Scott Hanselman

How to use a Raspberry Pi 4 as a Minecraft Java Server

September 7, '20 Comments [12] Posted in Gaming
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imageMy 14 year old got tired of paying $7.99 for Minecraft Realm so he could host his friends in their world. He was just hosting on his laptop and then forwarding a port but that means his friends can't connect unless he's actively running. I was running a Minecraft Server in a Docker container on my Synology NAS but I thought teaching him how to run Minecraft Server on a Raspberry Pi 4 we had lying around would be a good learning moment.

First, set up your Raspberry Pi. I like NOOBS as it's super easy to setup. If you want to make things faster for setup and possibly set up your Pi without having to connect a monitor, mouse, or keyboard, mount your SSD card and create a new empty file named ssh, without any extension, inside the boot directory to enable ssh on boot. Remember the default user name is pi and the password is raspberry.

SSH over to your Raspberry Pi. You can use Putty, but I like using Windows 10's built-in SSH. Do your standard update stuff, and also install a JDK:

sudo apt update
sudo apt upgrade
sudo apt install default-jdk

There are other Minecraft 3rd party Java Servers you can use, the most popular being Spigot, but the easiest server you can run is the one from Minecraft themselves.

Go to in a browser. It'll say something like "Download minecraft_server.1.16.2.jar and run it with the following command." That version number and URL will change in the future. Right-click and copy link into your clipboard We are going to PASTE it (right click with your mouse) after the "wget" below. So we'll make a folder, download the server.jar, then run it.

cd ~
mkdir MinecraftServer
cd MinecraftServer
java -Xmx2500M -Xms2500M -jar server.jar nogui

You'll get a warning that you didn't accept the EULA, so now open "pico eula.txt" and set eula=true, then hit Ctrl-X and Yes to save the new file. Press the up key and run your command again.

java -Xmx2500M -Xms2500M -jar server.jar nogui

You could also make a text file with pico then chmod +x to make it an easier single command way to start your server. Since I have a Raspberry Pi 4 with 4g gigs of RAM and it'll be doing just this one server, I felt 2500 megs of RAM was a sweet spot. Java ran out of memory at 3 gigs.

You can then run ifconfig at and command line and get your Pi's IP address, or type hostname to get its name. Then you can connect to your world with that name or ip.

Running Minecraft Servers

Performance Issues with Complex Worlds

With very large Minecraft worlds or worlds like my son's with 500+ Iron Golems and Chickens, you may get an error like

[Server Watchdog/FATAL]: A single server tick took 60.00 seconds (should be max 0.05)

You can workaround this in a few ways. You can gently overclock your Pi4 if it has a fan by adding this to the end of your /boot/config.txt (read articles on overclocking a Pi to be safe)


And/or you can disable the Minecraft internal watchdog for ticks by setting max-tick-time to -1 in your server's file.

We solved our issue by killing about 480+ Iron Golems with

/kill @e[type=minecraft:iron_golem]

but that's up to you. Just be aware that the Pi is fast but not thousands of moving entities in Minecraft fast. For us this works great though and is teaching my kids about the command line, editing text files, and ssh'ing into things.

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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CoreBoy is a cross platform GameBoy Emulator written in C# that even does ASCII

April 23, '20 Comments [11] Posted in DotNetCore | Gaming | Open Source
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.NET and C# are great languages for programming emulators. Specifically retrogaming and retroarcade emulators. In fact, there's a long history of emulators written in C#. Here's just a few.

Today, David Whitney is deep into writing CoreBoy, a GameBoy Emulator written in C# and .NET Core, using WinForms, and I also spy the Avalonia cross-platform open source WPF-like framework. Head over to and give the gent a STAR. It even has a headless mode and you could use it as a Library in your own software. Who doesn't want a GameBoy library in their app?

I cloned and built it with Core in just a few minutes. Lovely. I enjoy a clean codebase. Assuming you have a backup of one of the many physical GameBoy games you own like me, you can load a binary dump in CoreBoy as a *.gb or *.gbc file and you'll get something this:

CoreBoy - Zelda Link's Awakening


Sweet! Sure it's a little buggy and slow but figuring these things out is the fun of it all! I love that David Whitney is taking us on this journey with him.

There's even already a MonoGame-based graphics surface using DesktopGL and "nilllzz" has it running on Ubuntu!

GameBoy Emulator in C# running on Ubuntu using MonoGame

Emulators are always fun projects to read and learn from. Here, David has a clear separation of concerns between the emulator (handling the CPU, loading instructions, etc.) and the graphics surface that is ultimately responsible for putting pixels on screen.

It looks like he hasn't got it working yet (some issues with command line parsing), but in a few minutes with a little hard-coding I was able to switch to ASCII mode with David's SillyAsciiArtCreator that takes a Pixel and RGB value and maps it to ASCII art that looks awesome in the Windows Terminal.

Zelda in a GameBoy Emulator as ASCII Art

Which is kind of awesome. Why would you do this? BECAUSE YOU CAN

Zelda in a GameBoy Emulator as ASCII Art

I look forward to seeing what comes of this cool new emulator and I'll be reading its code in more detail in the weeks to come! Great stuff, David!

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Retrogaming by modding original consoles to remove moving parts and add USB or SD-Card support

January 29, '20 Comments [8] Posted in Gaming
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I'm a documented big fan of Retrogaming (playing older games and introducing my kids to those older games).

For example, we enjoy the Hyperkin Retron 5 in that it lets us play NES, Famicom, SNES, Super Famicom, Genesis, Mega Drive, Game Boy, Game Boy Color, & Game Boy over 5 category ports. with one additional adapter, it adds Game Gear, Master System, and Master System Cards. It uses emulators at its heart, but it requires the use of the original game cartridges. However, the Hyperkin supports all the original controllers - many of which we've found at our local thrift store - which strikes a nice balance between the old and the new. Best of all, it uses HDMI as its output plug which makes it super easy to hook up to our TV.

I've also blogged about modding/updating existing older consoles to support HDMI. On my Sega Dreamcast I've been very happy with this Dreamcast to HDMI adapter (that's really internally Dreamcast->VGA->HDMI).

The Dreamcast was lovely

When retrogaming there's a few schools of thought:

  • Download ROMs and use emulators - I try not to do this as I want to support small businesses (like used game stores, etc) as well as (in a way) the original artists.
  • Use original consoles with original cartridges
  • Use original consoles with backup images through an I/O mod.
    • I've been doing this more and more as many of my original consoles' CD-ROMs and other moving parts have started to fail.

It's the failure of those moving parts that is the focus of THIS post.

For example, the CD-ROM on my Panasonic 3DO Console was starting to throw errors and have trouble spinning up so I was able to mod it to load the CD-ROMs (for my owned discs) off of USB.

This last week my Dreamcast's GD-ROM finally started to get out of alignment.

Fixing Dreamcast Disc Errors

You can can align a Dreamcast GD-ROM by opening it up by removing the four screws on the bottom. Lift up the entire GD-ROM unit without pulling too hard on the ribbon cable. You may have to push the whole laser (don't touch the lens) back in order to flip the unit over.

Then, via trial and error, turn the screw shown below to the right about 5 degrees (very small turn) and test, then do it again, until your drive spins up reliably. It took me 4 tries and about 20 degrees. Your mileage may vary.

The Dreamcast GD-ROM just pops outTake out the whole GD-ROM

Turn this screw to align your laser on your Dreamcast

This fix worked for a while but it was becoming clear that I was going to eventually have to replace the whole thing. These are moving parts and moving parts wear out.

Adding solid state (SD-Card) storage to a Dreamcast

Assuming you, like me, have a VA1 Dreamcast (which is most of them) there are a few options to "fake" the GD-ROM. My favorite is the GDEMU mod which requires no soldering and can be done in just a few minutes. You can get them directly or on eBay. I ordered a version 5.5 and it works fantastically.

You can follow the GDEMU instructions to lay out a FAT32 formatted SD Card as it wants it, or you can use this little obscure .NET app called GDEMU SD Card Maker.

The resulting Dreamcast now has an SD Card inside, under where the GD-ROM used to be. It works well, it's quiet, it's faster than the GD-ROM and it allows me to play my backups without concern of breaking any moving parts.

Modded Dreamcast

Other small Dreamcast updates

As a moving part, the fan can sometimes fail so I replaced fan my using a guide from iFixit. In fact, a 3-pin 5V Noctua silent fan works great. You can purchase that fan plus a mod kit with a 3d printed adapter that includes a fan duct and conversion gable with 10k resistor, or you can certainly 3D print your own.

If you like this kind of content, go follow me on Instagram!

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Visual Studio for Nintendo Switch? - FUZE4 Nintendo Switch is an amazing coding app

October 10, '19 Comments [4] Posted in Gaming
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I love my Nintendo Switch. It's a brilliant console that fits into my lifestyle. I use it on planes, the kids play it on long car rides, and it's great both portable and docked.

NOTE: Check out my blog post on The perfect Nintendo Switch travel set up and recommended accessories

But I never would have predicted "Visual Studio Core for Nintendo Switch" - now that's in a massive pair of air quotes because FUZE4 Nintendo Switch has no relationship to Microsoft or Visual Studio but it's a really competent coding application that works with USB keyboards! It's an amazing feeling to literally plug in a keyboard and start writing games for Switch...ON A SWITCH! Seriously, don't sleep on this app if you or your kids want to make Switch games.

Coding on a Nintendo Switch with FUZE4 Switch

Per the Fuze website:

This is not a complex environment like C++, JAVA or Python. It is positioned as a stepping stone from the likes of Scratch , to more complex real-world ones. In fact everything taught using FUZE is totally applicable in the real-world, it is just that it is presented in a far more accessible, engaging and fun way.

If you're in the UK, there are holiday workshops and school events all over. If you're elsewhere, FUZE also has started the FuzeArena site as a forum to support you in your coding journey on Switch. There is also a new YouTube channel with Tutorials on FUZE Basic starting with Hello World!

FUZE4 includes a very nice and complete code editor with Syntax Highlighting and Code bookmarks. You can plug in any USB keyboard - I used a Logitech USB keyboard with the USB wireless Dongle! - and you or the children in your life can code away. You just RUN the program with the "start" or + button on the Nintendo Switch.

It can't be overstated how many asserts, bitmaps, sample apps, and 3D models that FUZE4 comes with. You may explore initially and mistakenly think it's a shallow app. IT IS NOT. There is a LOT here. You don't need to make all the assets yourself, and if you're interested in game makers like PICO8 then the idea of making a Switch game with minimal effort will be super attractive to you.

Writing code with FUZE4
3D Demos with FUZE4 Lots of Programs come with FUZE4 Nintendo Switch
Software Keyboard inside FUZE4 Get started with code and FUZE4

FUZE and FUZE Basic also exists on the Raspberry Pi and there are boot images available to check out. It also supports the Raspberry Pi Sense Hat add-on board.

They are also working on FUZE4 Windows as well so stay turned for that! If you register for their forums you can also check out their PDF workbooks and language tutorials. However, if you're like me, you'll have more fun reading the code for the included samples and games and figuring things out from there.

FUZE4 on the Nintendo Switch is hugely impressive and frankly, I'm surprised more people aren't talking about it. Don't sleep on FUZE4, my kids have been enjoying it. I do recommend you use an external USB keyboard to have the best coding experience. You can buy FUZE4 as a digital download on the Nintendo Shop.

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Emulating a PlayStation 1 (PSX) entirely with C# and .NET

September 12, '19 Comments [15] Posted in Gaming | Open Source
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I was reading an older post in an emulator forum where someone was asking for a Playstation 1 (PSX) emulator written in C#, and the replies went on and on about how C# and .NET are not suited for emulation, C# is far too slow, negativity, blah blah.

Of course, that's silly. Good C# can run at near-native speed given all the work happening in the runtime/JITter, etc.

I then stumbled on this very early version of a PSX Emulator in C#. Now, if you were to theoretically have a Playtation SCPH1001.BIN BIOS and then physically owned a Playstation (as I do) and then created a BIN file from your physical copy of Crash Bandicoot, you could happily run it as you can see in the screenshot below.

Crash Bandicoot on a C#-based PSX Emulator

This project is very early days, as the author points out, but I was able to Git Clone and directly open the code in Visual Studio 2019 Community (which is free) and run it immediately. Note that as of the time of this blog post, the BIOS location *and* BIN files are hardcoded in the CD.cs and BUS.cs files. I named the BIN file "somegame.bin."

PSX Emualtor in C# inside Visual Studio

A funny note, since the code is unbounded as it currently sits, while I get about 30fps in Debug mode, in Release mode the ProjectPSX Emulator runs at over 120fps on my system, emulating a PlayStation 1 at over 220% of the usual CPU speed!

Just to make sure there's no confusion, and to support the author I want to repeat this question and answer here:

Can i use this emulator to play?

"Yes you can, but you shouldn't. There are a lot of other more capable emulators out there. This is a work in progress personal project with the aim to learn about emulators and hardware implementation. It can and will break during emulation as there are a lot of unimplemented hardware features."

This is a great codebase to learn from and read - maybe even support with your own Issues and PRs if the author is willing, but as they point out, it's neither complete nor ready for consumption.

Again, from the author who has other interesting emulators you can read:

I started doing a Java Chip8 and a C# Intel 8080 CPU (used on the classic arcade Space Invaders). Some later i did Nintendo Gameboy. I wanted to keep forward to do some 3D so i ended with the PSX as it had a good library of games...

Very cool stuff! Reading emulator code is a great way to not only learn about a specific language but also to learn 'the full stack.' We often hear Full Stack in the context of a complete distributed web application, but for many the stack goes down to the metal. This emulator literally boots up from the real BIOS of a Playstation and emulates the MIPS R3000A, a BUS to connect components, the CPU, the CD-ROM, and display.

An emulator has to lie at every step so that when an instruction is reached it can make everyone involved truly believe they are really running on a Playstation. If it does its job, no one suspects! That's why it's so interesting.

You can also press TAB to see the VRAM visualized as well as textures and color lookup tables which is super interesting!

Visualizing VRAM

One day, some day, there will be no physical hardware in existence for some of these old/classic consoles. Even today, lots of people play games for NES and SNES on a Nintendo Switch and may never see or touch the original hardware. It's important to support emulation development and sites like with Donations to make sure that history is preserved!

NOTE: It's also worth pointing out that it took me about 15 minutes to port this from .NET Framework 4.7.2 to .NET Core 3.0. More on this, perhaps, in another post. I'll also do a benchmark and see if it's faster.

I encourage you to go give a Github Star to ProjectPSX and enjoy reading this interesting bit of code. You can also read about the PSX Hardware written by Martin Korth for a trove of knowledge.

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.