NetBSD 10.x kernel MATH_EMULATION
This is my battle-worn, falling-apart laptop rocking an #i486SX CPU from the early ’90s. It’s so ancient that it doesn’t even have an FPU (Actually, that’s not true, they just cut-out FPU from i486DX to make CPU cheaper)! Anyway, I’ve always dreamed of running a modern UNIX-like OS on it.
So, I spent some time resurrecting math emulation in the #NetBSD-10.x kernel, and guess what? I did it! But here’s the kicker—the very moment I finished compiling the kernel, ready to test my work, my laptop decided to stop recognizing the Enter key. Just like that. Now, I have no idea if my FPU emulation actually works or not!
So, #retrocomputing folks—if anyone out there has an i486SX machine and is willing to give this a spin, I’d really appreciate it!
UPD: 11.03.2025: Significant progress
UPD: 31.03.2025: Results delivered to the user
Today the simple, yet correct, calculation results were successfully delivered to the user!
UPD 2025.04.27:🚀 First Release is Here! 🚀
I’m excited to announce the first release of i486SX_soft_FPU — a software FPU emulator for the classic Intel 486SX CPU, running on NetBSD 10!
This project brings floating-point support back to life for 486SX machines, even though modern NetBSD versions no longer natively support processors without a hardware FPU.
If you’re into retrocomputing, operating system hacking, or just love old-school hardware, check it out!
👉 Project page: https://github.com/mezantrop/i486SX_soft_FPU
Contributions, feedback, and testing are all very welcome!
Let’s keep these vintage machines alive! 🔥🖥️
#retrocomputing #NetBSD #486SX #opensource
UPD 2025.05.03: 86Box
Just successfully tested #NetBSD-10.1 with #i486SX #FPU_emulation on #86Box
#486SX #86Box #FPUEmulation #FPUEmulation #i486SX #NetBSD #opensource #retroComuting #retrocomputing
Wow, @linux does actually improve efficiency over time...
I just compiled a minimal kernel 6.5 for OS/1337 targeting #i486 instead of #i686 and the resulting binary is even 10kB smaller than the one for 6.4.12...
For real: That's awesome cuz it allows me to make the #Floppy version for #486SX a reality and still have #Toybox & #dropbear as #SSH client in it...
Cudos to @torvalds and the maintainers for that:
They really did cleanup the codebase and made it #smol|ler!
Attached: 1 image Just 66.232 bytes left of 1440kB... But already this is pretty nifty and will at least allow OS/1337 "#Floppy Edition" to be more versatile than #Floppinux by being a basic #SSH client [thanks to #dropbear] so it can at least be used to SSH into stuff... #OS1337 https://github.com/OS-1337/OS1337/commit/09534203e2a6e48b4bf5a8b9869d4de962ee0d02
So for those asking, the #1440kB #Floppy Version of OS/1337 will be a better #Floppinux with #Ethernet & #Network support and packing in #Dropbear as #SSH client.
So you could at the very least use it as a #SSH #Terminal #distro...
Sadly this means it will require at least an #i686 and won't run on an #i486 anymore as a lot of memory was eaten up by #486SX workaround code in the kernel...
Admiral Shark
Arcturax 🦇
#define me human
Kevin Karhan 
Silicium