The B port operates at BTL-signal levels. The open-collector B ports are specified to sink 100 mA. Two output enables (OEB and OEB) are provided for the B outputs. When OEB is high and OEB is low, the B port is active and reflects the inverse of the data present at the A-input pins. When OEB is low, OEB is high, or VCC is less than 2.1 V, the B port is turned off. The A port operates at TTL-signal levels and has separate input and output pins. The A outputs reflect the inverse of the data at the B port when the A-port output enable (OEA) is high. When OEA is low or when VCC is less than 2.1 V, the A outputs are in the high-impedance state. The pins TMS, TCK, TDI, and TDO are nonfunctional, i.e., not intended for use with the IEEE Std 1149.1 (JTAG) test bus. TMS and TCK are not connected, and TDI is shorted to TDO. BIAS VCC establishes a voltage between 1.62 V and 2.1 V on the BTL outputs when VCC is not connected.