I'm about to crash for the night.  *sigh*

Current status is looking promising; with 0x28 in the 
"interrupt vector register", the frodo chip is generating
level 5 interrupts.  Now I have to work out how to acknowledge
them 8)

So far I'm working with this (courtesy of Herb):

        picbase+0x0             upper interrupt enable reg.
        picbase+0x4             lower interrupt enable reg.
        picbase+0x8             upper interrupt pending reg (r/o)
        picbase+0xc             lower interrupt pending reg (r/o)
        picbase+0x10            unused
        picbase+0x14            unused
        picbase+0x18            interrupt vector register
        picbase+0x1c            interrupt ack (?)

I suspect I need to do _something_ with the "interrupt ack"
register.  Any guesses?  I'm trying things like "stuff the
interrupt bit number into it", "read from it", "write to it", 
etc., any other ideas would be good though.

Some other interesting 'features' of the apci ports may make
them less than ideal for a 'generic' 16x50 driver though, eg.
the fact that the IIR appears to read 0x07 on "no interrupt",
not 0x01.

--
Mike Smith  *BSD hack  Unix hardware collector
The question "why are the fundamental laws of nature mathematical"
invites the trivial response "because we define as fundamental those
laws which are mathematical".  Paul Davies, _The_Mind_of_God_