HelenOS sources

DP_BNRY           301 uspace/drv/nic/ne2k/dp8390.c 	pio_write_8(ne2k->port + DP_BNRY, ne2k->start_page);
DP_BNRY           484 uspace/drv/nic/ne2k/dp8390.c 		uint8_t boundary = pio_read_8(ne2k->port + DP_BNRY) + 1;
DP_BNRY           550 uspace/drv/nic/ne2k/dp8390.c 		pio_write_8(ne2k->port + DP_BNRY, next);
HelenOS homepage, sources at GitHub