HelenOS sources
DP_RBCR0 121 uspace/drv/nic/ne2k/dp8390.c pio_write_8(ne2k->port + DP_RBCR0, esize & 0xff);
DP_RBCR0 146 uspace/drv/nic/ne2k/dp8390.c pio_write_8(ne2k->port + DP_RBCR0, esize_ru & 0xff);
DP_RBCR0 213 uspace/drv/nic/ne2k/dp8390.c pio_write_8(ne2k->port + DP_RBCR0, ETH_ADDR << 1);
DP_RBCR0 231 uspace/drv/nic/ne2k/dp8390.c pio_write_8(ne2k->port + DP_RBCR0, ETH_ADDR << 1);
DP_RBCR0 291 uspace/drv/nic/ne2k/dp8390.c pio_write_8(ne2k->port + DP_RBCR0, 0);
DP_RBCR0 371 uspace/drv/nic/ne2k/dp8390.c pio_write_8(ne2k->port + DP_RBCR0, 0);
DP_RBCR0 501 uspace/drv/nic/ne2k/dp8390.c pio_write_8(ne2k->port + DP_RBCR0, size & 0xff);
HelenOS homepage, sources at GitHub