Any HP80-seires experts around?

[Tony Duell]

Are there any HP80 seires experts here? I've got a curious quesiton.

I am looking at the HP82909 128K RAM module (for the HP86/87 series). 
There are several places on the PCB that are not used -- from memory, 
thre are 4 locations for 14 pin ICs. More curiously, there's a place for 
a rssistor and transsitor to drive the ROMDIS/ line on the computer 
connector.

I am pretty sure the 'missing' chips are simple logic functions. One is 
very probably a '74. Another may well be a '30. But I haven't worked out 
the details yet.

My guess is that some HP product actually used this extra logic. So my 
'curious quesiton' is : What product was it? 

-tony