[Coco] Disto 2 Meg kit

[Robert Gault]

Bob Devries wrote:
> Does anyone here have technical knowledge of the Disto 2 Meg kit?
> 
> I want to put one into an Australian Coco3, but there's some differences 
> in the components with respect to the 2 Meg kit.
> 
> 1. The wire that should go to C60 connects to the junction between a 
> resistor and the 28.63636 MHz crystal. The resistor connects to pin 2 of 
> the GIME chip. In the Australian Coco3, that capacitor connects directly 
> to pin 2 of the GIME, and the crystal is 28.475 MHz. The crystel is 
> actually one of those oven type devices in a larger metal case.

The circuit diagram in my service manual has C60 connected to pin 14 on 
the crystal and +5v. Pin 8 of the crystal goes to GIME pin 2. Could be 
the manual is wrong, but if it is right I'd think the wire should go to 
GIME pin 2 not the cap.

Best bet would be to put a scope on pin 2 and see if the Disto wire 
degrades the clock waveform. The only thing that could happen would be 
that the Coco would not work and the scope would indicate a degraded 
master clock signal.

> 
> 2. The other wire connects to HSYNC (pin 40 of IC5), which is the same 
> as the Australian Coco3, but the HSYNC pulse is at a different rate to 
> the US version.
> 

I'd just connect this up and see what happens. Can't do any harm.