Interrupt 2Fh Function 4300h Get HIMEM.SYS Installed State

mov ax, 4300h ;Get HIMEM.SYS Installed State

int 2Fh ;Multiplex Interrupt

cmp al, 80h ;80h means installed

Get HIMEM.SYS Installed State (Interrupt 2Fh Function 4300h) determines whether the extended-memory manager, HIMEM.SYS, has been loaded.

Parameters

This function has no parameters.

Return Value

The AL register contains 80h if the driver has been loaded or 00h if it has not.

Comments

The HIMEM.SYS driver provides a set of functions that programs use to independently manage extended memory. Although programs can also use these functions to manage the high memory area (HMA) and upper memory blocks (UMBs), programs should not do so if MS-DOS already manages these areas.

This function returns the installed state of any extended-memory manager as long as the manager conforms to the Lotus/Intel/Microsoft/AST eXtended Memory Specification (XMS) version 2.0.

See Also

Interrupt 2Fh Function 4310h Get HIMEM.SYS Entry-Point Address