[Coco] CoCo 3 68000/RAM board project

[jdaggett at gate.net]

All

The CPU module containing the FPGA for the 6809 is laid out and needs verification. The 
memory module is also done. It will be a 1Megabyte by 16 10 nS SRAM. Another board 
could be done using SDRAM. Now the Main board and peripheral boards are left to design 
and lay out. 

What I am doing is shrinking the size of the main Coco board down to 100mm by 80mm 
size. Taking a fes of Sock's ideas also into consideration. The CPU  FPGA will be capable 
of one 6809 plus room left over for a math coprosser or a second 6809.  The GIME FPGA is 
also large enough to handle VGA desktop of 800x600 pixels at 8 bit color. That is able with 
the 2Mbytes of ram. 1Mbyte for video desktop and at least one 640x480 hardware window. 
Lower resolutions can have more windows. 

Coding status for the GIME chip is all the registers are done. Need to do the video section 
with windowing, and the linear address generater for the video ram access. Also the 
multipexor between the CPU and video addresses. 

As for the math coprosser, I have a cordic processor started. It eventually will handle all 
division, multiplication and several trig functions. I have yet to dicide wthether it will be just 
integer or handle floating point yet. That will depend on how much room is left after the core 
of the cordic is left. 

james

 
On 7 May 2009 at 6:50, Frank Swygert wrote:

>  I think the memory issue has
> basically been overcome with the 2MB board, and the other two are
> being worked on -- an FPGA GIME and 6809. Once those are done one
> could make an adapter board and plug each into a CoCo board, but at
> that point it would probably be better to build another board around
> the two FPGAs.