SBCD - M68K instruction reference

sbcdSubtract decimal with extend 
Subtracts two packed binary-coded-decimal bytes together with the extend flag.
Size .b
XNZVC ●–●–●
● set from the result
– not changed
Reads X
Forms  sbcd ,   
 sbcd ,   
Operands Dn A data register, d0 to d7. More
-(An) The simulator first decreases the address register by the operation’s size in bytes, then accesses memory at the new address, for example -(sp). More