[Coco] Dragon32 with factory Daughterboard SAM chip

[Phill Harvey-Smith]

On 31/10/2013 15:34, Luis Antoniosi (CoCoDemus) wrote:
> What would be the reason for this ?
>
> Its a daughter board with the SAM, some jumpers and 2 TTLs.
>
> Would this be a fix to change the clock rate ?
>
> I have no clues. There is red jumper going to what looks to be the the
> mc6847 Field Synchronization pin.

Yep I have a Dragon 32 like it. The daughter board is Dragon Data 
PN48200, the extra circuit is a 74LS74 and a 74LS32. It appears to 
ensure that the changes to /HS and DA0 happen at co incident with the E 
clock (E is fed to the CLK pin of both flipflops).

I have traced the schematic in Eagle and can post if anyone wants it.

Cheers.

Phill.