I asked the MC-10 yahoo group what other changes to add if there is sufficient ROM space after ELSE support.  The only requested change so far is for correction of the SIN coefficients.  Microsoft apparently used the wrong values in many (all?) versions of BASIC.

Here are the changes.  The commented out data ontains the original values, and it is followed by the replacement table thanks to Neil.

SINCOF    fcb       6-1                 ; six coefficients in the table

;          fcb       $84,$E6,$1A,$2D,$1B ; -14.38139067 -(2*Pi)^11/11!

;          fcb       $86,$28,$07,$FB,$F8 ;  42.00779712  (2*Pi)^9 / 9!

;          fcb       $87,$99,$68,$89,$01 ; -76.70417026 -(2*Pi)^7 / 7!

;          fcb       $87,$23,$35,$DF,$E1 ;  81.60522369  (2*Pi)^5 / 5!

;          fcb       $86,$A5,$5D,$E7,$28 ; -41.34170210 -(2*Pi)^3 / 3!

;          fcb       $83,$49,$0F,$DA,$A2 ;   6.28318531  (2*Pi)^1 / 1!

fcb $84,$F1,$83,$A7,$EF ; -15.094642578 -(2*Pi)^11/11

fcb $86,$28,$3C,$1A,$44 ;  42.058693944  (2*Pi)^9 / 9

fcb $87,$99,$69,$66,$73 ; -76.705859753 -(2*Pi)^7 / 7

fcb $87,$23,$35,$E3,$3C ;  81.605249276  (2*Pi)^5 / 5

fcb $86,$A5,$5D,$E7,$31 ; -41.341702240 -(2*Pi)^3 / 3

fcb $83,$49,$0F,$DA,$A2 ;   6.283185307  (2*Pi)^1 / 1