Re: A89: cpu.txt @ http://alh.dhs.org/ti89/

To: assembly-89@lists.ticalc.org
Subject: Re: A89: cpu.txt @ http://alh.dhs.org/ti89/
From: Olle Hedman <oh@hem.passagen.se>
Date: Wed, 14 Jun 2000 09:10:41 +0200
References: <20000613235626.1508.qmail@web1705.mail.yahoo.com>
Reply-To: assembly-89@lists.ticalc.org


It's because the chip in the 89 isn't a pure 68k, but a custom chip with some
extra stuff built into it. port hardware and stuff like that is in the same
chip, but internally it is hooked to the address/data-bus, just like you say.

//Olle

Jeff Flanigan wrote:
> 
> There's something I don't understand about the pinout.
>  I always thought that memory mapped I/O ment that off
> chip hardware (linkport, LCD, battery level detection,
> etc.) responded to different reads/writes over the
> address bus.  I thought they were just hooked up to
> both the data/address busses and had some circuitry
> for interface.  But when I looked at the pinouts, I
> saw that some "memory mapped hardware" was interefaced
> with special pins on the 68k chip (like the linkport
> and batt detection).  Can anyone explain how this
> works to me?
> - Jeff Flanigan
> 
> --- Olle Hedman <oh@hem.passagen.se> wrote:
> >
> > If anyone of you have (and) use cpu.txt with pins
> > added by Johan Borg, that can
> > be downloaded from my page http://alh.dhs.org/ti89/,
> > you should know that there
> > where some errors in it, and it is corrected now,
> > and a new verson is available
> > at the location above.
> > cpu.txt has descriptions of the pins on the custom
> > cpu chip with the 68k in th
> > ti89.
> >
> > //Olle
> >
> 
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References:

Re: A89: cpu.txt @ http://alh.dhs.org/ti89/

From: Jeff Flanigan <propalo@yahoo.com>