pub const SCREEN_BASE: u16 = 0x4000
pub const ATTR_BASE: u16 = 0x5800
pub const BORDER_PORT: u8 = 0xFE

pub fn border(color: u8) {
    asm volatile(in color: u8 as reg8, clobber a, clobber flags, clobber ports) {
        "ld a, {color}"
        "out (0FEh), a"
    }
}
