ACBST_NEGACK
if (status & ACBST_NEGACK) {
outb(ACBST_STASTR | ACBST_NEGACK, ACBST);
if ((status & (ACBST_SDAST|ACBST_BER|ACBST_NEGACK)) != 0) {
outb(ACBST_BER | ACBST_NEGACK | ACBST_STASTR, ACBST);