The following is a concantenation of the messages from Joel Seiferas,
70516,1704 concerning the IBM Enhanced Graphics	Adapter	and its	BIOS
interfaces.  Hopefully,	this will help until IBM releases "official"
information....	 connie


 #: 80780      Sub-topic 1 - User Updates/Fixes
Sb: EGA	doc.
    26-Dec-84  19:01:04
Fm: Joel Seiferas   70516,1704
To: EGA	owners


     The IBM Enhanced Graphics Adapter is comes	without	usage
instructions, so the following message should be useful	to purchasers.

Date: Fri, 21 Dec 84 22:50:00 EST
From: BrucCowan%UMich-MTS.Mailnet@MIT-MULTICS.ARPA
Subject: IBM Enhanced Graphics Adaptor Information

Here are some very brief instructions for the BIOS interface for the
enhanced graphics adaptor. No guarantees about accuracy. Hope they are
of some	use. I haven't figured out most of them. Parenthesized comments
indicate some things I have found out. I'd like any more information
anyone comes up	with.

EGA extensions to ROM BIOS INT 10H.

(AH)=0 Set mode
  (AL) 0-7 as before (7	is now user selectable)
       D  graphics 320x200 on color (5153) monitor
       E  graphics 640x200
       F  graphics 640x350 on monochrome monitor
      10  graphics 640x350 on 5154 monitor
     All above have graphics memory at A000:0. If you use one of the
     old modes,	the memory appears at the standard address for the
     old adaptors (B000:0 or B800:0).

(AH)=10	Set palette registers
  (AL)=0 Set individual	palette	register
    BL = palette register to set, BH = value to	set
  (AL)=1 Set overscan register
    BH = value to set
  (AL)=2 Set all palette registers and overscan
    ES:DX points to a 17 byte table
    bytes 0-15 are the palette values, respectively
    byte 16 is the overscan value
  (AL)=3 Toggle	intensify/blinking bit
    BL - 0 enable intensify
    BL - 1 enable blinking

(AH)=11	Character generator routine
	Note: This call	will initiate a	mode set.
  (AL)=00 User alpha load
	ES:BP -	pointer	to user	table
	CX    -	count to store
	DX    -	character offset into table
	BL    -	block to load
	BH    -	number of bytes	per character
  (AL)=01 ROM monochrome set
	BL    -	block to load
  (AL)=02 ROM 8x8 double dot
	BL    -	block to load
  (AL)=03 Set block specifier
	BL    -	char gen block specifier
		D3-D2 attr bit 3 one, char gen 0-3
		D1-D0 attr bit 3 zero, char gen	0-3
	Note: When using AL=03,	a function call	AX=1000H, BX=0712H is
	      recommended to set the color planes resulting in 512
	      characters and 8 consistent colors.


(UA RE T):

 #: 80784      Sub-topic 1 - User Updates/Fixes
Sb: EGA	doc. (cont.)
    26-Dec-84  19:05:23
Fm: Joel Seiferas   70516,1704
To: EGA	owners (cont.)


  Note:	The following interface	(AL=1x)	is similar in function to
	(AL=0x)	except that:
		- page 0 must be active
		- points (bytes/char) will be recalculated
		- rows will be calculated from the following:
			int (200 or 350) / points - 1
		- CRLEN	will be	calculated from:
			(rows+1)*CRCOLS*2
		- the CRTC will	be reprogrammed	as follows:
			R09H = points -	1    max scan line
				R09H only done in mode 7
			R0AH = points -	2    cursor start
			R0BH = 0	     cursor end
			R12H =		     vert disp end
			       (rows+1)*points-1
			R14H = points	     underline loc
	The above register calculations	must be	close to the original
	table values or	undetermined results will occur.

	Note: The following interface is designed to be	called only
	      immediately after	a mode set. Failure to adhere to this
	      practice may cause undetermined results.

  (AL)=10 User alpha load
	ES:BP -	pointer	to user	table
	CX    -	count to store
	DX    -	character offset into table
	BL    -	block to load
	BH    -	number of bytes	per character
  (AL)=11 ROM monochrome set
	BL    -	block to load
  (AL)=12 ROM 8x8 double dot
	BL    -	block to load  (this gives 43 lines in char mode)

	Note: The following interface is designed to be	called only
	      immediately after	a mode set. Failure to adhere to this
	      practice may cause undetermined results.
  (AL)=20 User graphics	chars  INT 01FH	(8x8)
	ES:BP -	pointer	to user	table
  (AL)=21 User graphics	chars
	ES:BP -	pointer	to user	table
	CX    -	points (bytes/char)
	BL    -	row specifier
		BL = 0 user
		       DL - rows
		BL = 1 14 (0EH)
		BL = 2 25
		BL = 3 43
  (AL)=22 ROM 8x14 set
	BL    -	row specifier
  (AL)=23 ROM 8x8 double dot
	BL    -	row specifier (this seems wrong, use BL=# rows)

(UA RE T):

 #: 80785      Sub-topic 1 - User Updates/Fixes
Sb: EGA	doc. (concl.)
    26-Dec-84  19:07:04
Fm: Joel Seiferas   70516,1704
To: EGA	owners


  (AL)=30 Information
		CX - points
		DL - rows
	BH - 0 return current INT 1FH ptr
		ES:BP -	ptr to table
	BH - 1 return current INT 44H ptr
		ES:BP -	ptr to table
	BH - 2 return ROM 8x14 ptr
		ES:BP -	ptr to table
	BH - 3 return ROM double dot
		ES:BP -	ptr to table
	BH - 4 return ROM double dot (top)
		ES:BP -	ptr to table
	BH - 5 return ROM alpha	alternate 9x14
		ES:BP -	ptr to table

(AH)=12	Alternate select
  (BL)=10 Return EGA information
	BH = 0 - color mode in effect
	   = 1 - monochrome mode in effect
	BL = memory value
		0 0 - 064K	  0 1 -	128K
		1 0 - 192K	  1 1 -	256K
	CH = feature bits
	CL = switch setting
  (BL)=20 Select alternate print screen	routine

(AH)=13	Write string
  This is the same as documented in the	PC/AT Technical	Reference
  BIOS listing (but is new for non ATs).

(UA RE T):


 #: 80885      Sub-topic 1 - User Updates/Fixes
Sb: 43-line mode
    27-Dec-84  06:25:36
Fm: Joel Seiferas   70516,1704
To: EGA	owners


     Following the reposted underground	EGA documentation from Bruce
Cowan, I finally managed to look at 43-line mode on the	monochrome
display.  Here is the hex for a	tiny .com program to change to that
mode:


B80700CD10B411B012B300CD10CD20

;checksum 1440


To use the new mode, one should	avoid ANSI.SYS or modify it to allow 43
lines.	Also, a	cursor is still	needed.

(UA RE T):