[Color Computer] Re: [Coco] Hidden 256-color mode

[jdaggett at gate.net]

Mike

In a large enough  FPGA you can do the whole Coco 3. 

Presently I can use John Kent's 6809 CPU. It takes up 2/3rds of a 
Spartan 2e 300K gate part. The GIME is about 70% coded in VHDL. 
Not sure but I believe that I can keep it well under 50K equivalent 
gate count. That  leaves about 50K equivalent gate count for the 
PIAs and the salt chip. 

Ram would be external. Thinking of using 512K srams at 20nS 
access time. Four chips for a toal of 2Megs. John Kent's CPU runs 
at 12.5 MHz. The initial timing data that I am seeing with the early 
synthesis is that all logic sections operate at 50MHz or above on the 
GIME chip section. That may reduce a bit due to routing issues 
when the design is fitted into the FPGA.

If everything goes as hoped, I should have the GIME section coded 
by the end of August and start testing it for the next several months. 

james

On 10 Aug 2005 at 9:35, Mike Pepe wrote:

To:             	ColorComputer at yahoogroups.com
From:           	Mike Pepe <lamune at doki-doki.net>
Date sent:      	Wed, 10 Aug 2005 09:35:49 -0400
Subject:        	Re: [Color Computer] Re: [Coco] Hidden 256-
color mode
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> Now, if we were to make a new GIME in VHDL and a big FPGA, we could
> always put it back in!