Int 21/AH=58h

DOS 5+ - GET OR SET UMB LINK STATE

AH = 58h
AL = subfunction
02h get UMB link state
Return:
AL = current link state
00h UMBs not part of DOS memory chain
01h UMBs in DOS memory chain
03h set UMB link state
BX = new link state
0000h remove UMBs from DOS memory chain
0001h add UMBs to DOS memory chain

Return:
CF clear if successful
CF set on error
AX = error code (01h) (see #01680)

Notes: A program which changes the UMB link state should restore it before terminating. UMBs will only be available if CONFIG.SYS contains the line DOS=UMB, the UMBs have been linked into the memory chain with AX=5803h, and the allocation strategy has been set to include high memory with AX=5801h

See Also: #01687 - #02766 at INT 2F/AX=4310h

Category: DOS Kernel - Int 21h - D

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