no peek or poke under xenix?

[Peter H. Berens]

We have a device driver for a memory mapped device that crashes the
system when the board is not installed in the system and someone opens
the device node.  We would like to be able to use peek or poke in the
open routine to determine if the memory addresses the board responds
to are present, however xenix does not appear to support any such
functions as peek or poke to carry this out.  Does anyone know how
this should be handled under xenix?  All the example device drivers
do not appear to deal with this problem.

Thanks in advance.