Asus CRW-5232AS User Manual page 28

Master Mode
Cover the two pins labeled MA to set the CRW-5232AS drive
as a secondary master drive. Select this mode if your
computer supports four IDE devices. The computer hard drive
is set as Primary Master.
Slave Mode
Cover the two pins labeled SL to set the CRW-5232AS drive as
a slave device if your computer supports only two IDE devices. If
your computer supports four IDE devices, this mode sets your
CRW-5232AS drive as either Primary or Secondary Slave.
Cable Select Mode
Cover the two pins labeled CS if your computer supports a
Cable Select (CSEL) signal. You need an exclusive interface
cable for this mode. Refer to your computer manual for details.
28 ASUS CRW-5232AS