on energy-efficiency, this isn't apparent from the boot menu or the rather leafy desktop, which is at once very easy on the eye, but contains minimal clutter. By default only three apps are displayed. Besides the habitual trash can, the default desktop contains shortcuts to the Firefox v48.0 web browser and the Lollypop v0.9.112 music player (Figure 1).

Figure 1: The default wattOS desktop using LXDE. Desktop shortcuts have been placed for more common apps, such as Firefox and Lollypop.

WattOS' spartan LXDE desktop environment is coupled with the lightweight i3 window manager. PlanetWatt, the project developers' website, claims that any system that has a processor released in the last 10 years is compatible with the operating system (OS). WattOS requires 192-256MB of RAM for installation, but the website claims that less than 128MB are required once the install is complete. When testing in VirtualBox, I found that 256MB of RAM and 35MB of video memory was more than enough to keep wattOS ticking over nicely.

Try Before You Buy

If the lure of a lightweight distro appeals, 32- and 64-bit versions of wattOS are available from the developer's site via BitTorrent or direct download [3]. Both versions can fit fairly comfortably on a single CD-ROM.

Like most Ubuntu-based distros, the CD-ROM can be used in live mode for testing purposes, subject to the usual proviso that any changes you make or files you save will be lost on reboot. The installer is identical to Ubuntu's. For the security conscious, full disk encryption is supported, as is home folder encryption. WattOS comes with powertop preinstalled, so it can be installed alongside other OSs, such as Microsoft Windows.

The installer also contains the only bug I could find in wattOS: When entering your name, the username field remains as guest rather than suggesting your forename automatically. This can be updated manually, but it could be a nuisance for less experienced users who may inadvertently hitch themselves with an unwanted username.

Watt Apps

Once installation is complete, take time to enjoy the crisp greenery of the desktop background and then click on the Applications menu to explore the default programs.

Time and care have been put into providing a minimal set of useful applications that will not overburden the system. WattOS R10 has switched to using the Lollypop to give users access to a wide variety of music stations, saving the trouble of downloading music.

KeePassX 2.0.2 has been included for password management. Firefox is accompanied by Filezilla 3.15.0.2, as well as the Transmission BitTorrent client.

The most recent iteration of wattOS also now includes gThumb 3.4.3 as the default image editor (Figure 2).

Figure 2: Use gThumb to edit your favorite cat pictures. Launch from Applications > Graphics.

WattOS' focus on efficiency makes it an attractive prospect for laptop users. To this end, the System Tools section now contains Laptop Mode Configuration . While not as beautifully laid out as the rest of the system, this utility allows you to enable or disable a number of energy saving features. Some of these are already activated, such as auto-hibernate and Intel's Powersave mode. Others such as Bluetooth are disabled by default until needed.

Click Preferences > Firewall Configuration to open Gufw, the handy graphical front end to Uncomplicated Firewall (UFW). Aside from saving the trouble of entering firewall rules via the command line, Gufw has many preconfigured settings to allow connections by popular programs, saving you the trouble of remembering individual port numbers.

Under the hood, WattOS R10 has added Dynamic Kernel Module Support (DKMS) and legacy broadcom support, meaning more wireless cards and other hardware should be supported out of the box. Purists will be pleased to know R10 uses version 4.4.0-38 of the Linux kernel [4].

Watt Omissions

Having discussed the careful selection of apps in wattOS R10, it's wise to focus also on those that have been removed since the last version.

R10 uses the ultra-zippy i3 as the default window manager as opposed to Openbox, which came bundled with wattOS R9. Samba appears to have been removed. The Midori web browser and Audacious music player have been replaced with Firefox and Lollypop respectively.

Lollypop will happily play music files such as MP3s out of the box, but other media files such as MP4 video have no associated app. The installer has the option to download some third-party codecs during setup, although this may cause issues (see below).

Applications > Office contains only the Evince document viewer, which can display PDFs. Use LXTerminal or the preinstalled Synaptic package manager to install additional software, such as VLC media player and LibreOffice.

On the plus side, the size of the wattOS R10 ISO is now well below 700MB allowing it to be easily burned onto a CD-ROM, whereas the previous version was 711MB, which required users to employ overburn or use a USB stick.

Microwatt

How do you improve on an OS that has already been stripped down to its bare bones for sheer efficiency? The answer naturally is to create an even more stripped down version of that same OS.

PlanetWatt released Microwatt R10 on September 23, 2016, shortly after the release of WattOS R10 itself. Microwatt is also based on Ubuntu 16.04 LTS, and its core system is based on version 4.4.0-38 of the Linux kernel.

The stable version (4.11) of the i3 tiling window manager has also been preinstalled to offer a lighter memory footprint than wattOS' LXDE version. The PlanetWatt team claim this results in an improvement of 20-40% on average [4].

Microwatt comes with virtually no preinstalled apps. Surf v0.7 is available for basic web browsing. The minimalistic MuPDF version 1.7a-1 is also preloaded for viewing PDF documents. Aside from the PCManFM file manager (Figure 3), there are few other utilities.

Figure 3: PCManFM as it appears in Microwatt R10. i3 displays system information at the bottom of the screen but windows cannot be minimized here.

Fortunately one of the few utilities that does come preloaded is Synaptic, allowing you to install extra applications. The desktop also lists hot keys to launch the terminal, file manager, and web browser respectively by using the Windows key and a combination of letters. Mac users can rest assured that the Command key works just as well.

As there is no desktop environment per se, navigating windows can be tricky. As such, it's best to use the terminal app to launch and kill processes as you need them. Alternatively you can install a new desktop environment.

It's no surprise then that PlanetWatt refer to Microwatt as a "do what you want" release. The OS allows you to browse through the various software available before deciding on your program of choice. Needless to say, Microwatt also incorporates the power management utilities of wattOS to optimize it for laptops. This is helped in no small part by the battery, RAM, swap, and CPU usage stats, which are permanently displayed at the bottom of the screen.

Just like wattOS, the ISO for Microwatt R10 can be downloaded directly or via BitTorrent, but it is a mere 627MB meaning it will fit onto all CD-ROMs.

PlanetWatt

The wattOS developers' website, PlanetWatt, seems to echo the bare-bones feel of both wattOS and Microwatt. In the first instance, entering http://www.planetwatt.com into your browser will result in an admonition to go to the "new" website, which appends /new to the original URL.

PlanetWatt does contain links to a Wiki for both wattOS R10 and Microwatt R10, but at the time of writing, these were just landing pages. Fortunately the website has very active forums including threads dedicated to announcing the release of R10 for each OS [5], as well as a Rocket.Chat chat room with a dedicated channel for the latest version [6].

The website claims that confused users can message wattOS' main developer Biff Baxter. Whether or not this is his real name or if he is paying homage to Jeff Daniels' character in the 1987 comedy Radio Days , Biff plays an active role in both the forum and chat rooms and responds promptly to questions about usage and release dates of new versions of wattOS and Microwatt.

Watt a Mess

Users who try to test drive wattOS in VirtualBox may find that they see mysterious colors on screen and their device fails to load at all. You may be able to fix this by increasing the available video memory to the virtual machine. Failing this, go to Settings > System and check the box marked Enable EFI (Special OSs only) . These settings will only apply to the wattOS virtual machine, so do not worry about this interfering with the operation of others.

Similarly Microwatt can experience kernel panic in a virtual machine if started with too little video memory. I found that allocating at least 24MB video memory in the Display tab and enabling 3D acceleration allowed Microwatt to load normally.

Although wattOS can technically install software capable of playing high-definition videos or processing large amounts of data, it will still be constrained by the hardware specs of your system, so do not expect to turn a 10-year-old PC into a high-end gaming server simply because it has an efficient OS installed.

Users in need of technical support can head to the PlanetWatt forums. According to the official thread announcing the release of R10, current known issues include the installer crashing when choosing to download third-party codecs to play media, as well as both encrypting the system and home folder. In the meantime, the forum admins suggest choosing only one type of encryption and downloading the necessary third-party codecs post-install.

Watt am I?

Out of the box, there is very little that wattOS or its smaller Microwatt companion can do. As a user, it is down to you to decide which applications to add, which will commence on startup, and how your power-saver settings will be managed. Advanced power users may be delighted about this given that they can finally customize their Linux OS according to their whims.

Newcomers to Linux may find this distribution is not to their taste unless they are willing to become very well acquainted with the Synaptic package manager and/or the command line. In particular, navigating the i3 window manager in Microwatt can be tricky for those who are not Linux veterans. Certain applications do not play well together, so it may take some time before you can shape a system entirely to your taste.

Remember that both wattOS and MicroWatt support Ubuntu's "live" mode, to allow you to test run your configuration of choice. If you do try to install extra programs, however, bear in mind the CD-ROM will load into your RAM memory, so you'll be limited by the available space there. Performance will also not be as fast as when the OS is installed to your hard drive.

Overall, WattOS is by no means the only lightweight Ubuntu-based distro out there. However, the small ISOs, fast loading times, and high degree of customization make it a strong contender. The thought of dusting off the old PC in the attic and giving it a new lease on life is also very exciting. PlanetWatt maintains that wattOS will run on machines up to 10 years old. Should you decided to experiment with the OS on an old and/or low-spec PC, make sure to post in the wattOS forums with details of your configuration.