Just from memory the cases mentioned:


> So far as I can see, the 6809 lacks instructions that the 6800 has, such as aba, eorb 

`ABA` becomes `PSHS B; ADDA ,S+` - a nifty use of the autoincrement feature :)

`EORB` is still the same on a '09.

> the transfer instructions (tba, tap and the like).

The 6809 uses a unified instruction, 'TFR' so 

 `TBA` becomes `TFR B,A` (1F 98)
 `TAP` becomes `TFR A,CC` (1F 8A)

and so on.