Moreover, how would you even access it in software without burning a custom ROM? Unless it's just duplicating all printed output, in which case it's clearly one-way.
To quote Katie's article "
Enhance your HP-97 -- Add a Clock and More":
The HP-97 and HP-97S are identical except for the addition of the I/O pod on the 97S. This project demonstrates how it is possible to achieve some of the functionality of the 97S (including the pod) on a plain HP-97. In particular, it demonstrates how input can be feed to a 97 in the same way that the 97S pod does, only more so....
This is not a 97S as the 97S has an umbilical cable extending out the rear.
The KW mod has an internal circuit added with no external connector.
Perhaps the winner of this auction (or the seller) could share pics of the internals of this machine.
TomC