SN54LS240-SP SN54LS245-SP SN54LS26-SP SN54LS283-SP SN54LS20 SN54LS21 SN54LS221 SN54LS240 SN54LS241 SN54LS242 SN54LS243 SN54LS244 SN54LS244-SP SN54LS245 SN54LS251 SN54LS253 SN54LS257B SN54LS258B SN54LS26 SN54LS266 SN54LS27 SN54LS273 SN54LS273-SP SN54LS279A SN54LS280 SN54LS283 SN54LS295B SN54LS298 SN54LS299