[Coco] Reverse video mod

[Joe Grubbs]

Cool! Coincidentally I was going to do this to the machine that will be receiving your "lower kit" :)

--- Original Message ---

From: "Zippster" <zippster278 at gmail.com>
Sent: April 19, 2015 1:19 PM
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Subject: Re: [Coco] Reverse video mod

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


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