有关UNIX安装的问题!

[小侠]

我的IDE硬盘接的是Primary Master(主线主盘)，IDE CDROM接的是Slave Master副线主盘，安装SCO UNIX5.0.6时。在选择安装介质时,在选择:IDE COntroller为Slave(只能选这项) ; Master or Slave为Master(只能选这项), 在输入licence number和code后，继续回车后提示ERROR说No root disk has been detected Can not Proceed,Verify that your hardware configurtion has a disk attached and configured as the primary disk，请问高手这是怎么回事呀，我该如何操作.