[Coco] CoCo4! 50% done!

[iggybeans at comcast.net]

From: iggybeans at comcast.net 
To: coco at maltedmedia.com 
Sent: Tuesday, February 11, 2014 8:24:03 AM 
Subject: Re: [Coco] CoCo4! 50% done! 



On 11/02/2014 12:15:31 Mark McDougall <msmcdoug at iinet.net.au> 
wrote: 


>FTR, recreating the Coco3 is nowhere near as complex as rewriting the 6809 
>core. So if you want to start somewhere, I'd look at a new Coco3 before 
>attempting a new core. 


>As I mentioned here recently, and it appears to have been all-but-ignored, I 
>am aware of a rather accomplished FPGA designer who has recently been 
>working on a 6808 implementation, and has plans to extend it to 6809/3 at 
>some point. No word on ETA at all unfortunately. 


Yes, a more accurate 6809 core would be a lot of work, a 6309 core would be 
harder, and an enhanced version of the latter would be an enormous 
undertaking. 
But an improved interrupt system (say with a couple of bits for vectoring like the 
68K) would be nice. 
And I wonder what a fully 32 bit 6309 would look like. 


>IMHO the bitmapped graphics of the Coco3 would be perfectly complemented 
>with a simple scrolling tilemap and sprite engine. They're actually rather 
>trivial to implement in an FPGA, but offload a lot of work from the CPU and 
>would enable some pretty cool platform and shooter games! By the same token, 
>adding 2D pixel scrolling to the bitmap wouldn't go astray either! 


Yes, good ideas. 
How about a dedicated sound generator, improved A to D resolution, a better 
MMU and DMA? 
On the Sprite Generator, this is probably the lowest hanging fruit as there are 
implementations of this in FP GA.