[Coco] Trying to understand Cart Usage on Coco3

[Robert Gault]

Duhh, my mind must be going. :)

On a Coco3 you must force ROM mode before attempting to read the external ROM. 
So, first POKE&HFFDE,0 and then try to read the Typing cart; ?PEEK(&HC000).

RETRO Innovations wrote:> On 8/23/2015 2:31 PM, Robert Gault wrote:
>> RETRO Innovations wrote:
>>> I am working on a small project that puts some EPROM in the cart port. I am
>>> trying to test that the EPROM is in the right place, but I don't know how to
>>> test via the Coco3 BASIC that the EPROM is there.  I've disconnected the CART
>>> pin from Q on a std Typing Tutor Cart to so some testing, but I am not sure
>>> where the addresses should be.
>>>
>>> Any help would be appreciated.
>>>
>>> Jim
>>>
>>
>> Is the Cart plugged into the Coco3 cart port or an MPI?
>>
>> All Tandy Cart/Paks will have their ROMs addressed at $C000; same as the Disk
>> ROM. Your device will now not auto-start and you should be seeing the Extended
>> Basic message at turn on.
>> To access the EPROM, assuming there is a program which starts at $0000 in the
>> EPROM, just enter EXEC&HC000. Alternatively, you may be able to get the EPROM
>> to auto-start without using the CART line by having the bytes in the EPROM at
>> $0-1 = DK with the program start located at $0002.
> Yeah, I don't want to *run* the code at that address, I just want to check that
> my code shows up in those addresses.
>
> I pulled the CART/Q jumper so the autostart cart would not start on boot.  I
> then did a ?peek (49152), and I got 207, but the first byte of Typing Tutor is
> 204, and the number I get from peek (49152) is not consistent across boots.
>
> Jim
>
>