[Coco] DE1 arrives :-)

[Joel Ewy]

On 06/24/2010 09:14 PM, Stephen Adolph wrote:
> I agree with you FPGAs are flexible, that is the point of an FPGA.
> But, there is a lot of extra engineering involved, and also extra
> expense if one needed to make a variety of adapters, for a variety of
> platforms.
>
> It is much cheaper considering all the design and verification to
> standardize on a platform.  But go ahead, retarget the design to
> another FPGA and hardware platform!
>
> Have you ever delivered a real product based on FPGA?  I have!  The
> advice I am giving is from experience.  If someone is willing to do
> all the work to bring up one platform and emulate a coco, ..... we
> should not be looking to repeat all that effort.
>
> So my 2 cents is - buy a DE1...it has momentum!
>
>    

Don't forget, the DE1 is already the SECOND platform for CoCo3FPGA.  It 
was first implemented on the Digilent Spartan-3, which, I might add, has 
more memory and would fit quite easily in a vacated CoCo 2 or 3 case.  :)

I think we should expect that FPGA development boards will come and go.  
If we want our engineering efforts to last, we need to design a modular 
bus for FPGA CoCo hardware interfaces, so you can build a CoCo analog 
audio out board, or a joystick interface, or multipak / cartridge 
connector, and plug those into an appropriate adapter that interfaces 
them with a specific FPGA board, whether that be a development kit or a 
specially-designed CoCo FPGA.

Just that little bit of foresight would modularize the project and make 
it much more flexible for future development.  The CoCo hardware 
interface modules could possibly even be interfaced with a PC for use 
with emulators.  The effort needs to go into a standardized, modular 
interface.  The effort needs to go into a standardized, modular 
interface.  The effort needs to go into a standardized, modular 
interface.  Let's make this our mantra.  The CoCo world is too small to 
afford further fragmentation and duplication of effort.  That's what 
happened in the "CoCo 4" era, and we can't afford to make that mistake 
again.

What bus signals would need to be present for a standardized, modular 
interface?  What kind of connectors should be used?  Header pins are 
hobbyist friendly.  What kinds of additional circuitry are likely to be 
required?  I've already mentioned Audio out (could be Orchestra 90 
compatible), joystick interfaces, and cartridge connector.  What about 
cassette, and bit banger?  Would it make sense to put all that on a 
single board, or split it up?

JCE

> cheers, Steve
>
>
>
>
>
> On Thu, Jun 24, 2010 at 9:02 PM, Aaron Wolfe<aawolfe at gmail.com>  wrote:
>    
>> On Thu, Jun 24, 2010 at 8:44 PM, Stephen Adolph<twospruces at gmail.com>  wrote:
>>      
>>> power pins and ground pins are not flexible!
>>>
>>>        
>> my point is that connecting X hardware to Y fpga board should not be
>> difficult given that there are dozens of I/O pins on the FPGA boards
>> and they are able to be used in a flexible manner from the programming
>> side of things.   any fpga board should be able to communicate with
>> any add on board given a physical adapter to connect the two and the
>> correct programming.
>>
>>      
>>> On Thu, Jun 24, 2010 at 6:51 PM, Aaron Wolfe<aawolfe at gmail.com>  wrote:
>>>        
>>>> On Thu, Jun 24, 2010 at 5:40 PM, Stephen Adolph<twospruces at gmail.com>  wrote:
>>>>          
>>>>> a couple of comments on this DE1 activity-
>>>>>
>>>>> 1)  Get your board before they discontinue...since for this to be
>>>>> interesting, one might want to make expansion cards etc too, and we
>>>>> have a defacto pinout.  They will make a new development board for the
>>>>> next generation parts at some point.
>>>>>
>>>>>            
>>>> The I/O pins are pretty flexible on all the FPGA boards I've seen.  I
>>>> guess it would be wise to design any add on boards to use an adapter
>>>> for connecting to the board, this way additional boards could be
>>>> supported easily.  I don't imagine this will be a problem.
>>>>
>>>>          
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