Octagon Systems XE-700, Reference Manual

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mov dx,0ffffh
int 17h
}
Read I/O
Function: efh
Subfunction: 02h
Purpose: To read from an I/O port.
Calling registers: AH efh
AL 02h
DX ffffh
Return registers: AL Port A data
Ah Port B data
BL Port C data
Carry flag cleared if successful
Carry flag set if error
AL Error code
Comments: This function is used to read from the
I/O.
Programming example:
/* Inline assembly code for Borland C++ 3.1 */
asm {
mov ax,0efoch
mov dx,0ffffh
int 17h
mov aData,al
mov bData,ah
mov cData,bl
}
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