Mainframe questions

A neighbour came to me with an age old book, which
he needs to mug up in order to clear exams.
But the problem is he wants to understand few things in
it as well.

There are these sentences there in the book : 
"A limitation of mainframe software architectures is that
they do not easily support graphical user interfaces
or access to multiple databases from geographicall
dispersed sites."

I don't know old that description is since I don't know
much about mainframes. I looked up on google for
some time, but could understand these limitations
about graphical user interfaces and why can't a mainframe
access multiple databases?

Ans : 

I  agree with giltjr's comments. Perhaps a short history lesson will shed more light on this...

During the 1980's and 1990's the primary display device was the 3720 family of terminals. There devices were commonly attached to the mainframe channel or via SDLC to a 3270 control unit and the terminals themselves were identified as models 3274, 3278, 3279, etc.  There was one graphic-capable terminal that required the GDDM software to be installed to use it. It was expensive and cumbersome, but it did work. The primary users of this hardware were CAD/CAM, CATIA, and SAS software.

It is common to see 3270 emulator software that communicates with the mainframe via TCP/IP today.
--
The database software was always leading-edge. IBM Invented SQL. Some other original mainframe database system were CICS, IDMS, IMS, Informix, Focus, SAS, and SPSS.