The MC10123 consists of three NOR gates designed for bus driving applications on card or between cards. Output low logic levels are specified with VOL = 2.1 Vdc so that the bus may be terminated to 2.0 Vdc. The gate output, when low, appears as a high impedance to the bus, because the output emitter followers of the MC10123 are "turnedoff." This eliminates discontinuities in the characteristic impedance of the bus. The VOH level is specified when driving a 25ohm load terminated to 2.0 Vdc, the equivalent of a 50ohm bus terminated at both ends. Although 25 ohms is the lowest characteristic impedance that can be driven by the MC10123, higher impedance values may be used with this part. A typical 50ohm bus is shown in Figure 1.