Author: Martin

Back in 2013 I finally managed to get hold of a Busch 2090, a historical microcomputer learning kit I always wanted as a teenager but couldn’t afford. Apart from its historical value to me it is still a great tool to learn and better understand how computers work. At the time, Busch also sold a separate tape interface board with which one could load and store programs to ordinary music cassettes which made experimenting with larger programs a lot easier. Unfortunately the Busch 2090 I bought didn’t have one and it is extremely rare to find one on eBay. While I didn’t particularly mind so far, I’m playing with the thought of participating at the VCFB 2017 in Berlin later this year where it would be great to have the ability to quickly load and demonstrate different programs. The more I thought about it the more I got interested and decided that instead of trying to buy the historical hardware I would find out if I could build a hardware emulator with a Raspberry Pi. This blog entry is part 1 of the story around that project. If you are interested in historical computing or reverse engineering an interface to build an emulator hardware and software for it, read on.

Continue reading Emulating a Busch 2090 Tape Interface – Part 1

When I was in Paris recently I was very much surprised to see that Free Mobile has an LTE carrier in the European Digital Dividend II 700 MHz band on air. In Germany, this band was also auctioned to network operators back in 2015 but there are no deployments so far. At first I thought this might be a mistake on my part or a that I stumbled over a test cell. Some more digging revealed, however, that Free has really taken the band into operation. According to the Wikipedia LTE Networks in Europe page, DNA in Finland has also started using the band. Is anyone aware of any other European network operator that has started using 700 MHz spectrum?

Continue reading LTE 700 MHz In Action In Paris As Band 28

Today I have a documentary recommendation about personal computing in the 1980s that requires a bit of an intro to set it into perspective:

In the first half of the 1980s the world of personal computers was separated into home and office computing. In both camps, many companies competed for market share. On the home computer front Commodore, Atari and Apple where among the most successful companies with their C64, Atari 800 and the Apple II computers. Office computing on the other hand was dominated by the IBM PC launched in 1981, PC compatible computers of clone manufacturers and also the Apple II. Often, this multitude is reduced to a power struggle between Apple, IBM and Microsoft but this is only part of the story.

Continue reading From Bedrooms To Billions – The Amgia Years

I really like the Raspberry Pi platform as it gives me full Linux flexibility for many of my projects. The platform’s limit, however, is networking, as a Pi only has a single 100BaseT Ethernet interface. Yes, it can be extended via additional USB/Ethernet interfaces and I’ve done so in the past but it’s a bit of a kludge and one is still limited to 100BaseT (due to USB2). For network centric projects I’ve long been looking for another hardware platform that would give me similar Linux flexibility but I haven’t found anything useful. That is, until now!

Continue reading Routing With Linux At The Edge: The Ubiquiti ERX

Once upon a time, emergency calls were a simple thing in GSM networks. It was agreed that 112 and 911 would be universal emergency call numbers anywhere. When the user dials those numbers an Emergency Call Setup is made without the dialed number. The call is then given priority by the network and is routed to the next emergency response center. But that was back in 1991. In the meantime a number of additional sources of emergency call numbers and additional functionality has been added to the 3GPP standards. One addition was to store additional emergency call numbers on the SIM card which would also trigger an emergency call setup. And probably again a bit later another addition was standardized that lets the network inform devices about additional numbers.

Continue reading Network Provided Emergency Numbers

If you like creating backup images of the SD cards used for your Raspberry Pi projects with ‘dd’ you’ve probably come across the problem that the image file has the same size as the SD card. Storing such large files becomes expensive over time and restoring them to an SD card takes a long time. It would be much better if the image file only had the size of the files while still being restorable to SD cards as before. Recently I’ve come across a project on Github that does just that.

Continue reading Shrinking Raspberry Pi Images

After test driving the Mkrfox 1200 Arduino with Sigfox functionality on board and giving an introduction to programming in the previous two parts it’s time now to have a closer look at some of the basic parameters of a Sigfox network to get an idea of the capabilities and constraints, what that means for devices and applications using the network.

Continue reading The Sigfox Arduino – Part 3 – Sigfox Network Basics

In the first part of this series on the Mkrfox 1200 Arduino that comes with a Sigfox chip and a 2 year network subscription I’ve taken a look at what is required to get going, how to send a first message from the module to the network and how that message can be forwarded to a server on the Internet. In total it was a 30 minutes exercise, i.e. very easy to do. In this part, I’ll have a closer look at the code that is required to accomplish the task.

Continue reading The Sigfox Arduino – Part 2 – Program To Send A Message

After reading about the MKRFOX 1200 Arduino with built in Sigfox connectivity and a 2 year subscription for 50 Euros (including VAT and shipping), I ordered one right away and was pleasantly surprised that it arrived only a few days later. This and the following posts document my first impressions and give a basic overview of Sigfox devices, the network, the back end server and their capabilities.

Continue reading The Sigfox Arduino – Part 1 – First Impressions

Back in April I wrote a post about a breakthrough Arduino board with a Sigfox chip bundled with a 2 year network subscription. It has since arrived and a number of posts about how it performs in practice will come soon. In the initial post I wrote that in my opinion that’s where 3GPP network operators have to go as well with NB-IoT to drive adoption. Actually NB-IoT seems to be closer to this goal than I initially thought. In the Netherlands, Sodaq is working on a NB-IoT Arduino shield and has started a Kickstarter campaign to get funding for it.

Continue reading An NB-IoT Shield That Includes A 1 Year T-Mobile NL Subscription