Re: FPGA/CPLD different approach

From: Gerrit Heitsch <>
Date: Thu, 05 Sep 2013 17:26:34 +0200
Message-ID: <>
On 09/04/2013 11:32 PM, Steve Gray wrote:
> The Atari crowd has a similar thing called the VBXE
> I think we could definitely use a replacement VIC with VGA out and
> perhaps some additional features like the F18A does.
> For TED perhaps we could add sprites like the VIC, or for VIC add the
> extended colours like the TED.

Adding features to such old hardware is quite pointless since almost no 
one will use them.

Also, adding sprites to TED or extended colors to VIC will mean quite a 
bit of redesign, especially in the bus interface pincount. VIC only has 
4 Bits (D8-D11 to the color RAM) for colors and some modes rely on that 
(using the text mode screen buffer for 2 colors per byte in multicolor 
mode). Going to 8 Bits per color (7 plus blink) would mean certain modes 
will no longer work.

On the other hand, TED has no extra data lines for a color RAM, already 
uses 2 badlines and has less free cycles between scanlines so 8 sprites 
might not be possible at all.

It's a nice idea, but once you think about it, it doesn't really make 
sense and would result in an awful lot of extra design work. Getting a 
replacement for VIC and TED that works 100% (even with all the strange 
demo tricks) will already be hard enough.

Most important would be a 100% replacement for the 8501.


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Received on 2013-09-05 16:00:03

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