Author: Martin

A book that’s been on my reading list for quite some time was ‘Flatland’ by Edwin A. Abbott. Published in 1884, it’s available as ePub on Project Gutenberg, unless you live in Germany and don’t have a VPN to get around them blocking their library for Germany. I got interested in Flatland because I heard several times that it is an interesting story of how a two dimensional being that exists as a square and living in Flatland is introduced to the third dimension by a sphere. Perhaps, I thought, I could learn something about being limited to three dimensions and how to approach a 4th dimension!?

Continue reading Book Review – Flatland – “Upward, not Northward”

It’s been a classic this week: I was just about to start giving a lecture when I noticed that my servers at home were suddenly not reachable anymore over my main (VDSL) backhaul link. The lecture begins and no way to investigate what is going on… Well at least I knew that my backup connectivity would come up and service is restored automatically.

I noticed during the lecture that the DSL link came back into service and when I checked a bit later what was going on, I was surprised to see that VDSL vectoring had been activated on my line. As I keep making screenshots of the connection parameters of my line to see how things change over time, I noticed a number of interesting things.

Continue reading My DSL Line Has Been Vectorized

Back in the 1980s, I had, like many other teenagers, a home computer and, yes, I also used it for playing games. Recently, when I listened to episode 170 of Retro Computing Roundtable, they were talking about ‘Paradroid’ on the C64. It must have only been a side note because it didn’t even make it into the show notes and I had no immediate recollection of how the game looked like back then or how it worked. However, I instantly knew that I was really addicted to this game back then. I couldn’t visualize it anymore, I didn’t remember how the game was played but I still remembered that I spent hours playing it. Strange how the brain works.

Continue reading Paradroid Today

And a quick service announcement today. Due to recently announced ownership changes at Github, I’ve decided to move my open source software repositories I had there for many years over to GitLab. At 250k projects per day that are moving, I seem to be not the only one. So long Github, and thanks for all the fish!

In part 6, I’ve been musing a bit about the inter-play between Connection-, Registration- and Session Management. In this part, let’s have a closer look at Session Management and in particular at the standard features that are required for mobile Internet access.

Continue reading The 5G Core – Part 7 – More About Session Management

Since we moved a step closer last year to a single European telecommunication market by (almost) treating voice calls and data use in the EU the same as in the home country, traveling in the EU has become so much more convenient. No need anymore for local pre-paid SIMs, extra phones and cumbersome setup procedures to keep costs down. But even a small step outside what is currently included painfully reminds one that we are nowhere near a single telecommunication market yet and network operators are using every opportunity to massively overcharge for their services. Continue reading The Week of Expensive Roaming Mistakes

I’m from the generation that grew up just after punch cards, punched tape and mainframe computers went out of fashion and gave way to interactive programming in front of a terminal or, in my case, a computer at home. So while I was generally aware of the principle of feeding programs and data to mainframes and minis this way, I only had a hazy idea of how programs were encoded on the cards. Recently, a friend gave me a book about Assembler programming written in 1973 which did not only explain in some detail some of the machine instructions of a 1960/70 mainframe but also how Assembly language programs ended up on punch cards and finally in the memory of the computer.

Continue reading A Book About Assembler Programming from 1973 and Punch Cards

If it is not the first time you come across this blog you are probably aware that I host most of the cloud services I use on (now virtual) servers at home. To make sure my Nextcloud and other services are always available when my main connectivity over DSL fails, I have backup LTE connectivity that can take over automatically. There is one major issue with that however: I can’t access my servers from the mobile network. Continue reading Moving from Amazon to Hetzner

Today lets have a look at how the 5G Core (5GC) does Connection-, Registration- and Session-Management for 5G devices. As in the previous posts, the procedures are described in 3GPP TS 23.501 which is the 5G analog to the 4G LTE core network description in 3GPP TS 23.401. I guess the similar number is no coincidence.

Continue reading The 5G Core – Part 6 – Connection-, Registration- And Session Management

A quick observation today about people coming to meetings with their tablets rather than their Windows based notebooks. So far my crude analysis was that those are the people in companies that mostly need a screen to access and consume information. To them, a keyboard for typing in longer texts quickly and efficiently is a rather optional thing, especially in meetings. But there is one more thing Windows notebooks like to do, especially if they are centrally administered: Not do what you want, especially when you use them to present something during a meeting.

Continue reading Windows Notebooks No Longer Fit For Their Purpose In Meetings