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site iconAndreasModify

Electrical engineer, musician, out and about on two wheels, read a lot of books, coffee-addict.
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Running Unix V4 from 1974

2025-12-22 08:00:00

A few weeks ago a copy of Unix V4 which was thought to be lost was discovered on a storage tape at the University of Utah. It was then sent to the Home Computer Museum in California, and well, they managed to read it out and put its contents on the Internet Archive.

I haven't seen any news articles about this yet, but fellow Mastodonian Flexion gave it a try and posted about it, which is how I came across this. So I had to try it, too.

Thankfully someone put up a tutorial with the necessary files here. All that's needed is a pdp11 emulator. I'm using the one from the Open SIMH project which I could easily download on Arch Linux from the repos, it's just called simh.

And from there it was just a matter of following the tutorial. I had to get four files:

  • unix_v4.tap
  • disk.rs
  • install.ini
  • boot.ini

I put them all in the same folder and started the pdp11 emulator with the ini script:

$ simh-pdp11 install.ini

Then I followed the tutorial by typing out the following commands:

=mcopy
'p' for rp; 'k' for rk
k
disk offset
0
tape offset
75
count
4000
=uboot
k
unix
mem = 64530

login: root
# sync
# sync
# sync
# ^E        ; end emulation

After Ctrl+E the emulator can be quit with Ctrl+C and then restarted with the boot script:

$ simh-pdp11 boot.ini

After typing k and unix I got the login prompt and could log in as root:

k
unix
mem = 64530

login: root
#

And there we go, Unix V4 from 1974!

So what can we do with that?

Honestly, I have no idea. Not too much probably, but it's really cool to explore and just to see it running. This system is almost a decade older than I am, and it feels kind of alien and still familiar at the same time. It was made at a time when computers were the size of refrigerators and often didn't even have monitors yet but instead printed their output on a piece of paper. And yet It's the ancestor to all modern day Unix systems (including MacOS) and also at least the spiritual ancestor to Linux, and that's exacty what it feels like using it. Like an early version of these systems. Relatively primitive and missing a lot of features that make using the modern systems easy, but definitely familiar.

It's fascinating to see how much it has changed in the last 50 years, but also how much has stayed the same. It's a bit like driving in a car from the 60s or 70s. They are incredibly barebones by today's standards, but still unmistakably just an earlier version of what we have today and if you know how to drive a modern car, you will also be able to drive one from 1974, just like you are able to navigate around a Unix system from 1974 if you're familiar with it's modern descendants.

Linkdump No 86

2025-12-19 08:00:00

an animated 90s style GIF that has the word Links in green font on black background

In 1981, a new TV station dedicated to playing music videos appeared in the US. It famously started its programme by playing The Buggles' Video Killed the Radio Star. In 1987, MTV Europe began its broadcast with an equally fitting video: the Dire Straits song Money for Nothing, which opens with the line "I want my MTV", sung by Sting. I was too young to have been around for this, but I remember watching MTV and its German counterpart VIVA a lot when they were at their peak during my teenage years in the 90s.
I also remember them playing less and less music and more and more "reality TV" shows in the 2000s, which caused me (and everybody else) to lose interest in watching them. Today, VIVA has been dead for years, and now MTV at least over here will stop playing music altogether, which means its spirit is also gone. Nothing lasts forever I guess, and since YouTube appeared on the scene this development was probably inevitable, but it's still kind of sad to see. Today of course you can see any music video you like at any time online, but it's just not the same, is it? Rest In Peace, MTV!


Articles

  • MTV without music videos from January
    From next year on, MTV Germany will stop airing music videos altogether and instead focus on broadcasting US reality shows. Signs of our times I guess... It's not like MTV had any kind of cultural relevance for the past 20 years or so, but this is still sad.
  • Why your early 2000s photos are probably lost forever
    If you have an old digicam, smartphone or old memory cards with pictures on it that you haven't backed up yet, now is probably a good time to do so, because these things don't last forever and once they die, your photos will be gone. (via)

Software/Services

  • PCjs Machines
    I'm not entirely sure how to describe this... it's a collection of emulators for old systems and programs that run right in the browser. The focus is on systems from the 80s and early 90s, so if that's your kind of thing, have a look!
  • BetaWiki
    A wiki dedicated to compiling information about different builds of popular operating systems and other software.

Videos

Around the Small Web

  • Ad Blockers helped kill the open web | Christian Heilmann
    This is an interesting post about how it came to be that the web is drowning in ads these days. I'm not sure I agree with his conclusion that adblockers are to blame for so much of what we're seeing today, I think it would have happened regardless. But it's interesting food for thought, and a nudge towards making sure we pay for the things that bring us value.

Misc

Building and running Linux off a Floppy Disk with Floppinux

2025-12-14 08:00:00

I'm currently trying to get a little deeper into Linux and understand more what actually makes the OS tick under the hood. I've been using Linux for almost 20 years at this point, but how the Kernel works and how everything is put together so that a functioning operating system comes out of it is still somewhat of a mystery to me.

There is a project called "Linux From Scratch", which is essentially a tutorial that does a great job describing the process of compiling a working Linux system, well, from scratch. I'm currently working through it, but it's pretty extensive and it takes a while to get through if you're really trying to understand what you're doing and aren't just blindly copying commands.

Thanks to a recent YouTube video by Action Retro I found the perfect project to get into this sort of thing: Floppinux, a tutorial to create a working Linux distro of sorts that can boot from a single floppy disk and can run on hardware as low spec as a 33 MHz 486 CPU.

The tutorial does a great job guiding you through all the steps necessary to build a bootable Linux installation from scratch that is so tiny that it fits on a 1.44MB floppy disk.

You start by downloading the kernel sources and configuring the kernel with a bare minimum config that is just enough to make the system work, but as a result it's also super lightweight with the compiled kernel only taking up around 830KB of space.

Booting just the kernel is kind of useless though, so some utilities are needed to turn this into a working system (utilities like ls, rm, echo, vi, cat and so on). For this, Busybox is used which is a collection of lightweight utilities compiled into a single binary. Busybox is primarily meant to be used in embedded devices where there's a limited amount of storage and memory available and as such is perfect for this project. You also need a cross compiler to build Busybox for the target architecture (32 bit 486) on your modern 64 bit system.

After compiling the kernel and the Busybox utilities you create a floppy disk image, install a filesystem and bootloader (syslinux, another very lightweight tool) inside this image, copy the kernel and the Busybox utilities into the image, configure a few things and then you're done. You just created a minimal Linux system that fits on a single floppy disk.

This image can then be tested inside an emulator like qemu or 86Box, or written to a floppy disk and be booted on real hardware. And so that's what I did. I happen to have a USB floppy drive lying around that I bought on Ebay years ago, along with a few floppy disks, and so I dumped the image to a floppy disk, connected it to my Eee PC, set it to boot from the floppy drive, and... nothing.

The image booted fine in qemu and 86Box, but it didn't get past the syslinux boot prompt on real hardware. I tried it on a different PC,wrote the floppy again, but the same thing happened every time. Maybe booting from a USB floppy drive doesn't work the same as booting from an internally connected floppy drive? I don't have a PC with an internal floppy drive anymore, so I thought I was out of luck here, until I decided to try a different floppy disk, and then it worked! Turns out 30 year old floppy disks can go bad. Who could have known.

And there is, a netbook booted from a floppy disk and running a Linux distro I created myself (following a tutorial of course). I have to say, that feels pretty satisfying! There's still an error mounting the floppy disk itself, probably because it's connected via USB and doesn't show up under /dev/fd0 as expected. I'd probably have to compile the kernel with USB or SATA support enabled, but then I think I would run out of space pretty quickly, so I didn't bother.

Is it useful? Probably not... you'd need a bit more software to make this into a system that can actually do anything, at least drivers for some external storage and maybe network access, but there's only so much space on a single floppy disk. Booting from floppy is also insanely slow. I had forgotten how slow floppy disks are, but let me remind you: they're very slow! Booting a system that's just a bit over a megabyte in size takes almost a minute. When it's booted however it's perfectly responsive because it runs from ram and never needs to access the floppy again.

So even if the usefulness is pretty limited, at least if you stick to the utilities that are mentioned in the tutorial, it's still a great learning exercise and a great demonstration of how much (or how little) is really needed to get a functioning Linux system. And of course it's a good starting point if you want to flesh it out and install some actually useful software in there. You might be better off booting from a USB drive then, obviously. If you're looking to understand Linux a bit better, I highly recommend having a look at Floppinux.


I have to mention though that I came across a few errors in the tutorial, which causes the system to be mostly functional, but a few things aren't working right that have to do with mounting the proc and sys filesystems of the Kernel. I spent a bit of time figuring out why it wasn't working and wrote a bug report on the project's Github page. I'm also going to reproduce what I wrote here. Hopefully this will be included in the tutorial in the future.

So if you want to follow the tutorial and build the system yourself, make the following changes:

  • The git clone call for the kernel contains an error
    • Wrong: git clone --depth=1 --branch v6.14.y https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
    • Right: git clone --depth=1 --branch v6.14.11 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
  • The init rc script expects ln and mkdir to be present, so these need to be included in busybox (add them via the busybox menu config)
  • The first two setup paths for the cross compiler setup are missing a / after "${BASE}":
    • Wrong: sed -i "s|.*CONFIG_CROSS_COMPILER_PREFIX.*|CONFIG_CROSS_COMPILER_PREFIX="\"${BASE}"i486-linux-musl-cross/bin/i486-linux-musl-\"|" .config
    • Right: sed -i "s|.*CONFIG_CROSS_COMPILER_PREFIX.*|CONFIG_CROSS_COMPILER_PREFIX="\"${BASE}"/i486-linux-musl-cross/bin/i486-linux-musl-\"|" .config
    • Wrong: sed -i "s|.*CONFIG_SYSROOT.*|CONFIG_SYSROOT=\""${BASE}"i486-linux-musl-cross\"|" .config
    • Right: sed -i "s|.*CONFIG_SYSROOT.*|CONFIG_SYSROOT=\""${BASE}"/i486-linux-musl-cross\"|" .config

I also added /proc file system support in the kernel menuconfig under File systems -> Pseudo file systems. Not sure if this is really necessary though.

Linkdump No 85

2025-12-12 08:00:00

an animated 90s style GIF that has the word Links in green font on black background

Sometimes, the intros to these linkdumps almost write themselves; there is something in the links that gives me an idea or just a random thought that comes into my head and that I feel is worth writing down. Other times, nothing comes to my mind, no matter how hard I try. Today is one of those times. And you know what? Rather than waste more time trying to come up with something witty, I think it's okay if we go straight to the links today.


Articles

Software/Services

  • FLOPPINUX - An Embedded 🐧Linux on a Single 💾Floppy
    Can you build a Linux that fits and runs off of a single floppy disk? The answer surprisingly is yes, even in 2025. This is a great tutorial on how to compile a Linux that fits on a floppy. Youtuber Action Retro made a video about it, which is how I found this. There's a problem though - it doesn't work correctly. I went through the tutorial and I ran into the same issues he does in the video. Something with the mount command goes wrong. I haven't figured out what yet. Nevertheless, if you're interested in learning how to build a minimal working Linux system, it doesn't get simpler than this.
    Edit: I figured out what the issues were and wrote a bug report on the project's Github page. Hopefully these changes will be included in the tutorial in the future.

Hardware Projects

Videos

Around the Small Web

Misc

  • Vobis Denkzettel – Florians Retrokiste
    This is for the Germans (or German speakers) in the audience. Vobis was a computer retail chain which was huge in the 80s and 90s, and here's an extensive collection of their advertising flyers from those decades. If you want to know how much your parents paid for that shiny new Pentium 100 with 8 megs of RAM in 1996, you can look it up here. Remember - prices are in DM, not Euro. Here's an inflation calculator.

Linkdump No 84

2025-12-05 08:00:00

an animated 90s style GIF that has the word Links in green font on black background

Have you ever heard of Whamageddon? I hadn't, until the hashtag recently showed up in my Mastodon feed. According to the wiki site, it's a tongue-in-cheek survival game in which the player must avoid hearing Wham!'s Last Christmas from December 1st all the way through Christmas Eve. Unbeknownst to me, I've been playing this game for years, and not just with Last Christmas but also with Mariah Carey's All I want for Christmas is you (though I have to admit that I try to avoid hearing anything by Mariah Carey pretty much all year round). When I first heard these songs as a child they were nice, but after hearing them dozens, if not hundreds of times over the decades, they've kind of turned into the equivalent of the sound of fingernails scraping across a chalkboard for me. Which I also try to avoid having to listen to. Anyway, I'm happy that so far this year I haven't been Wham'd or Mariah'd yet, and I hope it stays this way. Wish me luck!


Articles

Software/Services

Videos

Around the Small Web

  • Kagi Small Web
    The Kagi search engine has a kind of discovery feed for small web blog posts. Every click on "Next Post" takes you to a new site. If you're looking to discover new blogs, give this one a try!
  • Is Pixelfed sawing off the branch that the Fediverse is sitting on?
    Apparently PixelFed, the Fediverse Instagram alternative is only showing posts from the Fediverse if they contain an image. On one hand this makes sense as the service is about viewing images, on the other hand as the author of this post points out this causes a Pixelfed user to not see posts from profiles they're following if they don't contain images, which could be a problem if Pixelfed takes off. According to an update to the post at the bottom, the Pixelfed dev seems to be working on a solution for this, so maybe that's a non-issue after all. (via)
  • Digital Minimalism: Using One Device for Everything | Welcome to The Privacy Dad's Blog!
    Here's an interesting exploration on two different approaches to digital minimalism: Using one device (aka smartphone) for everything vs using a bunch of single-purpose devices. Personally I gravitate much more to the single-purpose device approach, and it's interesting to read about his experiences using only one device.

Misc

  • PostHog – We make dev tools for product engineers
    I saw this mentioned in a news article - not interested in the company or the product, but the website design is great. They made it look like an operating system desktop, complete with movable windows, desktop icons and a trash can that contains a few funny things. It's really well done.

A roadmap of the Roman Empire

2025-11-30 08:00:00

For seven years in school I had the "pleasure" of learning Latin. I'm putting this in quotes because I didn't really like it, except maybe in the beginning. I was never really good at it and therefore didn't get very good grades, which was pretty demotivating. I loved learning English, as you might be able to tell, but Latin? Not so much. But what remained from learning Latin is a low key fascination with ancient Rome the Roman Empire. I'm not interested enough to really study the subject in depth, but I will occasionally read an article or watch a documentary about it.

Recently I came across a project called Itiner-e, which aims to create a database of all the roads of the entire Roman Empire. And since they have all this data, they made it available as an interactive map. Essentially, they created Google Maps of the Roman Empire.

Looking at this map gives you a good sense of just how enormous this empire was. It stretched from Scotland in the very north all the way to the middle east and deep into Egypt in North Africa. It's insane to think that an originally tiny republic in central Italy managed to conquer virtually half of Europe and keep it under its rule for centuries. And all of these huge distances over land were covered on foot or horseback (or horse-drawn carriages).

What's most fascinating to me though is that the Romans also attempted to conquer a land they called Germania. They didn't make it very far north due to the wilderness of the land and the resistance of the ancient Germans, but they managed to conquer most of the area south of the river Danube and a little beyond, which became the Roman province Raetia. Today of course this is South Germany. Where I grew up.

And indeed, if I zoom in on this area there's a dense network of roads there (keep in mind that only the main roads are shown), and one of them runs right past my hometown. Which I find absolutely fascinating.

It shouldn't really surprise me because there's a lot of Roman history in the area and many towns an cities date back to Roman times. For example, Augusta Vindelicum in the picture is modern day Augsburg. In addition to that, many places have a street called Römerstrasse (Roman street), which gives you a clue to the origin of that street. And in fact not one, but two villages near my hometown have such a Römerstrasse. Still, it's really fascinating to think that only about a kilometre (and about 2000 years) away from where I grew up there once was a Roman road, and probably some kind of settlement too, because they found some archaeological traces of a cemetery right next to where this road used to be.

Which makes me wonder what it used to look like back then. If I travelled back in time, would I recognise anything? Probably not as there aren't any old buildings left today that would be recognisable, and there aren't any unmistakable features in the landscape either. There's the Danube (the blue line in the picture), but this has been put into a channel centuries ago and looks nothing like it used to in ancient times. But it is known that the Romans built a bridge across the Danube in this area, so if I found that bridge and then continued on the road westwards, then maybe... I don't know. The Romans didn't backup their Instagram well enough, so sadly we have no pictures from this time period.

It's still fascinating to think that two thousand years ago, Roman soldiers and merchants travelled through the area where I used to play and explore as a child.