Mitsubishi Electric LS Pro Hardware Technical Reference page 107

Memory and I/O Usage
Bits 4, 5
Bit 6
Bit 7
Write cycles
7 6 5 4
Bit 0
Bits 1-7
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These two bits indicate the presence or absence of a Token-Ring
daughterboard as shown in the following table
5
0
0
1
1
This bit indicates the revision level of the system board. Revision C
boards return a 0, revision D boards return a 1.
This bit indicates the speed of the processor fitted to the system board.
Returns a 1 when a 33MHz processor is fitted. A 0 indicates a 25MHz
processor.
3 2 1 0
596reset
reserved
This bit is used to reset the 82596 Ethernet coprocessor. To reset the
82596 the following sequence must be followed:
write a 0 to bit 0 of 310h
write to port 08Eh
write a 1 to bit 0 of 310h
write to port 08Eh
write a 0 to bit 0 of 310h
write to port 08Eh
Reserved.
4 Significance
0 Token-ring fitted
1 reserved
0 reserved
1 No Token-Ring