INT 1A - PCMCIA Socket Services v1.00 - REGISTER STATUS CHANGE CALLBACK         
	AH = 81h
	DS:DX -> callback routine (see #00657) or 0000h:0000h to disable
Return: CF clear if successful
	    AH destroyed
	CF set on error
	    AH = error code (see #00656)
Note:	the callback will be invoked on any socket changes whose notification
	  has not been disabled with the status change enable mask; it may be
	  invoked either while processing a hardware interrupt from the adapter
	  or while processing the following Socket Services request
SeeAlso: AH=80h"PCMCIA",AH=82h"PCMCIA"


(Table 00657)
Values PCMCIA callback routine is invoked with:
	AL = adapter number
	BH = status change interrupt enable mask (see #00658)
	BL = socket number
	DH = current socket status (see #00659)
	DL = current card status (see #00660)
Return: all registers preserved
Notes:	the callback may be invoked during a hardware interrupt, and may not
	  call on Socket Services
	the callback will be invoked once for each socket with a status change


Bitfields for PCMCIA status change interrupt enable mask:
Bit(s)	Description	(Table 00658)
 7	card detect change
 6	ready change
 5	battery warning change
 4	battery dead change
 3	insertion request
 2	ejection request
 1-0	reserved (0)


Bitfields for PCMCIA current socket status:
Bit(s)	Description	(Table 00659)
 7	card changed
 6	reserved (0)
 5	card insertion complete
 4	card ejection complete
 3	card insertion request pending
 2	card ejection request pending
 1	card locked
 0	reserved (0)


Bitfields for PCMCIA current card status:
Bit(s)	Description	(Table 00660)
 7	card detect
 6	ready
 5	battery voltage detect 2 (battery warning)
 4	battery voltage detect 1 (battery dead)
 3-1	reserved (0)
 0	write protected