These octal bus transceivers are designed for asynchronous two-way communication between data buses. These devices transmit data from the A bus to the B bus or from the B bus to the A bus, depending upon the level at the direction-control (DIR) input. The output-enable input disables the device so that the buses are effectively isolated. The -1 versions of the SN74ALS641A and SN74ALS642A are identical to the standard versions, except that the recommended maximum IOL is increased to 48 mA in the -1 versions. The SN74ALS641A, SN74ALS642A, and SN74AS641 are characterized for operation from 0°C to 70°C.