Hi!
You can use the 40GB 2.5" hard disk with a Kickstart 3.1 equipped A1200. So if you have Kickstart 3.0, you will have to upgrade to
3.1 ROMs unless you install the IDEFIX package.
The best solution is to have Workbench 3.5 or 3.9 with the drive as large drive sizes will be properly reported and it has the updated FastFileSystem/NSDPatch. However, if you are running 3.1, then we will put SmartFileSystem on it and the necessary patches. However their will still be partition size reporting errors with 3.1.
With the patches, you can use the drive with large partitions.