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Chapter 5 - XVME BIOS FUNCTIONS
5.1
XVME BIOS FUNCTIONS
The XVME-678/688 BIOS contains a series of functions that are accessible to user programs, to assist
in configuring and using the VMEbus Interface Control and Status Registers. These functions spare the
user from having to directly access and manipulate the XVME registers, and provide a compatibility
buffer in case future XVME
PCI
AT register maps and bit definitions change. It is recommended that these
functions, rather than direct access, be used.
The XVME BIOS functions are accessed via INT 15h function AFh (i.e., AH
=
AFh). In addition to the
INT 15h interface, the Xycom BIOS Signature area includes a call entry point to the XVME BIOS
functions. The individual function to be performed is identified by an 8-bit sub function number in AL.
Subfunction numbers indicate the group (most significant hex digit of sub function number) and the index
(least significant hex digit of subfunction number). When using the call entry, it is not necessary to load
AH with AFh.
The following code fragment (in assembly) shows how to perform subfunction OOH (Identify XVME
Model) using Interrupt 15h. This method is the easiest, but may not work when running in protected
mode.
Failed:
MOV
INT
JC
AX,OAFOOH
15H
Failed
5-1
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