AstraOSThe kernel.
Written from scratch.
The kernel is the core of an operating system. It talks to the hardware – processor, memory, disks, USB – and decides which program may run when. We wrote ours ourselves: no Linux, no Windows inside. This page explains it simply.
- Size
- about 816 KB – smaller than many photos
- Memory (RAM)
- 64 MB for the system, 2 GB recommended for apps
- Processor
- normal PCs (x86/x64) today; a version for ARM computers is being built for the alpha
- Starts on
- old and new PCs (BIOS and UEFI)
- Tested in
- virtual computers on a PC – not yet on real hardware
- Code from others
- none in the kernel – only the small start program (Limine)
Why our own kernel?
Almost every operating system today is built on a core that is decades old. That has advantages – but every new idea has to fit around old decisions. We wanted to see how small, fast and secure a system can be when you build it new today, with security as the first rule.
For a few days in October we tried to build on Linux instead. Then we went back on purpose: AstraOS should be ours, from the first line to the desktop. The whole story is on the story page.
From switching on to the desktop
- The computer starts
The computer's firmware (BIOS or UEFI) starts a small start program (Limine). It loads the AstraOS kernel.
- The processor is set up
The kernel prepares the processor. Even if something goes badly wrong, you see a readable error screen instead of an endless restart.
- Memory
The kernel makes a list of the free memory and hands it out to programs.
- Many tasks at once
A clock ticks 1000 times per second. With every tick the kernel can switch to another task – so many things run at the same time.
- Devices
The kernel finds the devices: USB, hard disks, network card, sound card. Each one gets its driver – a small program that knows how to talk to it.
- Desktop
The desktop starts: windows, taskbar and start menu are drawn by AstraOS itself.
Many tasks, several cores
Every task gets a very short turn (10 milliseconds), then the next one comes. If one program hangs, the rest of the system keeps running.
Modern processors have several cores – small processors inside the processor. AstraOS uses all of them: each core works on its own tasks. In the Task Manager you can see which task runs on which core.
Memory
Every program gets its own memory area. It cannot see or change the memory of another program. When a program ends, AstraOS takes all its memory back. We test this again and again: after starting and stopping many programs, the free memory must be exactly the same as before.
Devices
- USB – keyboards, mice, USB sticks and hubs, also plugged in while running
- Hard disks – reading and writing files
- Network – internet connection with our own network software, and a simple web browser
- Sound – start-up sound and volume control
- Screen, mouse and keyboard – a smooth desktop and real mouse pointers
Not there yet: Wi-Fi, secure websites (https), 3D graphics and many kinds of network cards. Speed on real PCs is not measured yet.
Programs from other systems
Linux programs
AstraOS understands the format of Linux programs. Simple Linux programs that run in a text window already start – including the BusyBox toolbox with its terminal.
Windows programs
AstraOS has its own loader for Windows programs (.exe) – without any Windows code. Simple Windows programs that run in a text window start. Programs with their own windows do not work yet.
AstraOS apps (.aapp)
Our own app format. An app contains the program, the rights it wants and a digital seal. Apps can open their own windows on the desktop. More on the security page.
How we test
For every part there is an automatic test. It starts AstraOS in a virtual computer, clicks and types like a person, takes pictures of the screen and checks the result – for example: starting with only 64 MB of memory, USB, network, sound, disks, programs, windows, the web browser and the protection. That is why we can say what works – and also what does not.
What comes next
- AstraOS on ARM computers (for the alpha)
- Starting on real PCs; installing with Astra Install Helper (beta)
- Windows programs with their own windows
- Secure websites (https) in the browser
- More protection – see the security page