PORTIBM PC Portable (uses same BIOS as XT) 42E8 - 8514/A and hardware-compatible video cards
Note:	supported by S3 chipsets when PORTIBM PC Portable (uses same BIOS as XT) 03D4h register 40h bit 0 is set

42E8w R-  Misc. control: Subsystem Status (see #P1018)
42E8w -W  Misc. control: Subsystem Control (see #P1019)


Bitfields for 8514/A Subsystem Status register:
Bit(s)	Description	(Table P1018)
 15-8	(8514/A) reserved
 13	(S3) ???
 12-8	(S3) ???
 7	pixel length (0 = four bits, 1 = eight bits)
 6-4	reserved
 3	FIFO empty (interrupt generated if enabled)
 2	FIFO overflow (interrupt generated if enabled)
 1	Graphics Engine busy (interrupt generated if enabled)
 0	vertical sync (interrupt generated if enabled)
SeeAlso: #P1019


Bitfields for 8514/A Subsystem Control Register:
Bit(s)	Description	(Table P1019)
 15-14	GP_RESET
      W	00 no change
	01 normal operation
	10 reset graphics processor and FIFO
	11 reserved
 13-12	reserved
 11   W	enable interrupt when graphics processor idle
 10   W	enable interrupt on invalid I/O (FIFO overlow)
 9    W	enable interrupt if inside scissors region
 8    W	enable vertical blanking interval interrupt
 6-4 R	monitor ID (8514/A)
 7-4	reserved (S3)
 3	acknowledge idle interrupt (and clear)
 2	acknowledge invalid I/O interrupt (and clear)
 1	acknowledge inside-scissors interrupt (and clear)
 0	acknowledge vertical blanking interrupt (and clear)
SeeAlso: #P1018