Clockwork Pi DevTerm Review: Hands-on with the Ultra-Compact TRS-80-Inspired Kit Computer

Built from a kit of parts, this open-hardware ode to the TRS-80 Model 100 boasts ultra-wide display, keyboard, trackball — and printer.

Gareth Halfacree
15 days agoHW101 / 3D Printing

While it may be difficult for younger readers to believe, there was a time before ultra-portable laptops and high-performance tablets. A time when to take your work on the road either meant a luggable that would put your back out or a relatively limited notepad-style device with a wide screen sat above a built-in keyboard.

The world may have moved on, but Clockwork Pi is confident there’s demand for the latter form factor still. The DevTerm, the modern reinterpretation of the Kyocera Kyotronic 85 design the company announced a year ago, is its attempt to prove that — and it’s a very bold attempt indeed.

Building on the success of its modular build-it-yourself GameShell games console the DevTerm takes the concept and runs with it, resulting in a device that feels both nostalgic and modern — and which takes up a surprisingly small amount of room on your desk.

The hardware

  • Price: $339 (for A-0604 as reviewed, models starting from $219)
  • CPU: Rockchip RK3399 (2× 1.8GHz Cortex-A72, 4× 1.4GHz Cortex-A53)
  • GPU: Arm Mali-T860 MP4
  • RAM: 4GB LPDDR3
  • Display: 6.8" IPS 1280×480 16:6 ultra-wide
  • Storage: MicroSD (16GB included)
  • Networking: Dual-band 802.11ac Wi-Fi, Bluetooth 5.0
  • Ports: Micro-HDMI, 3× USB 2.0, 3.5mm audio in/out, MIPI CSI (internal), micro-USB UART (internal)
  • Peripherals: 65 percent compact keyboard with game controls, three-button trackball, 58mm 200 DPI thermal printer with removable paper cassette
  • Dimensions: 209×159mm exc. paper cassette (around 8.23×6.26in)

The DevTerm is a family of products, really. Each model in the range shares a common shell, extension board, motherboard, and peripherals, but with a different system-on-module at its heart. The base model, RPI-CM3, is designed to accept a Raspberry Pi Compute Module 3+ Lite with 1GB of LPDDR2 RAM and a 1.2GHz quad-core Arm Cortex-A53 processor; the A-04 models take a custom SOM with 1GB or 2GB of LPDDR3 and a 1.8GHz quad-core Cortex-A53; the top-end A-06 models have a choice of 2GB or 4GB LPDDR3 and a six-core processor, which mixes two 1.8GHz Cortex-A72 and four 1.4GHz Cortex-A53 cores.

The model on review is the range-topping A-0604, which affects the benchmark results: The device is more powerful than the A-04 or RPI-CM3 models, boosting performance, but draws noticeably more power from the batteries — dropping runtime. The display, keyboard, trackball, ports, and that oh-so-anachronistic thermal printer, however, are identical between models.

As with the GameShell, the DevTerm arrives as a kit of parts. There’s no soldering, and only one part of the process — securing the SOM from moving using two Phillips-head screws — requires a tool. The process takes no more than an hour, though the printed manual supplied is a little vague on a couple of points — and fails to discuss the heatsink, bundled with the A-06 models to improve cooling, at all.

The hardware in general is, as is usual for Clockwork Pi products, cleverly designed and high-quality. There does, however, appear to be an issue with the display: The test unit skipped the first four rows of pixels, cutting down an already-low 480 vertical pixels to sub-VGA heights. Whether this is a hardware issue or something that could be corrected in firmware was not clear at the time of writing.

The keyboard is smaller than it looks, especially if you’re expecting something the size of an equivalent machine from the 1980s. Each key is a little over a quarter the size of the corresponding key on a traditional keyboard, making for a cramped feel. It’s possible to touch-type, just about, but it definitely takes some getting used to — as does the BlackBerry-style tiny trackball at the top, which suffers from slow movement across the ultra-wide display even at maximum acceleration and speed settings.

No review of the DevTerm could be complete without mentioning the printer, of course. While the Kyotronic 85-based TRS-80 Model 100 which served as inspiration for the DevTerm had no built-in printer, the Epson HX-20 that came out a year before had one to the lefthand side of the screen — though the DevTerm’s is located to the right.

A bundled plastic paper cassette with clever clip to keep things closed in transit accepts 58mm thermal rolls, commonly used in receipt printers, up to a 40mm diameter; printing is done in black-and-white at 200 DPI.

An open source CUPS driver is provided, but could use a little work: It insists on paginating, despite the use of a continuous paper roll, and setting the “page” length to the maximum permissible to avoid frequent gaps wastes nearly six inches at the top of each print out. Prints are small yet clear — though text works better than images unless you’re willing to pre-process them to black-and-white with ordered dithering, in which case they come out surprisingly well — but the process is slow.

For those eager to get their system up-and-running post-purchase, a warning: Unlike the GameShell, the DevTerm does not include any batteries in the bundle. Instead, you’ll need to provide them yourself: A matched pair of 18650 lithium-ion cells, preferably protected. Runtime will depend on the quality and capacity of the batteries you purchase: The test unit managed three hours and 49 minutes of video playback with a pair of 3,400mAh cells installed; charging them again from flat took two hours and 18 minutes.

The software

The DevTerm is provided with a 16GB micro-SD card onto which a custom Linux operating system has been written. It’s not wholly a Clockwork Pi creation: It is based on an Ubuntu 21.04 build from the Armbian project, which given said project’s dictatorial development style and propensity to release feature-breaking updates without adequate testing isn’t necessarily a good thing.

On the one hand, using Ubuntu Linux as a base is a great move: It provides strong compatibility with a wealth of software, from popular productivity tools to web browsers, development suites, and even games. On the other, it can lead to awkward moments where a desktop environmental clearly built with higher-resolution displays in mind sees you dragging dialog boxes around the place to see options and buttons, which have disappeared off the bottom of that 480-pixel-high ultra-wide panel.

Diving into the performance also reveals a surprise: The DevTerm arrives with a severely restricted processor. While the A-06 models are advertised with those two 1.8GHz Cortex-A72 and four 1.4GHz Cortex-A53 processor cores, the system boots with only the Cortex-A53 cores running — and locked to a maximum speed of 1GHz.

ClockWork Pi does, thankfully, provide a tool for “changing gears” from a list of six possible performance settings. At the minimum setting, only a single Cortex-A53 core is active and at the lowest speed possible; at the maximum, all six cores are enabled at their rated speeds. The same tool also changes the maximum clock speed of the GPU — and, as a simple shell script, can be easily edited to include your own preferred configurations.

At the top performance setting, the DevTerm responds as you’d expect an RK3399-based system to respond — at least, initially. The thin heatsink and small, but thankfully extremely quiet, blower fan can’t handle the RK3399 at its rated performance for long: In real-world use you may get a few minutes of sustained load before it begins to throttle, but in a thermal torture test the CPU speed began to nosedive after just three seconds.

The software, which to be fair is clearly marked as v0.1, is also somewhat buggy. Suspend-to-RAM is possible, yet waking up again isn’t: The DevTerm responds over a network connection but the on-board display remains stubbornly blank. Users have reported, though it was not reproducible on the review unit, instability and reboots under the maximum performance settings, too, and setting up the micro-HDMI as an external display needs a bit of fiddling - assuming that the side panel doesn’t prevent your micro-HDMI cable from making proper contact, which was the case for any cables on-hand during the review.

For the most part, the DevTerm is entirely usable, despite the issues above. Most software is just about able to handle a screen just 480 pixels tall, and for older packages designed with a 640x480 display in mind you can run two side-by-side at their native resolutions. It will be interesting to see if the retro-gaming community does anything with that functionality — displaying information about the game under emulation at one side while the game plays at the other, for example.

Conclusion

The DevTerm is too small to be entirely practical as a daily-driver portable. It’s too large, ironically, to replace a tablet or smartphone as an everyday carry computing device. It’s an anachronistic wonder in a world that had almost entirely moved on to clamshell-style laptops with, for the most part, near-identical designs.

But that’s what makes the DevTerm special. By all rights it shouldn’t exist, but it does. It certainly shouldn’t be in an all-plastic housing with 3D models available should you want to print replacement parts or an entirely new case, but it does. It definitely shouldn’t have a thermal printer built in, but there it is.

If you go into buying a DevTerm with the expectation that it’s a modern reincarnation of the TRS-80, based purely on photographs reproduced with no easy way to determine scale, you’ll be disappointed by a cramped design. If you accept it for what it is, though, it’s all-too easy to fall in love with what Clockwork Pi has created — warts and all.

There is also talk of new Core SOMs, which would act as drop-in upgrades for the DevTerm, with "FPGA+ARM, RISC-V, and even x86 architecture" offerings being proposed by Clockwork Pi. With the company still working hard to meet demand for the existing models, though, it could be a while before any such devices launch.

Pre-orders for the next batch of DevTerms are expected to open in the coming weeks on the Clockwork Pi web shop, where the entry-level DevTerm RPI-CM3 kit starts at $219.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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