[Coco] Homebrew CoCo Games

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Or maybe add just one chip, shiftregister, then you need only 2 lines from the Cpld to address the 8 bit.


cb

On 12/12/2015 12:19:27 AM, RETRO Innovations <go4retro at go4retro.com> wrote:
On 12/11/2015 11:20 PM, Nick Marentes wrote:
> On 12/12/2015 2:22 PM, RETRO Innovations wrote:
>> On 12/11/2015 7:54 PM, Mathieu Chouinard wrote:
>>> Why am I dreaming of a "super" cocosdc with the AY(3)8910 in it ...
>> Just synthesized a 512kB FLASH cart with a smaller cpld on it. 8 IO
>> pins left...
>>
>> But, egad, what a nasty IO integration on that 38910. multiplexed
>> address/data bus. That takes at least 10 pins. Sigh. I might be able
>> to free 2 more up, if I ditch the LED and the second switch.
>>
>> Is there a Coco hookup diagram for that IC somewhere, or some 8-bitter
>> schematic?
>>
>> JIm
>
>
> I was thinking more of a SN76489 which is essentially a smaller
> version of the GI chip minus the I/O.
That chip syncs with the bus so slowly, it's not much better. 500kHz is
the max you can store data into it, so you need to create a suitable
clock from the Coco Clock, and then hold your values for 32 cycles...

If you've got to go through teh trouble, it seems like the AY is a
better idea.

Jim


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