The M54/74HCT245, HCT640 and HCT643 utilise silicon gate C2MOS technology to achive operating speeds eqivalent to LSTTL devices. Along with the low power dissipation and high noise immunity of standad CMOS integrated circuit, it possesses the capability to drive 15 LSTTL loads. These IC's are intended for two-way asynchronous communication between data buses, and the direction of data trasmission is determined by DIR input. The enable input (G) can be used to disable the device so that the buses are effectively isolated. All input are equipped with protection circuits against static discharge and transient discharge. These integrated circuits have input and output