identify what chips go in U19 and U15.
I'm pretty sure that the one closest to the ROMS is
the 6809E, but not sure of what the other chip should
be.
If it's a 40 pin chip then you might br able to do it by a process of
elimination!
The 5 40 pin chips in a Dragon or CoCo are 6809E, 6883, 6847, 2 off 6821.
-tony