On cold reset Windows CE handheld machines attempt to boot the Windows CE operating system from the boot ROM. The boot ROM is usually not rewritable, so you cannot erase or damage Windows CE image.
You can't boot
NetBSD directly, skipping Windows CE. The
NetBSD bootloader,
hpcboot(8), is provided as a Windows CE application program instead. Though the bootloader is an application program, it blows the entire running Windows CE, its data, and its settings away from RAM (but not ROM!) when the kernel boots successfully. If
NetBSD is halted the machine will go through the cold reset and will reboot into Windows CE.