INT 21 U - DR DOS 5.0+ - HISTORY BUFFER CONTROL                                 
	AX = 4456h
	DL = control flags (see #01582)
Return: AL = previous value of state flags (see #01583)
Note:	DR DOS 6.0 only checks bit 0 and ignores the rest of DL
SeeAlso: #01584


Bitfields for control flags:
Bit(s)	Description	(Table 01582)
 0	whose buffer: 0=application, 1=COMMAND.COM
---Novell DOS 7---
 1	toggle HISTORY usage
 2	toggle INSERT state
Note:	only one bit at a time may be used


Bitfields for state flags:
Bit(s)	Description	(Table 01583)
 0	HISTORY buffer enabled
 1	INSERT enabled
 2-5	unused
 7	whose buffer: 0=application, 1=COMMAND.COM