Option Rom Page; Token-Ring Daughterboard - Mitsubishi Electric LS Pro Hardware Technical Reference

Memory and I/O Usage
1.6 Mbyte floppy Only bit 0 of this port is used.
When it is set low (default) it indicates that a 2 Mbyte floppy drive is fitted. When it
is set high it indicates that a 1.6 Mbyte floppy drive is fitted (Japanese market only).
Note
The function of this port is different on Rev C system boards. Refer to Appendix B for further
information.
Option ROM These two registers are used to select a 16K page within the 64K option ROM which
page has a base address of 0C0000h.
Only bit 0 is used in each of these ports. The following table shows the start address
of the page selected for each combination of bit 0 of ports 0123h and 0124h.
0124h
Token-ring
7 6 5 4
daughterboard
Bit 0
Bit 1
Bit 2
5/12 LS PRO HARDWARE TECHNICAL REFERENCE
0123h
0 0
0 1
1 0
1 1
3 2 1 0
reset
4Mbps
bus width
size
AIP page
reserved
This bit is used to reset the Token-Ring daughterboard. The values
written to bits 1 to 4 become active only after a reset. A reset casuses
all data and register settings to be lost. The steps necessary to reset the
daughterboard and change the settings controlled by bits 1 to 4 are:
write the required value to 0128h with bit 0 set to 0
write the required value to 0128h with bit 0 set to 1
wait at least 15µs
write the required value to 0128h with bit 0 set to 0
This bit selects between 4 and 16Mbps operation. When set to 0 16Mbps
operation is selected, when set to 1 4Mbps is selected.
This bit selects between 8 and 16-bit modes. When set to 0 8-bit
operation is selected, when set to 1 16-bit is selected.
Start address
0000h
4000h
8000h
C000h