Pomera DM250 Tinkering

posted on march 14th, 2025
with tags hardware and openbsd
last updated on july 9th, 2025

The KING JIM Pomera DM250 "digital typewriter" is a small Linux-powered ARM computer that boots up into a custom word processor application. I've been tinkering with it to try to get OpenBSD booted on it. I'd normally wait until the end and write up a proper article explaining everything, but this process is taking a lot longer than I expected so I figured I'd document it all as I go.

[画像:Pomera DM250 ripped apart]

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Live Streaming a Macintosh Plus (or Any Compact Mac)

posted on february 21st, 2022
with tags mac, openbsd, and retrocomputing
last updated on march 26th, 2022

Since recording a handful of C Programming on System 6 videos, I've occasionally wanted to live-stream the more casual daily programming being done on my Macintosh Plus. After getting all of the pieces together, I now have a working self-hosted broadcasting setup.

If I happen to be programming on my Mac right now, you can watch here at my website.

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Debugging an ioctl Problem on OpenBSD

posted on february 16th, 2022
with tags debugging and openbsd

I was trying to use a V4L2 Ruby module on my OpenBSD laptop but ran into a problem where sending the V4L2 ioctls from this module would fail, while other V4L2 programs on OpenBSD worked fine.

Since I got a few questions recently about kernel development and debugging, I thought I'd write up how I finally tracked it down and fixed it. (Spoiler: it was not an OpenBSD problem.)

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OpenBSD on the Huawei MateBook X (2020)

posted on august 20th, 2021
with tags hardware, laptops, and openbsd
last updated on august 24th, 2021
part of OpenBSD on Laptops series

My old 2017 Huawei MateBook X has been my most reliable laptop and continued to be my daily-use workstation despite trying half a dozen others (and a desktop or two) in the past four years. Every time I'd try a new laptop, certain components wouldn't work properly, or the keyboard would feel strange, or the screen quality would be poor, or a constantly-running fan or some coil-whine noise would drive me nuts. And every time, I'd return to my trusty MateBook X and everything would just work silently.

I finally have a newer model of the MateBook X and I'm happy to say it lives up to its predecessor and has replaced my 2017 model.

[画像:huawei matebooks x]

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Bluetooth Audio on OpenBSD with the Creative BT-W3

posted on november 18th, 2020
with tags openbsd
last updated on march 22nd, 2021

Fifteen years ago, NetBSD's Bluetooth audio stack was imported into OpenBSD. From what I remember using it back then, it worked sufficiently well but its configuration was cumbersome. It supported Bluetooth HID keyboards and mice, audio, and serial devices. Six years ago, however, it was tedu'd due to conflicts with how it integrated into our kernel.

While we still have no Bluetooth support today, it is possible to play audio on Bluetooth headphones using a small hardware dongle.

[画像:creative bt-w3 plugged into laptop on desk]

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Video: C Programming on System 6 - Adding a GUI to diff(1)

posted on november 4th, 2020
with tags mac, openbsd, retrocomputing, and video
part of C Programming on System 6 series

In the previous episode I quickly ported OpenBSD's diff(1) but there wasn't any interface to select files or scroll through the output. I've since added a proper GUI with the ability to select files or folders, and in this episode I walk through the GUI and filesystem code and then add a proper Edit menu. I also make a formal release of the code and binary available for download.

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Video: C Programming on System 6 - Porting OpenBSD's diff(1)

posted on october 28th, 2020
with tags mac, openbsd, retrocomputing, and video
part of C Programming on System 6 series

I've wanted a simple revision control system on my Mac since starting development of my IMAP client. Porting a large system like Git or even CVS would be overkill (and very slow), but maybe something small like OpenBSD's RCS implementation would suffice. For now, just having a diff utility would be helpful so in this video I port the guts of OpenBSD's diff(1) and show it generating a unified diff between revisions of a C file.

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OpenBSD on the Microsoft Surface Go 2

posted on may 15th, 2020
with tags laptops and openbsd
last updated on july 31st, 2020
part of OpenBSD on Laptops series

I used OpenBSD on the original Surface Go back in 2018 and many things worked with the big exception of the internal Atheros WiFi. This meant I had to keep it tethered to a USB-C dock for Ethernet or use a small USB-A WiFi dongle plugged into a less-than-small USB-A-to-USB-C adapter.

Microsoft has switched to Intel WiFi chips on their recent Surface devices, making the Surface Go 2 slightly more compatible with OpenBSD.

[画像:surface go on desk with keyboard attached]

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Arduino Development on OpenBSD

posted on december 17th, 2019
with tags arduino, hardware, and openbsd

Back in 2017, I bought an Arduboy, a fun little Arduino development system which integrates an ATmega32U4 8-bit CPU, 32 KB of flash storage, 2 KB of RAM, a 128x64 pixel OLED display, some buttons, a speaker, and a battery in a Gameboy-like package.

OpenBSD had an old Arduino package available without the Arduino IDE, and it instead included a custom Makefile for end-users to build off of for compiling projects. But it was all pretty old and crufty and kind of sucked the fun out of tinkering with a new piece of hardware.

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