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2F121C

Category: DOS kernel
Flags: Undocumented function

INT 2F - DOS 3.0+ internal - CHECKSUM MEMORY

	AX = 121Ch
	DS:SI -> start of memory to checksum
	CX = number of bytes
	DX = initial checksum
	SS = DOS DS (must be using a DOS internal stack)
Return: AX, CX destroyed
	DX = checksum
	DS:SI -> first byte after checksummed range
Notes:	used by DOS to determine day count since 1980/1/1 given a date
	supported by DR DOS 5.0+
SeeAlso: AX=121Dh

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  Copyright 2000   by Ralf Brown     Updated Jul 2000