Subject: Re: Utility chip sio's on 4xx (more stories)
To: Michael Smith <email@example.com>
From: Jason Thorpe <firstname.lastname@example.org>
Date: 03/20/1997 19:47:00
On Fri, 21 Mar 1997 14:03:46 +1030 (CST)
Michael Smith <email@example.com> wrote:
> It may also control interrupts from the ISA port, but the high 4 bits
> in the byte at 0xe0 are definitely the interrupt enable bits for the
> Frodo onboard UARTs. It wouldn't actually surprise me all that much
> if all of the IRQ lines on the ISA slot were tied together, so you'd
> only need one interrupt input somewhere.
...as far as I know, that is how it works... the sio's are probably
at the top 4 IRQs.
> Hmm, on the 425 it's at scode 12; still, that implies that it's in
> "real" dio space, and should behave like a normal DIO device. Any
> docco for that?
...not that I can find. As far as I know, it was never documented publicly.
> There are some other issues here that may seriously affect the
> performance of such a driver though; the indirection necessary to
> handle both I/O mapped and memory mapped registers, as well as the
> different spacing (the dca in the 300's is spaced on alternate bytes,
> in the 700 they're packed, and the apci ports appear to be spaced one
> byte per longword) will be expensive, which may be significant on
> slower systems.
...it's all memory-mapped on the hp300. We've already dealt with these
issues... it's called "bus.h" :-)
> I wouldn't bother with the mouse as a seperate device; the data from the
> mouse is part of the keyboard data stream; use the same major and a
> different minor to select between the two.
..this is the model attaches the mouse as a logical child of the keyboard.
It's mainly a place where "mouse" events are collected (for the benefit
of an X server).
> > (BTW, any locals want to help me replace the LANCE on this 425? Dave?
> > I'll buy the first round... :-)
> Hmm, if you were local I'd say bring it on over and do it here, but
> until/unless someone headhunts me that's going to be tough. 8(
...wow, more reasons to visit Australia! :-) (Off topic, but are you
Jason R. Thorpe firstname.lastname@example.org
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