Intel 82555 - Manual (Page 11)

Datasheet 7
Networking Silicon — 82555
3.0 Pin Definitions
All active digital pins are defined to have transistor-to-transistor logic voltage levels except the X1
and X2 crystal signals. The transmit differential and receive differential pins are specified as analog
outputs and inputs, respectively.
The figure below show the pin locations on the 82555 component. The following subsections
describe the pin functions.
Figure 5. 82555 Pin Numbers and Labels