I just tried that, Dave, and it changed as you said. Only trouble is the coimputer wouldn't start except in safe mode - in safe mode there was now an icon in Systems/Device Manager for Hard drives - with Generic IDE Type 46 twice, Generic IDE Drive 47 and Genereic IDE 80.

Anyway I removed one of the 46s and tried again. It still wouldn't reboot except in safe mode, so I went back into BIOS and undid the change back to User and tried again.   Now I've found that the Icon for drives in Device Manager is still there - and it has Generic IDE Type 46 and 80 as well as the floppy. But still no sign of the second drive under My Computer, so I can't access it.

Anyway it feels as if messing around in BIOS is the right way rather than with the hardware - unless I did put the wrong plastic plug in and that is interfering.

Thanks folks. Touch wood we're getting somewhere. And now I've got to go out and do some shopping, so if there are any helpful suggestions it'll be a few hours before I get to see them. The Mudcat is bloody marvellous!