MEM 0040h:00A8h - VIDEO (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors./MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines./VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) - POINTER TO VIDEO SAVE POINTER TABLE
Size:	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.
SeeAlso: INT 10/AH=1Ch


Format of Video Save Pointer Table [EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors./VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers./MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. only]:
Offset	Size	Description	(Table M0037)
 00h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to Video Parameter Table
 04h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to Parameter Dynamic Save Area, else 0 [EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors./VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. only]
 08h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to Alphanumeric Character Set Override, else 0
 0Ch	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to Graphics Character Set Override, else 0
 10h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	[VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. only] ptr to Secondary Save Pointer Table, must be valid
 14h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	reserved, zero
 18h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	reserved, zero
Note: table initially in ROM(Read-Only Memory) A memory for program storage which may not be changed by the program as it runs., copy to RAM(Random Access Memory)	See also DRAM, SRAM. to alter, then update 40h:A8h.
 

Format of Secondary Video Save Pointer Table [VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. only]:
Offset	Size	Description	(Table M0038)
 00h	WORD	Length of this table in bytes, including this word (1Ah)
 02h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to Display Combination Code Table, must be valid
 06h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to second Alphanumeric Character Set Override, else 0
 0Ah	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to User Palette Profile Table, else 0
 0Eh	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	reserved, zero
 12h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	reserved, zero
 16h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	reserved, zero
Note: table initially in ROM(Read-Only Memory) A memory for program storage which may not be changed by the program as it runs., copy to RAM(Random Access Memory)	See also DRAM, SRAM. to alter, then alter Save Ptr Table.
 

Format of Display Combination Code Table [VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. only]:
Offset	Size	Description	(Table M0039)
 00h	BYTE	Number of entries in the DCC(Display Combination Code) A number which indicates both the type of display adapter board and the type of monitor attached to the video board. table at offset 04h
 01h	BYTE	Version number
 02h	BYTE	Maximum display type code that can appear in DCC(Display Combination Code) A number which indicates both the type of display adapter board and the type of monitor attached to the video board. table
 03h	BYTE	reserved
 04h 2N BYTEs	Each pair of bytes gives a valid display combination, one
		  display type per byte (see #M0040)


(Table M0040)
Values for Display Combination display type:
 00h	 no display
 01h	 MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC.  See also CGAColor Graphics Adapter, HGC. with mono display
 02h	 CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC.  See also HGC, MDA. with color display
 03h	 reserved
 04h	 EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors. with color display
 05h	 EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors. with mono display
 06h	 Professional Graphics Controller
 07h	 VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. with mono display
 08h	 VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. with color display
 09h	 reserved
 0Ah	 MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. with digital color display
 0Bh	 MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. with analog mono display
 0Ch	 MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. with analog color display
 FFh	 unrecognised video system
SeeAlso: #M0039
 

Format of Video Parameter Table [EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. only]:
Offset	Size	Description	(Table M0041)
 00h-03h	Modes 00h-03h in 200-line CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC.  See also HGC, MDA. emulation mode
 04h-0Eh	Modes 04h-0Eh
 0Fh-10h	Modes 0Fh-10h when only 64kB RAM(Random Access Memory)	See also DRAM, SRAM. on adapter
 11h-12h	Modes 0Fh-10h when >64kB RAM(Random Access Memory)	See also DRAM, SRAM. on adapter
 13h-16h	Modes 00h-03h in 350-line mode
 17h		VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. Modes 00h or 01h in 400-line mode
 18h		VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. Modes 02h or 03h in 400-line mode
 19h		VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. Mode  07h in 400-line mode
 1Ah-1Ch	VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. Modes 11h-13h
Note:	An array of 23 [EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.] or 29 [VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.] elements, each element being 64
	  bytes long.  Elements appear in the above order.
 

Format of Video Parameter Table element [EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. only]:
Offset	Size	Description	(Table M0042)
 00h	BYTE	Columns on screen		  (see 40h:4Ah)
 01h	BYTE	Rows on screen minus one	  (see 40h:84h)
 02h	BYTE	Height of character in scan lines (see 40h:85h)
 03h	WORD	Size of video buffer		  (see 40h:4Ch)
 05h  4 BYTEs	Values for Sequencer Registers 1-4
 09h	BYTE	Value for Miscellaneous Output Register
 0Ah 25 BYTEs	Values for CRTC Registers 00h-18h
 23h 20 BYTEs	Values for Attribute Controller Registers 00h-13h
 37h  9 BYTEs	Values for Graphics Controller Registers 00h-08h
 

Format of Video Parameter Table [MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. only] {guesswork from inspection}:
Offset	Size	Description	(Table M0043)
    - 16 triplet BYTEs of R,G,B DAC(Digital-to-Analog Converter) A hardware device (in its simplest form, nothing more than a set of interconnected resistors) which converts a digital number into an analog signal whose voltage is proportional to the value of the digital number.  VGAVideo Graphics Array and later color video boards use DACs to convert color values into the analog signals sent to the display; sound boards normally use DACs as well. info for 16 colors;
    - An array of 11 elements, each element being 32 bytes long.
	  Elements appear in the order:
		Modes 00h,01h in 200-line mode for digital displays
		Modes 00h,01h in 400-line mode for analog displays
		Modes 02h,03h in 200-line mode for digital displays
		Modes 02h,03h in 400-line mode for analog displays
		Modes 04h,05h in 200-line mode for digital displays
		Modes 04h,05h in 400-line mode for analog displays
		Mode  06h in 200-line mode for digital displays
		Mode  06h in 400-line mode for analog displays
		Mode  11h
		Mode  13h in 200-line mode for digital displays
		Mode  13h in 400-line mode for analog displays
 

Format of Video Parameter Table element [MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. only]:
Offset	Size	Description	(Table M0044)
 00h	BYTE	Columns on screen		  (see 40h:4Ah)
 01h	BYTE	Rows on screen minus one	  (see 40h:84h)
 02h	BYTE	Height of character in scan lines (see 40h:85h)
 03h	WORD	Size of video buffer		  (see 40h:4Ch)
 05h	WORD	??? always zero
 07h 21 BYTEs	Video data registers 00h-14h to port 3D5h indexed by 3D4h
 1Ch	BYTE	PEL Mask to port 3C6h
 1Dh	BYTE	CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC.  See also HGC, MDA. Mode Control to port 3D8h
 1Eh	BYTE	CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC.  See also HGC, MDA. Border Control to port 3D9h
 1Fh	BYTE	Extended Mode Control to port 3DDh
 

Format of Video Parameter Dynamic Save Area [EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. only]:
Offset	Size	Description	(Table M0045)
 00h 16 BYTEs	Last data written to Attribute Contr. Palette Registers 0-15
 10h	BYTE	Last data written to Attribute Controller Overscan RegisterOn a display adapter, the control register which specifies the color to be displayed in the overscan area.
 11h-FFh	Reserved
		Note: Need for table was that EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors. registers were write-only.
		Note: If default values (from the Video Parameter Table) are
		      over-ridden at a mode set by the VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. User Palette Profile
		      Table, then the Dynamic Save Area is updated with the
		      default values, not the User Profile ones.
 

Format of Alphanumeric Character Set Override:
Offset	Size	Description	(Table M0046)
 00h	BYTE	Length in bytes of each character in font table
 01h	BYTE	Character generator RAM(Random Access Memory)	See also DRAM, SRAM. bank to load, 0=normal
 02h	WORD	Number of characters in font table, normally 256
 04h	WORD	Code of first character in font table, normally 0
 06h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to font table
 0Ah	BYTE	Displayable rows (FFh=use maximum calculated value)
 0Bh	BYTEs	Array of mode values to which this font is to pertain
	BYTE	FFh end of array
 

Format of Second Alphanumeric Character Set Override:
Offset	Size	Description	(Table M0047)
 00h	BYTE	Length in bytes of each character in font table
 01h	BYTE	Character generator RAM(Random Access Memory)	See also DRAM, SRAM. bank to load, normally non-zero
 02h	BYTE	reserved
 03h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to font table
 07h	BYTEs	Array of mode values to which this font is to pertain
	BYTE	FFh end of array
Note:	Authorities differ, some say same as first override above, but IBMInternational Busiuness MachinesInternational Busiuness Machines) A hardware, software and other service technology company founded in 1911.
	  says it is as shown above
 

Format of Graphics Character Set Override:
Offset	Size	Description	(Table M0048)
 00h	BYTE	Number of displayable character rows
 01h	WORD	Length in bytes of each character in font table
 03h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to font table
 07h	BYTEs	Array of mode values to which this font is to pertain
	BYTE	FFh end of array
 

Format of User Palette Profile Table [VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. only]:
Offset	Size	Description	(Table M0049)
 00h	BYTE	Underlining: 01h=enable in all alphanumeric modes
			     00h=enable in monochrome alphanumeric modes only
			     FFh=disable in all alphanumeric modes
 01h	BYTE	reserved
 02h	WORD	reserved
 04h	WORD	Number (0-17) of Attribute Controller registers in table
 06h	WORD	Index (0-16) of first Attribute Controller register in table
 08h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to table of Attribute Controller registers to override
			Table is an array of BYTEs.
 0Ch	WORD	Number (0-256) of video DAC(Digital-to-Analog Converter) A hardware device (in its simplest form, nothing more than a set of interconnected resistors) which converts a digital number into an analog signal whose voltage is proportional to the value of the digital number.  VGAVideo Graphics Array and later color video boards use DACs to convert color values into the analog signals sent to the display; sound boards normally use DACs as well. Color registers in table
 0Eh	WORD	Index (0-255) of first video DAC(Digital-to-Analog Converter) A hardware device (in its simplest form, nothing more than a set of interconnected resistors) which converts a digital number into an analog signal whose voltage is proportional to the value of the digital number.  VGAVideo Graphics Array and later color video boards use DACs to convert color values into the analog signals sent to the display; sound boards normally use DACs as well. Color register in table
 10h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ptr to table of video DAC(Digital-to-Analog Converter) A hardware device (in its simplest form, nothing more than a set of interconnected resistors) which converts a digital number into an analog signal whose voltage is proportional to the value of the digital number.  VGAVideo Graphics Array and later color video boards use DACs to convert color values into the analog signals sent to the display; sound boards normally use DACs as well. Color registers to override
			Table is ??? triplets ??? of BYTEs???
 14h	BYTEs	array of mode values to which this profile is to pertain
	BYTE	FFh end of array