Thanks for the reply, I apologize but I do not have much practice with CF. I have verified that by setting as a slave HD the adapter following: http://www.idotpc.com/TheStore/pc/catalog//products/accessories/cfide401big. jpg with a 2GB CF in it on an old PC with Windows 98, it works. I boot properly first the DOS system and I launched FDSIK and then format d: / s on the CF which is formatted in FAT16. On the IBM 5170 Disk I have a controller like this: http://www.amoretro.de/2012/01/winbond-w83757f-ide-controller-und-multi-io-k arte-16-bit-isa.html I ask: 1) do i Simply connect the CF as I have already formatted with win 98? 2) maybe have i to set the adapter as master? 2) i not believe that the ibm 5170 will recognise immediately the CF. I mean have I to a set something in the system firmware or have I to create a most little disk area than 2GB? 3) What should I do exactly? Thanks in advance Enrico