U18 is the only chip that changed between SP1 and SL1.  U15 and U14
are the same in both releases.

U18 -- SP-1 [C50A]

U18 -- SL-1 [B30A]
U15 -- SL-1 [780A]
U14 -- SL-1 [2C24]

U6  -- L-4  [4D04]
U6  -- L-3  [5103]
U6  -- L-1  [2301]
U6  -- P-17 [9AE7]

