GameOS

Operating system for developing boot sector games & apps

What a heck is it?

GameOS is a 16-bit real mode operating system allowing to run
binary executables in a boot sector (0x0000_7C00 physical RAM address)
It's distributed in a form of 'packs' with bundled games/apps.

GameOS runs on a real hardware

Coding in x86 machine codes under GameOS:

Coding GameOS in x86 assembly (20 videos)

Distribution: GameOS: 3rd party games

• run boot sector games from floppy image

Distribution: GameOS: developer pack

• create new 512 bytes programs in hex editor using x86 machine codes!
• save up to 5 programs onto USB flash drive
• load & edit one of 5 user defined programs
• run user defined games/apps in the boot sector or at 0x0000_0500-0x0000_06FF (hex editor's scope)
• change color scheme
• clear screen

Run in emulator

1. Pick up GameOS.img from the desired pack
2. Command to run in QEMU: qemu-system-i386 -hda GameOS.img
3. Run in online emulator(https://copy.sh/v86/): click upload HDD image then start emulation

Create bootable USB (on linux) & run on real hardware

1. Plug in USB flash drive
2. Run command sudo fdisk -l => /dev/sdb should be your USB flash drive
3. Navigate to where GameOS image is located
4. Run command dd if=GameOS.img of=/dev/sdb count=2880 bs=512
5. Boot from USB flash drive

Useful resources

CHS addresses: https://en.wikipedia.org/wiki/Cylinder-head-sector
x86 Real mode: https://wiki.osdev.org/Real_Mode
x86 Real mode memory segmentation: https://wiki.osdev.org/Segmentation
x86 Memory map: https://wiki.osdev.org/Memory_Map_(x86)
x86 BIOS interrupts: http://www.ablmcc.edu.hk/~scy/CIT/8086_bios_and_dos_interrupts.htm
x86 Assembly registers: https://www.assemblylanguagetuts.com/x86-assembly-registers-explained/
x86 Assembly instructions: https://www.aldeid.com/wiki/X86-assembly/Instructions
x86 Assembler Instruction Set Opcode Table http://sparksandflames.com/files/x86InstructionChart.html x86 Online emulator: https://copy.sh/v86/