HelenOS sources

DP_MAR7           329 uspace/drv/nic/ne2k/dp8390.c 	pio_write_8(ne2k->port + DP_MAR7, 0);
DP_MAR7           667 uspace/drv/nic/ne2k/dp8390.c 	pio_write_8(ne2k->port + DP_MAR7, (uint8_t) (hash >> 56));
HelenOS homepage, sources at GitHub