JotaleaOS is an open source, minimalistic, experimental operating system made by Jotalea, designed for extreme low-resource environments. It does not support external programs or games, as it lacks a standard application execution environment. The system is entirely self-contained, running only its built-in commands.
↫ JotaleaOS website
Exactly what is says on the tin: a tiny operating system created entirely as a learning experience. That’s it.
I’ve used OSes that do more than this in 2K, let alone 2Mb; I’m not sure why the system requirements are so excessive.
I haven’t had a chance to run it but I had a quick look at the source code and it’s about 150 lines of assembly (or a shade over 200 lines including comments and empty lines). The source code file itself is 6kB.
It looks like it should run in well under 2kB. Perhaps the 2MB requirement is future-proofing for more commands and/or a filing system.
This is not an operating system by any stretch.
I agree with Nico57 above. While interesting, this is not an operating system.
Not sure about this one, bub! I mean, can this really be called an operating system?
It’s indeed not an operating system. It’s a trivial command prompt application with just a few simple commands.
I read the entire code. It’s an x86 boot sector that uses BIOS routines for reading keystrokes and displaying text. It has a very simple command prompt with only some trivial commands (echo, changing the prompt, clear the screen, help and halt).
The code has several bugs, e.g. there is no bounds checking, so if you try and change the prompt to something longer, you’ll overwrite some of the other strings.
The real system requirements are essentially any x86. It should run on an original 8086 CPU from 1978, and uses only 512 bytes of RAM.
There are far more interesting projects that do interesting things within a 512 byte x86 boot sector. Here’s a list of boot sector games, for example: https://gist.github.com/XlogicX/8204cf17c432cc2b968d138eb639494e
Or other examples of more useful things that are far more like operating systems, and fit in such a tiny code size, would be machine monitors like WozMon on the Apple 1, … Yes, those aren’t operating systems either, but they come a lot closer.
Is MS-DOS an operating system ?
Yes, MS-DOS is an operating system.
Wikipedia uses the following definition: “An operating system (OS) is system software that manages computer hardware and software resources, and provides common services for computer programs.”
MS-DOS certainly does that. It sets up hardware, allows running other software (multi-tasking is not a requirement!), and provides common services, e.g. via the INT 21h software interrupt.