TST - Test for Negative or Zero ;flags(N,Z)
TST opr ;(opr) - $00 ;(DIR) 8 bit direct
TST ,X ;(X) - $00 ;(IX) indexed no offset
TST opr,X ;(opr+X) - $00 ;(IX1) indexed w/8 bit offset
Sets the condition codes N and Z according to the contents of M. The contents
of M(opr) are not altered.