In a nutshell:
The controller will have x channels. The channels are noted by the number of connectors. 2 connectors means two channels and so forth. Each channel can use a total of 2 devices.
From memory (will check my dead QS when I get home) the QS has two channels. One is faster and intended for HDDs, the other is for the Optical Drive and Zip.
If you are using two devices (aka two HDD on one channel or the cd and zip together, etc), they either must both be set to cable select or one on master and the other on slave. For a single drive, it must be set to master or cable select. (Though, I've had some that would boot even with a single drive set as slave, so YMMV.)
The controller will have x channels. The channels are noted by the number of connectors. 2 connectors means two channels and so forth. Each channel can use a total of 2 devices.
From memory (will check my dead QS when I get home) the QS has two channels. One is faster and intended for HDDs, the other is for the Optical Drive and Zip.
If you are using two devices (aka two HDD on one channel or the cd and zip together, etc), they either must both be set to cable select or one on master and the other on slave. For a single drive, it must be set to master or cable select. (Though, I've had some that would boot even with a single drive set as slave, so YMMV.)