The Xt Operating System
XtOS is an operating system written in C and Assembly.
- CPU: Intel i386
- RAM: 2MB
- GPU: Any VGA Card
- HDD: 3½ floppy drive or IDE hard disk with at least 300KB free space
- I/O: IBM PC compatible I/O
This is the system that XtOS is developed on so it should work fine with XtOS. - CPU: VIA Eden @ 500Mhz - RAM: 512MB DDR2 - Chipset: VIA VX800 - I/O: VIA VT1211 Super I/O - GPU: VIAChrome9 HC3 - HDD: 128MB IDE Flash Module - BootOS: FreeDOS 1.2
On Real Hardware
- Download xtos.img.
xtos.imgto a blank 1.44MB 3½ floppy disk using one of the following tools:
- Windows: DiskWrite
- Insert the floppy disk into a computer and boot.
XtOS is developed using NASM and OpenWatcom on a HP t5145 running FreeDOS 1.2.
Code is edited using UW Pico.
STAGE2.BIN is provided by the Watcom Debugger. No debugger is available for
Stage 0: FreeDOS
XtOS Boots from FreeDOS, a open source clone of DOS. The FreeDOS kernel is loaded into HIGH memory to leave space for Stage 2.
Stage 1: LOADER.COM
LOADER.COM is the loader for both
It uses INT 21h services to read both files into memory.
STAGE2.BIN is loaded somewhere in the first 64K of memory.
KERNEL.386 is loaded at
0x30000. After both files are loaded successfully,
LOADER.COM jumps to
Stage 2: STAGE2.BIN
STAGE2.BIN disables interrupts, loads the initial GDT, switches to protected mode, and jumps to
KERNEL.386 in under 100 bytes.
Stage 3: KERNEL.386
KERNEL.386 is the XtOS protected mode kernel. On startup, it loads its own GDT, IDT, and enables interrupts.