[Coco] 32K carts?

[jdaggett at gate.net]

Joe

As far as I can remember Motorola never made a ROM/EPROM at the size 
of 256K bits. By the 1987 time frame the Motorola pinout for EPROMs was 
essentially obsolete.  By then I seem to remember that Motorola was 
second sourcing the 27C xxx series of EPROMs.


james


On 23 Oct 2007 at 12:56, Joe wrote:

> 32K full external CARTRIDGES not the internal rom.
> BTW thats not the number on the Rampage rom.
> As a matter of fact I've googled every number on the cart rom with no
> results.
> 
> ----- Original Message ----- 
> From: <jdaggett at gate.net>
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Sent: Tuesday, October 23, 2007 12:44 PM Subject: Re: [Coco] 32K
> carts?
> 
> 
> > 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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