root@zaden:/tmp# fdisk -l

Disk /dev/hda: 20.4 GB, 20490559488 bytes
255 heads, 63 sectors/track, 2491 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1               1          77      618471   82  Linux swap
/dev/hda2              78         123      369495   83  Linux
/dev/hda3             124        1398    10241437+  83  Linux
/dev/hda4   *        1399        2491     8779522+  83  Linux

Disk /dev/hda1: 20.4 GB, 20490559488 bytes
255 heads, 63 sectors/track, 2491 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot      Start         End      Blocks   Id  System
/dev/hda1p1               1          77      618471   82  Linux swap
/dev/hda1p2              78         123      369495   83  Linux
/dev/hda1p3             124        1398    10241437+  83  Linux
/dev/hda1p4   *        1399        2491     8779522+  83  Linux

Disk /dev/hdb: 22.6 GB, 22605004800 bytes
255 heads, 63 sectors/track, 2748 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdb1               1          29      232911   82  Linux swap
/dev/hdb2   *          30        2748    21840367+  83  Linux


Now we use acorn-fdisk and find that /dev/hda contains not Linux 
but RISC OS Filecore partitions:

root@zaden:/tmp# acorn-fdisk -l

Disk /dev/hda: 16 heads, 63 sectors, 39703 cylinders
Units = cylinders of 1008 * 512 bytes

   Device Boot   Begin    Start      End   Blocks     Id   System
/dev/hda1            0        0    39703   20010312    100  Filecore
/dev/hda2        39703    39703    39704          1   fffe  Reserved/Free

Disk /dev/hdb: 16 heads, 63 sectors, 43800 cylinders
Units = cylinders of 1008 * 512 bytes

   Device Boot   Begin    Start      End   Blocks     Id   System
/dev/hdb1            1        1      463     232911     82  Linux Swap
/dev/hdb2           29      463    43797   21840367+    83  Linux Native
root@zaden:/tmp#