WDSD_IBM
CHP_WRITE_REG(chp, wdr_sdh, WDSD_IBM | (drive << 4) | head);
CHP_WRITE_REG(chp, wdr_sdh, WDSD_IBM | (drive << 4));
CHP_WRITE_REG(chp, wdr_sdh, (drive << 4) | WDSD_IBM);
if (st0 == 0xff || st0 == WDSD_IBM)
if (st1 == 0xff || st1 == (WDSD_IBM | 0x10))
CHP_WRITE_REG(chp, wdr_sdh, WDSD_IBM | (0 << 4));
wdr_sdh & _WDC_REGMASK, WDSD_IBM | (0 << 4));
WDSD_IBM);
CHP_WRITE_REG(chp, wdr_sdh, WDSD_IBM | (0 << 4));
wdr_sdh & _WDC_REGMASK, WDSD_IBM | (0 << 4));