[Coco] 32K carts?

[jdaggett at gate.net]

The internal ROM in the Coco 3 is a 27256. 

james

On 23 Oct 2007 at 10:48, Joe wrote:

> That is interesting. I wonder now if all the 32K images floating
> around the net are backward like that. When I was working on getting
> these running I jut assumed the images were correct and my MMU
> emulation was off. now I'm not sure. I've got a real Rampage! cart.
> Does anyone know if the chip inside it is pin compatible with a 27256.
> I'll try to pry it out and read it on an external Eprom programmer.
> 
> 
> ----- Original Message ----- 
> From: "Mark McDougall" <msmcdoug at iinet.net.au>
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Sent: Tuesday, October 23, 2007 5:37 AM Subject: Re: [Coco] 32K carts?
> 
> 
> > Joe wrote:
> >
> >> When you switch to 32K External it gets wierd.
> >> $C001 to Whatever is mapped to the first 16K of the ROM and $8000
> >> to $C000 maps to the last 16K of the ROM. This makes sense as any
> >> code running from rom say at $C??? would need to turn on 32K
> >> External mode, but when that happens if it was a liner map the code
> >> that was executing would "jump up" 16K.
> >
> > Thanks Joe - that's done the trick. I had to swap the upper and
> > lower 16KB in Arkanoid and it runs now! Presumably Rampage has the
> > same issue.
> >
> > I need to order a couple of more passives now to be able to test the
> > flash option and the "Flash2" cart.
> >
> > For those few interested, I'll do some pricing very soon. I've been
> > ultra-busy the last few weeks and have only been able to devote the
> > odd minute here-or-there to this project...
> >
> > Regards,
> >
> > -- 
> > |              Mark McDougall                | "Electrical Engineers
> > do it |  <http://members.iinet.net.au/~msmcdoug>   |   with less
> > resistance!"
> >
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > http://five.pairlist.net/mailman/listinfo/coco 
> 
> 
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