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SMSC LAN91C111 32/16/8-Bit Three-In-One Fast Ethernet Controller
SMSC AN 9.6 37 Revision 1.0 (08-14-08)
APPLICATION NOTE
The Intel 80X86 and Pentium and DEC Alpha RISC processors are Little Endian.
6.2.3 Bi-Endian
As previously stated, some processors have the ability to switch their modes of operation to
accommodate different endian structures. These processors include the DEC Alpha and the PowerPC.
The control of their endian structure is done via software; please refer to the processors documentation
for details regarding use of the bi-endian features of the particular processor you are working with.
6.3 Implications for the LAN91C111
Whether or not design considerations need to be taken regarding the endian issues is an application
specific decision. This section will discuss these issues and give examples of how to connect the
LAN91C111 to a device that requires byte swapping (Big Endian). By better understanding the issue
the design engineer can decide if and how to accommodate the differences in endian structure.
6.4 Physical connections for Big Endian
In a design that requires the processor to LAN91C111 connections to be byte swapped you would
connect the data bus as displayed in the figure below.
Table 6.2 Little Endian Memory Images
Double Word Value to be Stored = 12345678h
BYTE ADDRESS
32 10
DATA VALUES (H)
12 34 56 78
BINARY VALUES
0001 0010 0011 0100 01010110 0111 1000