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April 10, 1991 1.0 INTRODUCTION 1.1 PURPOSE The purpose of this document is to aid professional programmers who wish to write software to use the high resolution modes supported by the VGAWONDER video board. Working knowledge of EGA/VGA graphics and assembly language programming is required and assumed. The document describes several features unique to the VGAWONDER and how each high resolution mode is similar or is different compared to standard VGA modes. It does not contain any programming information about standard EGA/VGA modes. Refer to the Reference list in the appendix for recommended EGA/VGA programmer's references. 1.2 CONVENTIONS The code segments contained in this document follow the conventions of the MicroSoft MASM assembler. Numbers given in hexadecimal end with a lower case h. 2.0 FEATURES OF THE VGA BOARD 2.1 STANDARD VIDEO MODES AH = 0 ;set video mode AL = MODE/ RESOLUTION DIM/ START TYPE COLOR ADDRESS --------------------------------------------------------------- 0h color/alpha 640x200 40x25/ BW b800:0h 1h color/alpha 640x200 40x25/ 16 b800:0h 2h color/alpha 640x200 80x25/ BW b800:0h 3h color/alpha 640x200 80x25/ 16 b800:0h 0* color/alpha 640x350 40x25/ BW b800:0h 1* color/alpha 640x350 40x25/ 16 b800:0h 2* color/alpha 640x350 80x25/ BW b800:0h 3* color/alpha 640x350 80x25/ 16 b800:0h 0+ color/alpha 720x400 40x25/ BW b800:0h 1+ color/alpha 720x400 40x25/ 16 b800:0h 2+ color/alpha 720x400 80x25/ BW b800:0h 3+ color/alpha 720x400 80x25/ 16 b800:0h 4h color/graphics 320x200 40x25/ 4 b800:0h 5h color/graphics 320x200 40x25/ BW b800:0h 6h color/graphics 320x200 80x25/ BW b800:0h 7h mono/alpha 720x350 80x25/ BW b000:0h 0dh color/graphics 320x200 40x25/ 16 a000:0h 0eh color/graphics 640x200 80x25/ 16 a000:0h 0fh mono/graphics 640x350 80x25/ BW a000:0h 10h color/graphics 640x350 80x25/ 16 a000:0h 11h color/graphics 640x480 80x30/ BW a000:0h 12h color/graphics 640x480 80x30/ 16 a000:0h 13h color/graphics 320x200 80x25/256 a000:0h 2.2 ENHANCED VIDEO MODES 23h color/alpha 1056x350 132x25/16 b800:0h 27h mono/alpha 1056x350 132x25/BW b000:0h 33h color/alpha 1056x352 132x44/16 b800:0h 37h mono/alpha 1056x352 132x44/BW b000:0h 53h color/graphics 800x560 16 a000:0h 54h color/graphics 800x600 16 a000:0h 55h color/graphics 1024X768 16 a000:0h 61h color/graphics 640x400 256 a000:0h 62h color/graphics 640x480 256 a000:0h 63h color/graphics 800x600 256 a000:0h 64h color/graphics 1024x768 256 a000:0h 65h color/graphics 1024x768 16 a000:0h 67h color/graphics 1024x768 4 a000:0h 2.3 REQUIRED CONFIGURATIONS The enhanced modes have differing memory requirements. Some enhanced modes are supported only on certain monitor types or hardware revisions. The following chart describes the requirements for each enhanced mode. Mode# Resolution Colors/ Memory Monitors (hex) Palette Required Supported ----------------------------------------------------------------- 23 132x25 16/64 512K 1,2,5 27 132x25 B&W 512K 1,2,5 33 132x44 16/64 512K 1,2,5 37 132x44 B&W 512K 1,2,5 54 800x600 16/256K 256K 5 55* 1024X768 256/256K 256K 4,5 61 640x400 256/256K 512K 3,4,5 62 640x480 256/256K 512K 3,4,5 63 800x600 256/256K 512K 5 64# 1024x768 256/256K 1M 4,5 65 1024x768 16/256K 512K 4,5 67 1024x768 4/16 256K 4,5 Monitors: (1) TTL mono (2) EGA (3) VGA (4) IBM 8514 (5) Multisync * not supported on VGAWONDER V3 # only supported on VGAWONDER+ 1Mb 3.0 DETERMINING THE STATUS OF THE CARD The VGA BIOS features some special functions which will allow the programmer to determine if a compatible VGA board is installed and how the card is configured within his program. 3.1 IDENTIFYING THE VIDEO CARD All EGA and VGA display adapters manufactured by ATI Technologies will contain the character string: "761295520" starting at address: C000:31. VGA boards which are based on the ATI VGA chip set are identified by the character string "31" at address C000:40. The card is further identified by 2 bytes. The definition of the byte at address C000:42 is: bit 0 = 0 16-bit VGA board bit 0 = 1 8-bit VGA board bit 1 = 1 mouse port present on display adapter bit 2 = 1 supports non-interlaced 1024x768 bit 3 = 1 microchannel product bit 4 = 1 contains programmable video clock chip bit 5-7 = not currently defined The character at address C000:43 contains the revision of the VGA gate array. Currently, the following models exist and other revisions may follow in the future. '1' = 18800 '2' = 18800-1 '3' = 28800-2 '4' = 28800-4 '5' = 28800-5 3.2 DETERMINING THE MONITOR TYPE The following assembler code segment can be used to determine for which monitor the VGA board is currently configured. cli mov dx,EXTENDED_REG mov al,DATA_I out dx,al inc dx in al,dx sti and al,0fh returns al = 0 EGA monitor 1 PS/2 monochrome monitor 2 TTL monochrome monitor 3 PS/2 color monitor 4 RGB color monitor 5 Multisync monitor 7 PS/2 8514 monitor 8 Seiko 1430 9 NEC MultiSync 2A a Crystalscan 860/Tatung 1439 b NEC MultiSync 3D c TVM 3M d NEC MultiSync XL e TVM 2A f TVM 3A where EXTENDED_REG = see section 4.41 in this document DATA_I = 0bbh Note : We reserve the right to add more monitor types at any time. We recommend that if an undefined value is returned that the program assumed that a multisync is installed. 3.3 DETERMINING MEMORY SIZE In terms of memory determination, ATI VGA chipsets fall into 3 groups. The first group is identified as types 1 and 2 (see section 3.31). The second group is identified as type 3 and the third group as type 4 or 5. All types can be equipped with 256K or 512K of RAM. Only types 4 or 5 may be equipped with 1M of RAM. The following code segment will determine the type of chipset and use the appropriate method to determine memory size. .MODEL small,C .CODE PUBLIC RAMSIZE ; -------------------------------------------------------------------------- ; CALL VALUES: none ; RETURNS VALUES: AX = 256 (100h) for 256K bytes ; 512 (200h) for 512K bytes ; 1024 (400h) for 1024K bytes RAMSIZE PROC NEAR push bx ; Save used register values push dx push ds mov ax, 0c000h mov ds, ax xor ax, ax mov dx, word ptr ds:[0010h] ; Get value of ATI extended register mov bl, byte ptr ds:[0043h] ; Get value of ATI chip version pop ds mov bh, 1 ; Assume 256K ramsize (100h) cmp bl, '3' jae ramsize_V6_up ; Use different method to determine mov al, 0bbh ; memory size of chip version is 3 or cli ; higher out dx, al inc dx in al, dx ; Get ramsize byte for chip versions sti ; 1 & 2 test al, 20h jz eo_ramsize mov bh, 2 ; Set ramsize return value to 512K (200h) jmp short eo_ramsize ; and exit ramsize_V6_up: ; Method used for newer ATI chip versions mov al, 0b0h cli out dx, al inc dx in al, dx ; Get ramsize byte for versions 3-5 sti test al, 10h ; Check if ramsize byte indicates 256K jz ramsize_V7_up ; or 512K bytes mov bh, 2 ; Set ramsize return value to 512K (200h) ramsize_V7_up: ; Check for ramsize for ATI chip cmp bl, '4' ; versions 4 & 5 jb eo_ramsize test al, 8 ; Check if version 5 ATI chip has 1024K jz eo_ramsize mov bh, 4 ; Set ramsize return value to 1024K (400h) eo_ramsize: xor bl,bl ; Zero lower byte of BX mov ax, bx ; Return actual ramsize value in AX pop dx ; Restore BX and DX registers pop bx ret RAMSIZE ENDP ; -------------------------------------------------------------------------- END 3.4 DETERMINING WHETHER A MODE IS SUPPORTED Your VGA board implements an extended video BIOS call which can be used to determine if a particular mode is actually available in the user's current configuration. The following assembler routine demonstrates this technique: push bp mov bp,sp push es mov al,ARG mov ah,12h mov bx,5506h mov bp,0ffffh int 10h mov ax,bp pop es pop bp ret where ARG = mode desired in hexadecimal If this routine returns ax = 0ffffh, that mode is not supported in the current configuration. If the mode is supported, ax will contain the offset start address of the CRTC parameter table for that mode. Note : We recommend this technique as the only reliable means of determining if a particular mode is supported on our EGA or VGA boards. 4.0 PROGRAMMING THE HIGH RESOLUTION MODES 4.1 SETTING THE VIDEO MODE The VGA card can be set into a video mode through the BIOS by using the standard IBM method: AH is set to 0, AL is set to the video mode number, and a call to software interrupt 10h is executed. See sections 2.1 and 2.2 of this manual for a list of available modes. The following example will perform this function: mov ah,0 ;set mode function mov al,MODE ;select video mode int 10h ;make BIOS call by using the video ;interrupt We recommend that programmers select the video mode through BIOS whenever possible rather than programming the mode via the registers. For any particular video mode, the configuration of the internal registers may differ depending on the type of monitor installed. Also, we reserve the right to change the product in a way which would be transparent to BIOS but which would have an impact on software which writes to the registers. 4.2 VIDEO MEMORY ADDRESSING 4.21 ADDRESS RANGE OF VGA BOARD The VGA board uses the RESERVED area designated by IBM for video RAM and the video BIOS (A000 to C7FF). The organization is as follows: Mono text video RAM: B000-B7FF Color text video RAM: B800-BFFF Graphics video RAM: A000-AFFF (upto eight 64k banked pages with 512K RAM) Video BIOS: C000-C7FF I/O Ports: 1CE-ICF, 3B0-3DF 4.22 PAGES and PLANES: There are two memory mapping systems used with VGA graphics modes: Packed pixel and Planar organization. The Packed pixel mapping scheme is associated with pages and uses contiguous memory to describe each pel. IBM VGA mode 13h uses this system. Extended modes 61, 62, 63, and 65h also use the Bit-packed scheme but they use a unique method to select which page is available for reading and writing. The Planar organized memory mapping scheme is associated with planes and uses a bit from each plane to describe a pel. IBM VGA mode 12h uses this system as does Extended modes 54h, 55h and 67h. 4.23 SELECTING MEMORY PAGES: The memory organization of extended modes 61h, 62h, 63h, 64h and 65h are arranged into 64k page segments. The data in each page is displayed on a specific region of the screen image. For example, mode 63h has eight pages. The first page is displayed on the top eighth of the screen image, the second page is displayed on the second eighth of the screen image, and so on. Data can be read or written to one page at a time. The default active page is Page 0. A special code segment is required to be executed before data can be read or written to a specific page. A page selecting code segment is provided below. VGA cards with 256K of RAM have four, those with 512K have eight and those with 1M have 16 pages available. Modes 61h, 62h, 63h and 64h require 1 byte per pel and mode 65h requires 1/2 byte per pel. The following code segment can be used to select the required page: cli mov dx,EXTENDED_REG mov al,PAGE_SELECT out dx,al inc dl in al,dx mov ah,al and ah,PAGE_MASK shl ch,1 or ah,ch mov al,PAGE_SELECT dec dl out dx,ax sti where ch = required page value (0 to 7 for mode 63h for example) PAGE_SELECT = 0B2h PAGE_MASK = 0E1h EXTENDED_REG = value of extended register stored at memory address C000:0010h. See section 4.31 The following is a table that describes the visible range for each extended mode which uses the bit-packed memory organization: Mode 61h (640 x 400 - 256 colors): Page Visible range (column,row) Memory range 0 (0,0) --> (255,102) A0000 - AFFFF 1 (256,102) --> (511,204) A0000 - AFFFF 2 (512,204) --> (127,307) A0000 - AFFFF 3 (128,307) --> (639,399) A0000 - AE7FF Mode 62h (640 x 480 - 256 colors): Page Visible range (column,row) Memory range 0 (0,0) --> (255,102) A0000 - AFFFF 1 (256,102) --> (511,204) A0000 - AFFFF 2 (512,204) --> (127,307) A0000 - AFFFF 3 (128,307) --> (383,409) A0000 - AFFFF 4 (384,409) --> (639,479) A0000 - AAFFF Mode 63h (800 x 600 - 256 colors): Page Visible range (column,row) Memory range 0 (0,0) --> (735,81) A0000 - AFFFF 1 (736,81) --> (671,163) A0000 - AFFFF 2 (672,163) --> (607,245) A0000 - AFFFF 3 (608,245) --> (543,327) A0000 - AFFFF 4 (544,327) --> (479,409) A0000 - AFFFF 5 (480,409) --> (415,491) A0000 - AFFFF 6 (416,491) --> (351,573) A0000 - AFFFF 7 (352,573) --> (799,599) A0000 - A561F Mode 64h (1024 x 768 - 256 colors): Page Visible range (column,row) Memory range 0 (0,0) --> (1023,63) A0000 - AFFFF 1 (0,64) --> (1023,127) A0000 - AFFFF 2 (0,128) --> (1023,190) A0000 - AFFFF 3 (0,191) --> (1023,255) A0000 - AFFFF 4 (0,256) --> (1023,319) A0000 - AFFFF 5 (0,320) --> (1023,383) A0000 - AFFFF 6 (0,384) --> (1023,447) A0000 - AFFFF 7 (0,448) --> (1023,511) A0000 - AFFFF 8 (0,512) --> (1023,575) A0000 - AFFFF 9 (0,576) --> (1023,639) A0000 - AFFFF 10 (0,640) --> (1023,703) A0000 - AFFFF 11 (0,704) --> (1023,767) A0000 - AFFFF 12 spare 13 spare 14 spare 15 spare Mode 65h (1024 x 768 - 16 colors): Page Visible range (column,row) Memory range 0 (0,0) --> (1023,127) A0000 - AFFFF 1 (0,128) --> (1023,255) A0000 - AFFFF 2 (0,256) --> (1023,383) A0000 - AFFFF 3 (0,384) --> (1023,511) A0000 - AFFFF 4 (0,512) --> (1023,639) A0000 - AFFFF 5 (0,640) --> (1023,767) A0000 - AFFFF 6 spare 7 spare 4.3 DETAILS OF EACH EXTENDED VIDEO MODE 4.31 132X25 - Color text (Mode 23h) 132x25 - B&W text (Mode 27h) 132X44 - Color text (Mode 33h) 132X44 - B&W text (Mode 37h) Video Memory Organization: The memory organization of very similar to standard text modes. Only one page of 6,660 bytes (132X25 modes) or 11,616 bytes (132X44 modes) is availible. Video Data Organization: The video data organization is identical to standard text modes. BIOS support All BIOS calls supported on standard text modes are supported. NOTE! It is a good idea to avoid DOS calls when using the 132X44 text modes. Most versions of ANSI.SYS are not compatible with text modes which have more than 25 lines. This is particularly a problem when scrolling the screen. 4.32 800x600 - 16 COLORS (Mode 54h) Video Memory Organization: The memory organization is identical to 16 color IBM EGA/VGA modes and consists of 256K organized into 4 maps of 64K each. One bit from each of the 4 maps is used to compose each pel. The IBM EGA/VGA Map Mask Register is used to select any or all the maps to be updated. A0000:0 -> ---------- | |---------- | | |---------- |----------| | |---------- <===\=======\ | Reserved |----------| | | 60,000 | ----------| Reserved |----------| | | | Plane 0 ----------| Reserved |----------|<===/ 64K Plane 1 ----------| Reserved | | Plane 2 --------- <===========/ Plane 3 Video Data Format: The video data format is identical to the 16 color IBM EGA/VGA modes. Color Mapping: Color selection and palette changing is identical to the 16 color IBM EGA/VGA mode 4.33 1024x768 - 16 COLORS PLANAR (Mode 55h) Video Memory Organization: The memory organization is similar to 16 color IBM EGA/VGA modes and consists of 2 pages of 256K each organized into 4 maps of 64K. One bit from each of the 4 maps is used to compose each pel. The IBM EGA/VGA Map Mask Register is used to select any or all the maps to be updated. Address Page # A000:0 ==> +-----+-----+-----+-----+ | | | | | | | | | | | | | | | 0 | | | | | | | | | | A000:0 ==> +-----+-----+-----+-----+ | | | | | | | | | | | | | | | 1 | | | | | | | | | | +-----+-----+-----+-----+ Map # 0 1 2 3 Selecting Memory Page: The following code segment demonstates how to switch between pages when in this mode. To change the write plane cli mov dx,ATI_REG mov al,PLANE_SELECT out dx,al inc dl in al,dx mov ah,al and ah,WPLANE_MASK shl ch,1 or ah,ch mov al,PLANE_SELECT dec dl out dx,ax sti To change the read plane cli mov dx,ATI_REG mov al,PLANE_SELECT out dx,al inc dl in al,dx mov ah,al and ah,RPLANE_MASK shl ch,1 shl ch,1 shl ch,1 shl ch,1 rol ch,1 or ah,ch mov al,PLANE_SELECT dec dl out dx,ax sti Where ch = page number required ATI_REG = store in location c000:10h PLANE_MASK = 0e1h WPLANE_MASK = 0e1h RPLANE_MASK = 01eh PLANE_SELECT = 0b2h DIFF_RW_PLANE = 008h MISC2_REG = 0beh DATA_I = 0bbh The read and write planes can be changed simultaneously. 4.36 800x600 - 256 COLORS (Mode 63h) Video Memory Configuration: This enhanced resolution mode uses a page memory system unique to this VGA board. The memory is organized into contiguous 64K blocks located at A0000H to AFFFFH. The VGA board must be equipped with 512K of RAM to support this mode. Mode 63h uses eight 64K pages. For information on selecting the active page, refer to section 4.23 "SELECTING MEMORY PAGES" of this document. A0000:0 -> ----------<==============================================\ | |---------- | | | |---------- | | | | | \ | | | | | \ | ----------| | | \ | Page 0 ----------| | \ | Page 1 ---------- ---------- <=\ 480,000 Page 3 \ | | | | \ | | 64K | \ | | | | \ | | | | ---------- <=/=====/ Page 7 Video Data Format: The video data format is identical to IBM VGA mode 13h (320x200-256 color). Each pel is represented by 1 byte. Color Mapping: Color selection and palette changing is identical to VGA mode 13h. Video Data Format: The video data format is identical to the 16 color IBM EGA/VGA modes. Color Mapping: Color selection and palette changing is identical to the 16 color IBM EGA/VGA mode 4.34 640x400 - 256 COLORS (Mode 61h) Video Memory Configuration: This enhanced resolution mode uses a page memory system unique to this VGA board. The memory is organized into contiguous 64K blocks located at A0000H to AFFFFH. A VGA board equipped with 256K or 512K of RAM will support this mode. Mode 61h uses four 64K pages. For information on selecting the active page, refer to section 4.23 "SELECTING MEMORY PAGES" of this document. A0000:0->-----------<===========================================\ | |---------- | | | |---------- | | | | |---------- <==\=====| | | | | | | | ----------| | | | 64K | Page 0 ----------| | | | 256,000 Page 1 ----------| | | | Page 2 ---------- <==/=====/ Page 3 Video Data Format: The video data format is identical to IBM VGA mode 13h (320x200-256 color). Each pel is represented by 1 byte. Color Mapping: Color selection and palette changing is identical to VGA mode 13h. 4.35 640x480 - 256 COLORS (Mode 62h) Video Memory Configuration: This enhanced resolution mode uses a page memory system unique to this VGA board. The memory is organized into contiguous 64K blocks located at A0000H to AFFFFH. The VGA board must be equipped with 512K of RAM to support this mode. Mode 62h uses five 64K pages. For information on selecting the active page, refer to section 4.23 "SELECTING MEMORY PAGES" of this document. A0000:0 -> ---------- <=============================================\ | |--------- | | | |--------- | | | | |--------- | | | | | |--------- <=\ | ----------| | | | | | | Page 0 ---------| | | | 64K | Page 1 ---------| | | | 307,200 Page 2 ---------| | | | Page 3 --------- <=/====/ Page 4 Video Data Format: The video data format is identical to IBM VGA mode 13h (320x200-256 color). Each pel is represented by 1 byte. Color Mapping: Color selection and palette changing is identical to VGA mode 13h. 4.36 800x600 - 256 COLORS (Mode 63h) Video Memory Configuration: This enhanced resolution mode uses a page memory system unique to this VGA board. The memory is organized into contiguous 64K blocks located at A0000H to AFFFFH. The VGA board must be equipped with 512K of RAM to support this mode. Mode 63h uses eight 64K pages. For information on selecting the active page, refer to section 4.23 "SELECTING MEMORY PAGES" of this document. A0000:0 -> ----------<==============================================\ | |---------- | | | |---------- | | | | | \ | | | | | \ | ----------| | | \ | Page 0 ----------| | \ | Page 1 ---------- ---------- <=\ 480,000 Page 3 \ | | | | \ | | 64K | \ | | | | \ | | | | ---------- <=/=====/ Page 7 Video Data Format: The video data format is identical to IBM VGA mode 13h (320x200-256 color). Each pel is represented by 1 byte. Color Mapping: Color selection and palette changing is identical to VGA mode 13h. 4.37 800x600 - 256 COLORS (Mode 64h) Video Memory Configuration: This enhanced resolution mode uses a page memory system unique to this VGA board. The memory is organized into contiguous 64K blocks located at A0000H to AFFFFH. The VGA board must be equipped with 512K of RAM to support this mode. Mode 64h uses sixteen 64K pages. For information on selecting the active page, refer to section 4.23 "SELECTING MEMORY PAGES" of this document. A0000:0 -> ----------<==============================================\ | |---------- | | | |---------- | | | | | \ | | | | | \ | ----------| | | \ | Page 0 ----------| | \ | Page 1 ---------- ---------- <=\ 786,432 Page 3 \ | | | | \ | | 64K | \ | | | | \ | | | | ---------- <=/=====/ Page 15 Video Data Format: The video data format is identical to IBM VGA mode 13h (320x200-256 color). Each pel is represented by 1 byte. Color Mapping: Color selection and palette changing is identical to VGA mode 13h. 4.38 1024x768 - 16 COLORS (Mode 65h) Video Memory Organization: This enhanced resolution mode uses a page memory system unique to this VGA board. The memory is organized into contiguous 64K blocks located at A0000H to AFFFFH. The VGA board must be equipped with 512K of RAM to support this mode. Mode 65h uses eight 64K pages. For information on selecting the active page, refer to section 4.23 "SELECTING MEMORY PAGES" of this document. A0000:0 -> ---------- <=============================================\ | |---------- | | | |---------- | | | | | \ | | | | | \ | ----------| | | \ | Page 0 ----------| | \ | Page 1 ---------- ---------- <==\ 402,432 Page 2 \ | | | | \ | | | | \ | | 64K | \ | | | | ---------- <==/===/ Page 7 Video Data Format: The video data format is unique to this mode. Each pel requires 4 bits or half a byte. ____________________________________________ High Order | | | | | Pixel |____|____|____|____|____ ____ ____ ____ | H | H | H | H | L | L | L | L | |____|____|____|____|____|____|____|____| | | | | | |____|____|____|____|________ Low Order Pixel Color Mapping: This mode has a different memory organization than standard EGA mode 10h. If users want to use colors other than the standard 16 colors, users are required to re-program the external palettes (3C8h/3C9h). Re- programming the internal palettes (3C0h) will not work the same as it would in EGA mode 10h because the color mapping in mode 65h is different. It is not recommended to change the internal palettes at all for mode 65h. The following table shows the mapping of colors and external palettes. Palette registers available for re-programming are: Palette register Palette register default color color (low order pels) (high order pels) assignment value ---------------- ----------------- ------------- ----- 00h 00h Black 0h 01h 10h Blue 1h 02h 20h Green 2h 03h 30h Cyan 3h 04h 40h Red 4h 05h 50h Magenta 5h 06h 60h Brown 6h 07h 70h White 7h 08h 80h Dark Gray 8h 09h 90h Light Blue 9h 0Ah A0h Light Green Ah 0Bh B0h Light Cyan Bh 0Ch C0h Light Red Ch 0Dh D0h Light Magenta Dh 0Eh E0h Yellow Eh 0Fh F0h Bright White Fh For example, to change the default color assignment for palette register 4 from Red to Bright White, palette register 4 and 40h would need to be re-programmed with the values: Red Intensity = 3Fh Green Intensity = 3Fh Blue Intensity = 3Fh so that both the low order AND high order pels are affected. The only exception is palette register 0 (Black); re-programming this register will affect both the low order and high order pels. An Example: The following example uses a standard IBM EGA/VGA BIOS call. If more information is required, consult the IBM EGA/VGA programmers reference list included in this document. Example segment to re-program a palette register: mov ah,10h ;EGA/VGA Set Palette Register BIOS call mov al,10h mov bx,PALETTE_REG_LOW ;Palette register to be re-programmed ; for low order pels. mov ch,GREEN_INTENSITY ;Load new values mov cl,BLUE_INTENSITY mov dh,RED_INTENSITY int 10h mov ah,10h ;EGA/VGA Set Palette Register BIOS call mov al,10h mov bx,PALETTE_REG_HIGH ;Palette register to be re-programmed ; for high order pels. mov ch,GREEN_INTENSITY mov cl,BLUE_INTENSITY mov dh,RED_INTENSITY int 10h where: PALETTE_REG_LOW = low pel palette register (00,01,02,..,0F) PALETTE_REG_HIGH = high pel palette register (00,10,20,..,F0) GREEN_INTENSITY BLUE_INTENSITY = 6 bit intensity values for defining the default color RED_INTENSITY 4.39 1024x768 - 4 COLORS (Mode 67h) Video Memory Organization: The memory organization is identical to the IBM 16 color EGA and VGA modes. 256K of RAM is divided into 4 maps of 64k. The IBM EGA/VGA Map Mask Register is used to select the maps to be updated. A0000:0->/------\ | | /------\ | C0 | | | /------\ \------/ | C1 | | | /------\ <---+ Plane 0 \------/ | C0 | | | 49152 bytes/plane ^ Plane 1 \------/ | C1 | | | ^ Plane 2 \------/ <---+ | | ^ Plane 3 \---odd pels---/ | ^ | | \---even pels---/ Video Data Format: This mode uses a unique data format where 2 bits are required per pel. Plane 0 and 1 contain the data for odd numbered pels and Planes 2 and 3 contain the data for the even numbered pels. Color Mapping: This mode supports four palette selections. The palette or color set is selected by setting bits 0 & 1 of the IBM EGA/VGA Color Select Register. Color Values (C0, C1) Color set # C0=0,C1=0 C0=1,C1=0 C0=0,C1=1 C0=1,C1=1 0 black white grey bright white 1 black cyan red white 2 black green red yellow 3 black cyan magenta white Examples: The following examples use standard IBM EGA/VGA registers. If more information is required, consult the EGA/VGA programmers reference list included in this document. Segment example for selecting the active palette or color set: mov dx,03dah ;Load Input Status Register One ; wait: in al,dx ;Wait for vertical retrace bit to be set test al,8 ; (bit 3 = 1) jnz wait ;It is good practise to wait for the vertical ; retrace bit before directly modifying the ; palette registers mov ah,ARG ;Arg = color set # (0 to 3) mov cl,4 ;Multiply arg by 8 so that bits 4 & 5 of the shl ah,cl ; palette registers can be modified mov dx,03c0h ;Load Palette Control Register mov cx,16 ;16 Palette registers to be modified xor bl,bl ;Start from 0 ; repeat: ;Modify bits 4 & 5 of all 16 palette registers with mov al,bl ; Arg value (color set #) out dx,al ;Select palette register or al,ah out dx,al ;Write modified data to selected palette register loop repeat mov al,20h ;Restore internal registers access to palette data out dx,al ; bit 5 must be zero during palette data writing ; and one after data writing is complete Segment example for selecting Bit Planes to be modified during a memory write: mov dx,03c4h ;Load Sequencer Address Register mov al,2 ;Load index of Map Mask Register out dx,al ;Select Map Mask Register inc dl mov al,ARG ;Value to select which bit planes are to be ; modified during a memory write out dx,al ;Select EGA/VGA planes to be modified IBM EGA/VGA Map Mask Register (3C5h, index 2) organization: Bits: 0 Controls access to Bit Plane 0 1 Controls access to Bit Plane 1 2 Controls access to Bit Plane 2 3 Controls access to Bit Plane 3 4-7 Not used A bit value of 0 disables access to the corresponding Bit Plane and a bit value of 1 enables it. 4.4 SPECIAL NOTES 4.41 NOTE ON EXTENDED REGISTER ADDRESS Hard-coding this value is not recommended since it is programmable and may be changed in subsequent BIOS releases. The value of EXTENDED_REG should be retrieved from the BIOS at location C000:0010h. The 'mov dx, EXTENDED_REG statement in the page selecting segment can be replaced with code to load the value of EXTENDED_REG from its stored location. The registers that need to be saved will depend greatly on the particular application: push es ;save registers es and bx push bx mov ax,0c000h ;define storage location of EXTENDED_REG mov es,ax mov bx,10h mov dx,es:[bx] ;get the value of EXTENDED_REG from contents ;of the storage location C000:0010h pop bx ;restore registers es and bx pop es 4.42 NOTE ON DAC REGISTER PROGRAMMING In IBM VGA mode 13h (320x200 - 256 color), each color is controlled by a corresponding DAC register. There are a total of 256 18-bit DAC registers. Therefore, each DAC register can be assigned a color value from 0 (BLACK) to 262,143 (BRIGHT WHITE). The first 16 DAC registers have assigned color values that correspond to the 16 colors used in mode 12h (640x480 - 16 color). DAC register zero, which has an assigned color value of 0 (BLACK), also controls the color of the overscan border. This function is also supported in ATI modes 61, 62, 63, and 65h. On some analog monitors, a non-BLACK overscan border may cause line wrapping at either the top or bottom of the screen image due to the video bandwidth required. For this reason, it is not recommended to change the color value of this DAC register. 4.43 BIOS FUNCTION SUPPORT Many versions of the VGAWONDER do not support certain video BIOS function calls in some extended video modes due to EPROM space limitations. Programmers should assume that the following functions are not supported in the indicted modes: MODE # BIOS FUNCTION 61h, 62h, 63h, ah = 06h - Scroll active page up 65h, 67h ah = 07h - Scroll active page down ah = 09h - Read Character at Cursor ah = 0ch - Write Dot ah = 0dh - Read Dot ah = 0eh - Write TTX All extended modes have only one active page regardless of the amount of memory installed. 5.0 APPENDIX 5.1 LIST OF SUGGESTED REFERENCES TITLE: Programmer's Guide to the EGA/VGA * AUTHOR: George Sutty and Steve Blair PUBLISHER: Brady Books / Simon and Schuster, Inc. DATE: 1988 TITLE: Advanced Programmer's Guide to SuperVGAs * AUTHOR: George Sutty and Steve Blair PUBLISHER: Brady Books / Simon and Schuter, Inc. DATE: 1990 TITLE: Programmer's Guide to IBM PC and PS/2 Video Systems AUTHOR: Richard Wilton PUBLISHER: MicroSoft Press DATE: 1987 TITLE: Programmer's Guide to the EGA and VGA Cards AUTHOR: Richard F. Ferraro PUBLISHER: Addison - Wesley Publishing Co. DATE: July, 1988 TITLE: EGA/VGA A Programmer's Reference Guide AUTHOR: Bradley Dyck Kliewer PUBLISHER: McGraw Hill DATE: 1988 TITLE: Personal System/2 Model 50 and 60 Technical Reference AUTHOR: unknown PUBLISHER: IBM DATE: April, 1987 TITLE: Personal System/2 and Personal Computer BIOS Interface Technical Reference AUTHOR: unknown PUBLISHER: IBM DATE: April, 1987 TITLE: Programmer's Reference Manual for the VGAWONDER * AUTHOR: various PUBLISHER: ATI Technologies (order from Tech Support $40) DATE: 1990 * recommended TO OBTAIN A PRINT COPY OF THIS DOCUMENT ON YOUR SYSTEM PRINTER, ENTER THE FOLLOWING COMMAND AT THE DOS PROMPT: TYPE PROGINFO.DOC>PRN <rtn>