OpenNabu IPL is a replacement firmware for the Nabu Personal Computer. It's a little flaky, which is why it's not called version 1.0 yet. By default, it will attempt to bootstrap from a floppy disk (if it finds one), a hard disk (if it finds one) and a cable modem (if it finds one). You can override this by pressing <Esc> early in the boot process. If it is rebooted, it will try to reload from the last known device - but this also can be overridden with <Esc>. The assembler used to roll it is the "z80asm" in the Debian repos.