PrismOS

PrismOS is a small hobby operating system that boots via GRUB and runs on x86 hardware (or in QEMU). It provides a simple framebuffer console, a basic shell, and a handful of built-in commands.

Quick build & run

Install the build dependencies (example for Debian/Ubuntu):

sudo apt-get install build-essential nasm gcc-multilib xorriso qemu-system-x86 grub-common grub-pc-bin mtools

Build and run:

make run           # build (if needed) and boot the ISO in QEMU

Other useful targets:

make clean         # remove build artifacts
make run-serial    # boot and mirror COM1 to your terminal
make run-serial-log # boot and save COM1 output to build/serial.log

Notes:

• The build uses 32-bit compilation flags (gcc -m32). Ensure you have multilib support installed.
• make run launches QEMU for quick testing; you can also boot build/os.iso in a BIOS-mode VM.
• make run-serial launches QEMU with debug logs. If you are running bare-metal use serial port.

If you want a reproducible cross-toolchain build, replace the host gcc invocations with an i686-elf cross-compiler and adjust the Makefile accordingly.

Developing and Contributing to PrismOS

Important

All code you commit must be clean and have comments. For development, edit sources under src/, then re-run make run.

Subset C Compiler (prismcc)

PrismOS includes a lightweight subset-C pipeline that targets a bytecode VM inside the OS.

Build the compiler:

make prismcc

Compile a program to a Prism app package:

cat > hello.c <<'EOF'
int main() {
		int a = 2 + 3;
		print("Hello from prismcc");
		print_int(a * 10);
		return 0;
}
EOF

./build/prismcc hello.c hello.app

Copy the generated app to PrismOS disk content (8.3 FAT name recommended), then run in PrismOS shell:

app-run /HELLO.APP

Supported Subset

• One function: int main() { ... }
• Statements:
  • int x = expr;
  • x = expr;
  • print("text");
  • print_int(expr);
  • return expr;
• Expressions: integer literals, variables, + - * /, unary -, parentheses

The compiler emits Prism app containers with a BCVM bytecode payload, and PrismOS runs them through the in-kernel bytecode VM.

Native Compiler Inside PrismOS

PrismOS now includes an in-OS subset C compiler command:

cc <input.c> <output.app>

Example flow from PrismOS shell:

edit /HELLO.C
cc /HELLO.C /HELLO.APP
app-run /HELLO.APP

This uses the same subset language as prismcc and compiles directly on the PrismOS filesystem.