Chapter 4 – Programming
4-12
Read Configuration Dword
This function reads individual dwords from the configuration space of the VMEbus
interface. The Register Number parameter must be a multiple of four (i.e., bits 0 and 1
must be set to 0).
ENTRY:
[AH]
BIOS_FUNCTION_ID = B1h
[AL]
BIOS_SUBFUNCTION_ID = 0Ah
[BH]
Bus Number (0-255)
[BL]
Device Number in upper 5 bits
Function Number is bottom 3 bits
[DI]
Register Number (0, 4, 8, ...252)
EXIT:
[ECX]
Word Read
[AH]
Return Code:
00h = Successful
87h = Bad Register Number
[CF]
Completion Status, set = error, reset = success
Write Configuration Byte
This function writes individual bytes from the configuration space of the VMEbus
interface.
ENTRY:
[AH]
BIOS_FUNCTION_ID = B1h
[AL]
BIOS_SUBFUNCTION_ID = 0Bh
[BH]
Bus Number (0-255)
[BL]
Device Number in upper 5 bits
Function Number is bottom 3 bits
[DI]
Register Number (0...255)
[CL]
Byte Value to Write
EXIT:
[AH]
Return Code:
00h = Successful
87h = Bad Register Number
[CF]
Completion Status, set = error, reset = success
Write Configuration Word
This function writes individual words from the configuration space of the VMEbus
interface. The Register Number parameter must be a multiple of two (i.e., bit 0 must be
set to 0).
ENTRY:
[AH]
BIOS_FUNCTION_ID = B1h
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