PORTIBM PC Portable (uses same BIOS as XT) AAE8-AAEB - 8514/A and compatible - WRITE MASK
Desc:	specify which bit planes are updates when a pixel is written
Notes:	supported by ATI Mach8 and Mach32 chipsets
	supported by S3 chipsets when PORTIBM PC Portable (uses same BIOS as XT) 03D4h register 40h bit 0 is set
SeeAlso: PORTIBM PC Portable (uses same BIOS as XT) A6E8h,PORTIBM PC Portable (uses same BIOS as XT) AEE8h

AAE8w -W  drawing control: write mask
AAE8d RW  (S3) drawing control: write mask for 32bpp modes