[Coco] 68/63-09 Piggy Back

[Richard Lorbieski]

I've never been a fan of piggy backing. It can ruin both chips and if either chip fails, then all of them have to be replaced. 

It's a messy situation if one of the chips needs to be replaced.

Just my experience.

-----Original Message-----
From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Tim Fadden
Sent: Tuesday, October 31, 2017 11:41 AM
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Subject: [Coco] 68/63-09 Piggy Back

I was looking for some other info in my coco files and ran across this. 
I remember someone asking about it, so here goes.  I haven't personally tried it, but see no reason it shouldn't work.

You can stack a 6309 on top of your computer's existing 6809. Here's how...

Cut pin 39 (TSC) of the 6809, leaving a small piece sticking out of the processor so you can solder to it.

Take a 40 pin IC socket. Cut off pins 5, 6, 33, 36, and 38. Bend out pin
39 so you can solder to it.

Stack the 40-pin IC socket on top of the 6809. Solder all of the corresponding pins together. DO NOT solder the pins 39 together.

Now you have two options:

1.    Solder a wire from 6809 pin 39 to +5V, and another wire from socket pin 39 to ground.

2.    Solder a 4.7K resistor between each pin 39 and +5V. Then take a SPDT switch, connect the common contact to ground, and connect each end to a separate pin 39.

In either case, finish up by plugging the 6309 into the socket. If you picked option 1, you now have a 6309 system. If you picked option 2, your system is now switchable between the 6809 and the 6309 (before power-up - not while running!).


--
Tim Fadden
"Hey Schmidt, don't forget about the six P's.
Proper Preparation Prevents Piss-Poor Performance!"


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