What is meant by standard load in digital electronics?

Answer 1

One standard load is the load of a typical input of a specified logic family. This is more relevant with bipolar logic families (e.g. RTL, DTL, TTL, ECL, I2L) than MOS logic families (e.g. NMOS, CMOS). Outputs of devices in these logic families are then rated by the number of standard loads they can drive. However when crossing between logic families (e.g. LS TTL to S TTL) the concept of standard loads is less useful and actual high/low state input current loading and output drive capability calculations should usually be made.