The dip-switches at front panel is used as preset for PROM monitor and kernel. You can see switches, button, volume, led and audio juck inside of LUNA's front panel as following. +------------------------------------------------------------+ +---+ | +--------+ +--------+ +---+ +-+-+-+-+-+ +---+ +---+ /--\ | |BTN| | |DIP-SW 1| |DIP-SW 2| |LCD| | 5 LEDs | |BTN| |VOL| | | | +---+ | +--------+ +--------+ +---+ +-+-+-+-+-+ +---+ +---+ \--/ | +------------------------------------------------------------+ RESET HALT (unused) DIP-SW 1 is used as PROM monitor preset. 1 2 3 4 5 6 7 8 off +---------------+ | | | | | | | | | on +---------------+ bit 1: how to boot PROM monitor off: auto boot on: manual boot bit 2: console device off: bitmap display on: serial line NOTE: It should be on currently. bit 5: boot binary format off: COFF on: BSD a.out NOTE: It should be on always. bit 3,4,6,7,8: PROM internal used NOTE: It should be off currently. DIP-SW 2 is used as value of "howto" variable on this implementation. 1 2 3 4 5 6 7 8 off +---------------+ | | | | | | | | | on +---------------+ | | | | | | | | | | | | | | | +------ RB_ASKNAME | | | | | | +-------- RB_SINGLE | | | | | +---------- RB_NOSYNC | | | | +------------ RB_HALT | | | +-------------- RB_INITNAME | | +---------------- RB_DFLTROOT | +------------------ RB_KDB +-------------------- RB_RDONLY This preset value is saved D7 register by boot program, when kernel booting.