[Coco] Reverse video mod

[Zippster]

Just checked this out.  

Looks like it uses a spare NOR gate on U29 to drive DD6 on the MC6847 high whenever INV is low.

This should be fairly easy to implement in the CPLD code as a dip-switchable mode on my external rom board.

Neat!

- Ed


>> 
>> On 19/04/2015 12:59, Joe Grubbs wrote:
>>> Steve posted pictures of his old CoCo2s, one of which as a Lowerkit and "Reverse video mod", both selectable via chassis mounted toggle switches. The reverse video mod gives green text on a black background.
>>> 
>>> Does anyone know what is being done in hardware to make this happen? Is it separate from the Lowerkit? Steve mentioned there might be a blurb about it in an old issue of Rainbow, but I've not yet found it.
>>> 
>>> Note that this is something I'd like to do on a CoCo2 with the 6847 VDG (NOT the T1 version, which is apparently more configurable with some clever POKES).
>>> 
>>> 
>>>  		 	   		
>>> 
>> 
>> Joe,
>> 
>> That is a simple mod and was described in one of the "Turn of the Screw" 
>> articles.
>> 
>> http://sparksandflames.com/files/FullTurn.pdf
>> 
>> Codimex made this mod a default option on the Codimex CD-6809 machine 
>> here in Brazil.
>> 
>> Daniel