DOS 6.22 UNDELETE causes int-16 unhandled function 0xff

[eyalabraham]

12/16/2013,
DOS 6.22 UNDELETE command causes int-16 unhandled function 0xff with BIOS build: 2013-12-16 22:49:19
Need to add register printing to "Unhandled function" and check function parameters.

12/22/2013,
UNDELETE produces the following call parameters for INT16

=== int-16 unhandled function 0xff
ax=0xffa3 bx=0x0040 cx=0x0000 dx=0x1ac6
si=0x2c2e di=0x0081 es=0x0ee6 ds=0x0040 bp=0x0000

=== int-16 unhandled function 0xff
ax=0xffa3 bx=0x0040 cx=0x0000 dx=0xffa3
si=0x2c2e di=0x0081 es=0x0ee6 ds=0x0040 bp=0x0000

12/23/2013,
added code to return a failed status from INT16/ffh. tested and committed in v1.3