Figure 2—The Am79C874 is an Ethernet 10/100 PHY device that connects directly to the eZ80F91’s media-independent interface (MII) on one side and an RJ-45 jack (with integrated magnetics and LEDs) on the other. The SN75160 and SN75161 provide some state decoding logic as well as line drivers that are electrically compliant with GPIB. The 5- and 3.3-V power supplies are standard fare.