Interrupt 2Fh Function 1686h

mov ax, 1686h ; Detect Interrupt 31h Services

int 2Fh ; multiplex interrupt

or ax,0

jz int31_avail ; ax is zero if interrupt 31h services available

Detect Interrupt 31h Services (Interrupt 2Fh Function 1686h) determines whether a set of protected-mode functions are available for use by protected-mode applications. Applications use the Interrupt 31h services to allocate and manage protected-mode memory.

Parameters

This function has no parameters.

Return Value

The return value is zero in the AX register if the Interrupt 31h services are available. Otherwise, the AX register contains a nonzero value.

Comments

Both standard- and 386 enhanced-mode Windows support the Interrupt 31h services. Interrupt 31h services are only supported for protected-mode programs.