INT 21 - DOS 3.4/4.0 - GET CURRENT CPSW STATE                                   
	AX = 3303h
Return: DL = current CPSW
Notes:	this function and AX=3304h were intended to support a proposed
	  code-page switching flag (using the WORD at offset 0Ch in the DOS
	  directory entry for codepage information); however, this function
	  has always been a NOP in public releases of DOS and OS/2.
	  See DOS Internals Chapter 2 for more information.
	the released MS-DOS 4.00 IO.SYS has an undocumentedInformation about a product which is not publicly available from the manufacturer, and must be determined by reverse-engineering (disassembly, trial-and-error, etc.).	 Undocumented information tends to change -- often dramatically -- between successive revisions of a product, since the manufacturer has no obligation to maintain compatibility in behavior which is not explicitly stated. CONFIG.SYS
	  directive named CPSW= and that beside others the MS-DOS 4.00 ATTRIB
	  supported a number of undocumentedInformation about a product which is not publicly available from the manufacturer, and must be determined by reverse-engineering (disassembly, trial-and-error, etc.).	 Undocumented information tends to change -- often dramatically -- between successive revisions of a product, since the manufacturer has no obligation to maintain compatibility in behavior which is not explicitly stated. special parameters for
	  "predefined" Extended Attributes (EAs) e.g.
	  ATTRIB filename [(CODEPAGE|CP)[=new_value]].
	this function does not use any of the DOS-internal stacks and may
	   thus be called at any time. It is directly dispatched from
	   the INT 21h entry point with interrupts disabled.
SeeAlso: AX=3304h