.TH INTRO 1
.SH NAME
    intro - introduction to ZenithOS userspace

.SH DESCRIPTION
    ZenithOS is a hobbyist 64-bit operating system written in C++20.
    Userspace programs run in Ring 3, are loaded as static ELF64
    binaries, and communicate with the kernel through the x86-64
    SYSCALL/SYSRET mechanism.

    Programs are compiled with a freestanding cross-compiler and
    linked at virtual address 0x400000. There is no standard C
    library for C++ programs -- all system interaction goes through
    the zenith:: syscall wrappers.

.SH GETTING STARTED
    To write a new program, create a directory under programs/src/
    with a main.cpp file. The entry point is:

        extern "C" void _start() { ... }

    There is no argc/argv. Include <zenith/syscall.h> for the full
    typed syscall API. Include <zenith/heap.h> for malloc/mfree.

    Build with:

        cd programs && make

    The resulting ELF binary appears in programs/bin/.

.SH SHELL
    The built-in shell is the primary way to interact with ZenithOS.
    Type 'help' at the shell prompt for a list of commands. Use
    'man shell' for detailed shell documentation.

.SH MAN PAGES
    The following man pages are available:

        intro(1)        This page
        shell(1)        Shell commands reference
        man(1)          The man command itself
        syscalls(2)     Overview of all syscalls
        spawn(2)        Process spawning
        file(2)         File I/O syscalls
        framebuffer(2)  Framebuffer access
        malloc(3)       Memory allocation

.SH SEE ALSO
    shell(1), syscalls(2), malloc(3)