Towards using a smartphone as a desktop computer

A smartphone connected to a screen and used as a desktop computer with a Bluetooth keyboard.

Hardware requirements

Bluetooth keyboard

Practically all smartphones support a Bluetooth keyboard. There are inexpansive foldable keyboards, hardly larger than the smartphone itself when folded. However, there often seems to be glitches with the character sets, especially if one uses a national character set. A useful app which can help solve such problems for Nadroid is the Extended Keyboard Helper.

HDMI Alt Mode adapter

The fundamental hardware requirement on the smartphone is that it should support HDMI Alternative (or Alt) Mode. This allows the smartphone to connect a USB-C socket (or a Lightning socket for iPhones) via a simple adapter to the HDMI socket of a large screen or TV. Although wireless connection is technically possible, it is usually too slow and requires that both devices are connected to the same wireless network.

Many smartphones recently manufactured by Samsung, OnePlus, Huawei, Motorola, Sony, LG, and Nokia seem to support HDMI Alt mode. Currently, it seems that Xiaomi, Realme,Asus, and Google Pixel do not support it, but they can use a DisplayLink converter instead.

With a USB-C-to-HDMI adapter, the desktop screen/TV will be able to mirror the smartphone screen more or less Plug & Play.

Bluetooth keyboard with carrying pouch and USB-C-to-HDMI adapter.

Pointing devices

Some smartphones can be used as touchpads when connected to screens. An alternative is to use a Bluetooth keyboard with a trackball or a touchpad. There are also more elaborate USB-C-to-HDMI adapters having an extra USB socket for attaching a USB mouse.

Software requirements

Window handler

Using the USB-C-to-HDMI adapter, the screen can mirror the smartphone’s screen, but this is not too exciting. The same effect can be had by a Fresnel lens that can be bought very inexpensively from AliExpress or Wish.

It is important that the smartphone has a Window handler which utilizes the lartge screen and allows moving and resizing multiple windows on the screen. To the best of my knowledge, so far (February 2021), only Samsung and Huawei offer this functionality by the “DeX” option, and “EMUI Desktop view”, respectively.

Promising for the future, however, is that there is unofficial support for a desktop mode built into Android 10. We can hope that such functionality becomes officially supported from Android 11!

Desktop versions of apps

Apps that have been developed for smartphones are not necessarily optimal for desktop screens. A shortcut to obtaining advanced “apps” (programs) to use on the smartphone is to install package such as termux, which complements the Android OS to make the smartphone much more similar to a Linux computer. This allows very easy installataion of a full-fledged Emacs, C compiler, etc.

Unfortunately, there are two serious problems here: First, installing such powerful software opens up a large security hole on the smartphone, a risk that can be confirmed by a quick search on internet. Second, access to the file system, which is crucially important for termux and similar programs, will reportedly be severly restrained in future versions of Android, presumably due to the security issues. At the time of this writing, it is unclear what the future will be like.

Conclusions

A smartphone is a device that excells in communication. A desktop computer excells in computation. From a user’s point of view, it would be very nice to be able to combine these two into a single device. However, it seems that this also makes the device an attractive target for and vulnerable to cracking. It will certainly be interesting to see if this problem can be solved in the future.