[Coco] 32K carts?

[jdaggett at gate.net]

Joe

per the service manual IC2 is: 

uPD27C256D-20 or uPD23C256EC


james


On 23 Oct 2007 at 12:35, Joe wrote:

> Any first hand info on 32K carts? I would assume they are the same but
> you know what happens when you ass u me! Worst case is I'll have to
> trace the pins and make sure they go to where I think they should.
> 
> ----- Original Message ----- 
> From: <jdaggett at gate.net>
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Sent: Tuesday, October 23, 2007 11:48 AM Subject: Re: [Coco] 32K
> carts?
> 
> 
> > 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!"
> >> >
> >> > --
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> >>
> >>
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