INT D4 - PC-MOS/386 v5.01 - SWAP CONTROL BLOCK DATA OF SCB OR TCB               
	AH = 2Ah
	BX = offset into control block at which to start swap
	CX = number of bytes to swap
	DX = segment/selector of control block obtained via AH=26h or AH=27h
	DS:SI -> buffer containing new data and to receive current data
Return: CF clear if successful
	CF set on error
	    AX = error code (see also #01680 at INT 21/AH=59h/BX=0000h)
		05h access denied due to an invalid segment/selector
Note:	the interrupts are disabled during the swap to prevent corruption
SeeAlso: AH=26h,AH=27h,AH=28h,AH=29h