[Coco] CoCo2 Strange Side Switches

[Camillus Blockx]

For what I can see, I think it the switches are for Inverse video Green on black and the second one is for upper and real lowercase characters switching. 

If you look closely there is a pin lifted out and I think is Pin 39 (CSS) and is used for switching character mode.

The bottom switch makes the modification undone by switching the pin 39 from MC6874P pin to original PCB hole.

The top switch is connected to the SN74LS273, which is a Flip-Flop with Clear, but I'm not sure if it is connected to pin 20 of it, which would be VCC( 5v) or some other pin. The most likely would be the 5 Volt. I draw that conclusion by the black hose in the middle of the wire, in which I presume is a resistor (pull up).

This is just guessing of the things I can see on the pictures you provide. If you could tell me the exact locations where the modification is done, pin numbers, pins lifted out or cut etc..  then I could give you some better diagnostics.

 Have coco fun ....

Camillus
On 12/3/2014 11:45:26 AM, Bruce W. Calkins <brucewcalkins at charter.net> wrote:
----- Original Message -----
From: "John Goerzen"

> Hi,
>
> So I got a lot of random untested CoCo parts off eBay yesterday. It
> included a CoCo 2 which seems to have been modified or something. On its
> left side are two unlabeled switches:
>
> https://www.dropbox.com/s/avmph8x7oykd222/coco-switches.jpg?dl=0
>
> Anybody seen this before? Any idea what it's about?
>
> Thanks,
>
> John
>
> --
=======================================
Manny, many years ago I set up a CoCo 2B with two less obtrusive slide
switches. One for inverting the boarder video and one for switching the
lower case/inverted letters. That said, to understand what those switches
do, you will need to A: trace the wires, and/or B: try them out.
Bruce W.


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