Special Registers
VL-EPICs-36 Reference Manual
50
Special Control Register
SCR (Read/Write) CA2h (or C92h)
D7
D6
D5
D4
D3
D2
D1
D0
BIOS_JMP
BIOS_OR
BIOS_SEL
Reserved
Reserved
Reserved
Reserved
Reserved
Table 27: Special Control Register Bit Assignments
Bit
Mnemonic
Description
D7
BIOS_JMP
System BIOS Selector Jumper Status
— Indicates the status of the system
BIOS selector jumper at V1[1-2].
0 = Jumper installed – backup system BIOS selected
1 = No jumper installed – primary system BIOS selected
This bit is read-only.
D6
BIOS_OR
BIOS Jumper Override
— Overrides the system BIOS selector jumper and
selects the BIOS with BIOS_SEL.
0 = No BIOS override
1 = BIOS override
D5
BIOS_SEL
BIOS Select
— Selects the system BIOS when BIOS_OR is set.
0 = Backup BIOS selected
1 = Primary BIOS selected
D4-D0
Reserved
These bits have no function.