CAC_GET1
switch (CAC_GET1(dinfo->mirror)) {
_lto4b( CAC_GET2(dinfo->ncylinders) * CAC_GET1(dinfo->nheads) *
CAC_GET1(dinfo->nsectors) - 1, rcd.addr);
CAC_GET1(dinfo->nheads) * CAC_GET1(dinfo->nsectors);
blks = CAC_GET2(dinfo.ncylinders) * CAC_GET1(dinfo.nheads) *
CAC_GET1(dinfo.nsectors);
bv->bv_level = cac_level[CAC_GET1(dinfo.mirror)]; /*XXX limit check */