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Cosmo Communicator Review: the dual boot pocket PC phone

By Adam Z. Lein August 12, 2020, 8:00 am

Around the turn of the century, smartphones came in many clever and innovative shapes and sizes. For about 10 years, we lost that innovation to rectangular touch screen slabs, but now some of that innovation is coming back. The Cosmo Communicator is a good example. It’s an Android smartphone with a real physical keyboard, a clam-shell hinge to open it up, and an external screen. It even allows you to partition the storage area and install full Linux for a dual boot experience.


The Cosmo Communicator is 171.4mm long, 79.3mm wide, and 17.3mm thick. It’s not a small device. The weight is 326g, so it’s not light either. It’s got a 4220mAh battery with fast charging, 5.99″ FHD 2160×1080 pixel main display, 1.91″ external OLED touch display, 24Mp external camera with LED flash, and 5Mp front-facing video call camera. It supports all of the GSM, CDMA, and 4G LTE radios and is also available in a Verizon version or Japan version for those different frequencies. You’ve got dual nano-SIM card slots and eSIM support as well. It comes with Android 9.0 installed, but now with recent updates, we can also install a special version of Debian Linux. Sailfish might work too.


For a processor, it uses a MediaTek Helio P70 and includes 6Gb of RAM and 128Gb of storage. Of course, there’s WiFi, Bluetooth 5.0, HD Stereo speakers, noise suppression microphones, GPS, NFC, fingerprint scanner, and a 3.5mm audio jack. There are also actually two USB-C ports! One on each side. The left side is best for charging, by the way.

Even the box has a clamshell flip up design.

Hardware and Design

Opening the clamshell device is a little difficult. It takes two hands to pry it open, but once you do, there’s a gorgeous keyboard inside. The keys look full-sized, but they’re obviously smaller to fit the small form factor. They have excellent key travel. Putting two hands on the keyboard and trying to touch-type isn’t so great since it’s such a different size. Plus there are not tactile raised bumps on the “J” and “F” keys for finding your place by touch. That’s something that I wish the designers had included.

Really the keyboard works best as a thumb keyboard where you hold the device in two hands and type with your thumbs like you would with an old blackberry. This method works well except the Shift key is not sticky, so you have to use the Shift keys and modifiers on both sides. Instead of just hitting the Shift key once and then typing the key you want to be uppercase, you have to hold it down. That means if the key you want to shift is on the left side of the keyboard, you have to use your right hand to hold down the Shift key on the right side of the keyboard. It takes some getting used to.

On the outside, there are a lot of controls so that you can use some phone aspects and see notifications without having to open the device. We’ll talk about this in more detail later on. There’s also a fingerprint scanner where those two blue LEDs are and that area is also a rocker switch that works for interacting with the external screen as well as for volume control. You can also see the 24MP external camera at the top. The grey side pieces are metal while the blacktop pieces are rubber. It’s a very unique and distinctive design!

The back of the device is all smooth metal with hard rubber ends. It feels very sturdy.

The Planet Computer logo on the back looks great.

The hardware branding is not too obtrusive and it’s nice to show what this device actually is. A lot of phones don’t label themselves very well anymore.

There’s even some nice branding on the edge where the screen and keyboard open.

The right edge has the silver power button. It’s flush with the device, so you won’t press it accidentally. There’s also a USB-C port here along with some microphone and speaker grill holes.

The left edge of the Cosmo Communicator also has another USB-C port along with the 3.5mm headset jack, some more speaker/microphone holes, as well as a slot for the NanoSIM card and MicroSD card tray. The tray can accommodate two NanoSIM cards or one NanoSIM and a MicroSD card.

The hinge has an interesting mechanism to it where an “L” shaped metal part extrudes from the edge to give you a raised keyboard kind of set up when using it on a desk. This makes for an opening that goes through the inside of the hinge, so be careful not to get any dirt in there. The rubber part of this hinge looks a bit damaged as well. Not sure how that happened.

I decided to compare the Cosmo Communicator to some of the old slide-out & tilt keyboard smartphones from the ’00s. The Cosmo Communicator is huge compared to the HTC Touch Pro 2 (center) and HTC Kaiser (left).

KDE Plasma Debian Linux

Recent updates in the firmware on the Cosmo Communicator have enabled users to partition the storage and install Debian Linux with the KDE Plasma desktop environment for dual booting the device between Android 9 and Linux. This is an awesome new feature for power users and tech enthusiasts. So of course, I wanted to do this right away.

By the way, this modified version of Debian Linux can be found on Github along with some of the other included programs if you’d like to take a look at the source code.

The Cosmo Communicator does not ship with Linux support available right away. In fact, the firmware to support this was only recently made available as part of the online updates. You will have to partition the storage area using the boot firmware, create a MicroSD card with the custom Linux installer downloaded, boot to the MicroSD, and then install from there. You can find the full instructions and the Linux installer downloader on the Planet Computers Linux for Cosmo Wiki page. Partitioning will lose everything on the Android side, so it’s best to do this before you really start using the Android side.

After receiving this review unit, I installed version 1 of Linux for Cosmo from February of 2020 and a lot of things didn’t work right away with that one. There was no phone calling, SMS, or LTE data support. Only WiFi networking really and even that didn’t save my password. Version 2 was released later on in July of 2020, and that brought a phone app, SMS messaging app, and LTE data connection support, but getting LTE data connections to work even in version 2 requires a lot of work as you can see here.

Once you get Linux running, you’ll need to enter the username and password, which are both “cosmo”. There is no onboarding interface that lets you create your own username & password. Also, this is the KDE Plasma desktop environment which isn’t very well designed for keyboard interaction (there are no visible keyboard access keys)… nor is it very well designed for touch screens (interactive elements are very small). By default, the touch screen acts as a left click poke. Meaning that you point and touch something and that acts as a left click on that item. Scrollbars are very thin in the default theme as well, so those are impossible to use. I was able to enlarge the scrollbars and many buttons by customizing the system theme.

The KDE Plasma interface is so poorly suited for a device like this, you might be better off just typing terminal commands for everything. Still, I was able to install xserver-xorg-input-mtrack, which makes the touchscreen act like a trackpad that moves the pointer around on the screen. Instructions can be found here. If you’ve used Remote Desktop apps on phones before, the effect is very similar. Swiping the touch screen makes the arrow move around, tapping causes a left click at the pointer’s location. This modification helps a lot. Alternatively, you can always plug an actual hardware mouse into one of the USB-C ports on the sides.

I was able to get the Graphical Image Manipulation Program installed, but its interface was not scaling well at all. The menus weren’t even accessible. So there are still some problems here.

Darktable works pretty nicely, but again it’s hard to work with on such a small screen. Still, it was able to load photos from a USB SD card adapter no problem… just like a real computer.

Of course, the venerable Libre Office works here as well, but again the user interface might be a struggle to use without a mouse on this small screen.

As of July 2020, there are now functioning SMS and phone calling programs in the Gemian Debian Linux build! They don’t appear with updates from the version 1 build, so I had to re-install Linux from the version 2 image download.

Incoming calls work as well and even include canned SMS replies. While the ringing works even if the phone is asleep with the screen off, nothing is displayed on the screen or the external screen… AND you have to enter your password to unlock Linux before you can see the answer dialogue. It’s certainly not perfect at the moment.

As mentioned, the external screen doesn’t work when booted into Linux and neither does the camera… or at least there is no functional camera software included yet and the web browser cannot recognize the existence of cameras for things like WebRTC video calls.

Android Software

If Linux is too much of a challenge for you, of course, you can always go back to the good old Android 9 partition with a reboot. Or if you want to hack Android a bit, you can also root the Android partition in order to do whatever you want there.

The Cosmo Communicator’s default Android home screen always switches to landscape mode. You’ve got the usual back, home, tasks (triangle, circle, square) buttons on the right instead of the bottom, and there are application icons all over. There is an application drawer for showing all of the other applications, but you can’t see it. There is no button to activate the application drawer. You have to learn the secret swipe up gesture on the home screen to find it.

Planet Computers has included some extra software to make Android a little better for keyboard devices. One is the “App Bar” that appears at the bottom. It’s kind of like a dock in MacOS or the taskbar in Windows whereas you can pin whatever programs you want to the app bar and rearrange their sequence. Then you can use the Planet Computers logo button (Alt) on the keyboard to show the app bar and then use the arrow keys to select the app you want to launch. This makes the keyboard usability of Android much better.

Even though the very first Android smartphones (Check out my review of the Android G1 from 2008), were actually designed for landscape/portrait switching and slide-out keyboards with decent keyboard navigation support. Today’s version of Android certainly is not.

Planet Computers also includes some other useful programs. Above is “Airmail” which is a decent email program based on the K-9 open-source Android email app. It’s got better information density than the default Gmail app and works well with the keyboard.

The Agenda app is another one that Planet Computers added. It’s a calendar program that syncs with the regular Android calendar libraries, but you can also sync it directly with a PC using a USB cable. That’s how things used to be before wireless internet was so prevalent and it has its advantages such as: not uploading your data to someone else’s computer in the cloud.

There’s also a basic Notes app. It doesn’t seem to sync with anything, but you can back up the notes to a separate file. It lends itself nicely to the landscape layout, but personally I’d rather use Microsoft OneNote.

There are a lot of LED lights on the outside of the Cosmo Communicator, and there’s a utility for customizing them here.

We’ve actually got a database program in the Cosmo Communicator too! You can import data from CSV files into tables and also export data to SQL, CSV, or TXT. It doesn’t connect directly to any online database servers though, so this is mainly for offline uses.

There’s also an app that makes it easy to specify which voice assistant you want to use with the keyboard shortcuts.

Planet Computers also includes a special file manager separate from Google’s Files app.

External Screen

Since this is a clamshell device that closes against its main screen, you can’t really see much when the phone is closed. Luckily there’s a small external screen on the outside. This will show you radio status, the time, and date normally, and it will also show icons that represent notifications that are waiting within Android.

You can open the notifications to get a little more information as well as some actionable options. Most of the actionable options will tell you to open the device in order to continue, but it will launch whatever app you’re trying to interact with so that it’s a little less disconnected.

There is also a grid of mystery meat icons that you can access with the buttons in the fingerprint scanner. These give you quick access to certain functions like phone calling, photos, video recording, flashlight, and music playback. Since this is also a touch screen, you can tap the circle icon you want to activate it. Unfortunately, this makes accidentally changing things while the phone is in your pocket very easily. I’ve accidentally switched to airplane mode and turned off all of the radios for the phone while it was in my pocket.

One awesome feature of the external screen is that you can use it to take photos with the external camera. Unfortunately, the viewfinder display here is extremely laggy. It’s often behind real-life by a couple seconds. So you really have to hold still to frame the selfie photo. Then the camera shutter button is often unresponsive as well, so you may have to hold still and also press the button a few times before it takes a photo.

There are a good number of settings in the external screen interface as well. You can change its orientation, brightness, notification text options, etc. As mentioned before, you can also control which radios are on. Here you see we’re using the “CODI” external display software version

Just so you know, getting the cover display software to update can be an absolute nightmare. It took me maybe 1.5 weeks of repeatedly pressing the “upgrade now” button, waiting for 20 minutes, seeing it fail, and trying again. There’s a “manual” upgrade option where you can download 2 files from Planet Computers and try to install those through the utility. If you navigate to them through the file browser’s “recent” list, then the whole thing will just crash. You have to go through the file browser’s main storage listing. This way it won’t crash, but it will still fail with an error. You also have to disable the cover display in the Android action center, as well as go into airplane mode to disable all radios. You also have to try to install the smaller update file first before the larger one it seems. Even then, it may not work, and the documentation is pretty thin. You’ll see lots of complaints about this on the Open Embedded Software Foundation website.


The external 24Mp camera sounds like it would be really good. If we were talking about a 24Mp camera on a Nokia Lumia phone from 7 years ago, then yes, it would be something really fantastic. Unfortunately, that’s not the case here. The image quality is disappointing. The camera software is disappointing as well. It has very very few controls. You can take a picture, take a video, turn on the flash, and turn on HDR mode. That’s it.

Installing Open Camera helps to give you a lot more control, but Android’s Camera API2 doesn’t get access to the camera’s RAW data, so we can’t really do further edits or customizations.

Above is a 100% crop of a JPG from the 24Mp camera. While it technically has 24 Megapixels, there is not much detail here at all. Everything is smeared and smudged. Below are a few more camera samples.


The 4,220mAh battery seems like a large number that should get you through a weekend, but in practice, it really might only last a day. Of course, all of this depends on what you’re doing with the device. Do you have the keyboard backlight on, is the external screen always on, what kind of programs are you running, are you trying to render animations in Blender on Debian? In general, I would expect the battery to last most of a single working day.

Pricing & Availability

You can order the Cosmo Communicator directly from the Planet Computers Store. There are 28 versions available with different language keyboards. It’s costs £665.83 ($871.64 USD) and not all language keyboard options are available at the moment. Some are still pre-order options. There is also a special version for Verizon radio bands in the U.S.A.

Pros & Cons


  • Big keyboard works great for typing
  • Dual boot to Android 9 or KDE Plasma Debian Linux with other operating systems coming soon
  • Desktop Linux gives you a lot more customization, computing power, and flexibility than Android
  • External screen gives you access to basic functions and notifications without opening the device
  • Two USB-C ports
  • 3.5mm headset jack
  • Extremely unique design


  • Very big and heavy
  • Includes Android 9 instead of 10
  • No wireless charging
  • Camera hardware doesn’t support RAW output via Android’s Camera API 2
  • 24Mp camera has very poor image quality
  • No water resistance
  • Difficult to use in portrait mode with Android apps that don’t rotate
  • Touch screen can be very difficult to use in KDE Plasma on Linux


The Cosmo Communicator certainly is not for the faint of heart. This is clearly a power-user device as even updating the software can be a massive undertaking. You’re going to need some courage and technical expertise to buy this phone. The big appeal for me is the fact that it can run full Linux outside of Android. The Linux side is still a work in progress, so the initial user experience isn’t very good, but improvements have appeared even while I was writing this review. Having Debian Linux on your phone means you have way more control than you would in Android or iOS. Plugging a mouse in and using the phone as a little laptop is really pretty awesome. The camera is terrible though, so I wouldn’t buy this if you like to take photos a lot while out and about. I would highly recommend this phone if you’re a programmer or white-hat hacker though, as the Cosmo Communicator gives you a lot more flexibility than you would have on a normal rectangular slab touch screen phone. You’ve got Debian Linux, unlocked root-able Android, Team Win Recovery Project support, and maybe someday, Jolla Sailfish.

15-20 years ago, many of us dreamed of having a full laptop computer that could fit in a pocket and still make & receive phone calls, browse the web and get email over wireless internet. Microsoft’s Windows CE/Mobile/Phone came closest to that dream… until now. Having full desktop Linux on a pocket-friendly handheld computer that still makes phone calls and has wireless internet is a pretty excellent dream come true.


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