Chapter 4 – Programming
4-11
Read Configuration Byte
This function reads individual bytes from the configuration space of the VMEbus
interface.
ENTRY:
[AH]
BIOS_FUNCTION_ID = B1h
[AL]
BIOS_SUBFUNCTION_ID = 08h
[BH]
Bus Number (0-255)
[BL]
Device Number in upper 5 bits
Function Number is bottom 3 bits
[DI]
Register Number (0...255)
EXIT:
[CL]
Byte Read
[AH]
Return Code:
00h = Successful
87h = Bad Register Number
[CF]
Completion Status, set = error, reset = success
Read Configuration Word
This function reads 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
[AL]
BIOS_SUBFUNCTION_ID = 09h
[BH]
Bus Number (0-255)
[BL]
Device Number in upper 5 bits
Function Number is bottom 3 bits
[DI]
Register Number (0, 2, 4, ...254)
EXIT:
[CL]
Word Read
[AH]
Return Code:
00h = Successful
87h = Bad Register Number
[CF]
Completion Status, set = error, reset = success
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