[Coco] A Technical Question

[T. Franklin]

Thanks for the input Steve. Yes, the project is ambitious and I'm not sure it can even be done. I was throwing out ideas floating around in the back of my brain. The OpenGL idea came from a post of an FPGA module someone did that supports 3D rendering. My thought was offloading the higher graphic functions to the FPGA to improve CoCo gaming graphics.

It's just a "futzing" around project to give me something to do on boring rainy weekends.

See you Saturday (if you are going to CoCoFest)



-----Original Message-----
From: Steve Bjork [mailto:6809er at srbsoftware.com]
Sent: Thursday, May 17, 2012 12:59 PM
To: 'CoCoList for Color Computer Enthusiasts'
Subject: Re: [Coco] A Technical Question

On 5/17/2012 9:02 AM, T. Franklin wrote:> I have atechnical question about the video link and RAM on a computer (not necessarilya CoCo). I'm creating my own 6809 basedcomputer on an FPGA and stuck on a direction as to implementation. It has to dowith the write CPU cycle of the video area. Is it normal to allow the CPU towrite to video RAM only during the refresh& blanking? If so, is it normalto use a dual port RAM scheme or is the processor held in a wait state until thehorizontal scan is complete?While Sega and Nintendo games systems of the time of the CoCo could only write to Video Ram during the V & H blank, the CoCo did not have this limitation.The CoCo's memory was shared equality between between the CPU and the Video system. One RAM cycle is feed to the CPU and the next cycle is read for the Video. Basically, memory is synch-lock between the two systems. This why the CPU speed is based on the video timing. The Dynamic RAM refresh is done during the unused part of the Video RAM access.Knowing how the CoCo works on the basic hardware level is key to the project you are trying to undertake. I would do a lot more study before taking on a project like this this.> Some of theideas I had with this venture is to (like others) implement a CoCoin an FPGA but modify all the graphics routines (i.e. lines, circles, draws andPCLS) to all FPGA core implementation. I?m thinking about adding a 3D FPGA coreimplementation similar to OpenGL for some real cool CoCogaming.Yes, you could FPGA blitter to draw some graphics. But OpenGL 3D graphics? What about the 3D matrix translation and Object texture maps used in OpenGL? How are you going to build anything like that in today's FPGA kits?> This is just mydream but as I slowly get started, I?m finding that questions like this oneplague me for weeks. So any help would be appreciated.>> See you all atCoCoFest!!!>>--Coco mailing listCoco at maltedmedia.comhttp://five.pairlist.net/mailman/listinfo/coco