[comp.sys.ibm.pc] What is Port 00A0

mdvries@cwi.nl (Michiel de Vries) (09/16/89)

I'm working on a (program published in a magazine) that uses port 00A0.
The only reference to this port I can find, is in the port map
in the IBM-PC Technical Ref. manual, and in similar list in some
books.  All these sources call it the 'Nonmaskable interrupt (NMI) mask
register', but none of them elaborate on it. (They do explain the 8259
registers, programmable through ports 20h & 21h). I must have checked
at least a dozen books, including the MS Doss Encyclopedia.

Is there anybody who can enlighten me about this port?  
Any references about it's usage?

Many Thanks!

Michiel de Vries, CWI, Amsterdam, The Netherlands.
mdvries@cwi.nl