Re: TI-H: direct bus access

To: ti-hardware@lists.ticalc.org
Subject: Re: TI-H: direct bus access
From: Christopher Lambert <clambert@sparcy.geneva.edu>
Date: Tue, 20 Jan 1998 01:55:34 -0500 (EST)
In-Reply-To: <v02110100b0e9dfb6d62d@[206.149.127.65]>
Reply-To: ti-hardware@lists.ticalc.org



UUUMMMMM, you ahve hit a limitation.  The only space we currently have 
available is the 2MB space where an external ROM would go.  I have not 
been able to access anything above 0x400000.  I don't think the higest 
two or three (I can't remember off hand) addressing pins even exist on 
the CPU.  If they do, they have not been found yet.

Chris Lambert
clambert@geneva.edu
calan@hotmail.com
URL: www.geocities.com/siliconvalley/peaks/6869

On Mon, 19 Jan 1998, Grant Stockly wrote:

> 
> The 68000 can directly access 16MB ram so editing rom to reflect the new
> ram length, add a few resistors, and throw it back in the case.
> 
> >An ASM program be used instead to use it like storage only memory. It
> >would be the cheaper expander method. The ROM deal would be the more
> >complex version, but I have a thought.
> >
> >Is it possible to plant ASM in a backup to replace address ranges and
> >trick the calc into reading RAM instead of ROM. Then add the new "ROM"
> >code into the RAM and direct it to jump from the end of the existing
> >memory and to the added memory. I realize it's probably hell to create
> >suce a program, maybe impossible, but is it possible, and if it is, is
> >it worth a try? If it were possible, you could have contiguous memory
> >expansion with only a customized backup. It could be placed on the fargo
> >backup and transfered. The altered RAM could possibly do the job.
> >
> >Is this possible???!!!???!!!???
> >
> >Richard Piotter
> >richfiles1@hotmail.com
> >
> >>
> >>
> >>Thats the best thing in the world!  Now it is possible directly expand
> >the
> >>memory to 16MB!  (with an edited rom)
> >>
> >>Grant
> >>
> >>>Would anyone care if I told you that I have achieved direct bus access
> >to
> >>>a TI 92?  This has enabeled me to create external memory-mapped I/O
> >>>ports.  Is this a good thing or does anyone even care?
> >>>
> >>>Chris Lambert
> >>>clambert@geneva.edu
> >>>calan@hotmail.com
> >>>URL: www.geocities.com/siliconvalley/peaks/6869
> >>
> >>---
> >>Grant Stockly
> >>AppleCyber - http://www.alaska.net/~gussie
> >>
> >>
> >>
> >
> >
> >______________________________________________________
> >Get Your Private, Free Email at http://www.hotmail.com
> 
> ---
> Grant Stockly
> AppleCyber - http://www.alaska.net/~gussie
> 
> 
>

References:

Re: TI-H: direct bus access

From: gussie@alaska.net (Grant Stockly)