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** Programmer's Technical Reference for MSDOS and the IBM PC ** ┌─────────────────────────────┐ │ Shareware Version, 10/26/90 │ │ Please Register Your Copy │ └─────────────────────────────┘ Copyright (c) 1987, 1990 Dave Williams USA copyright TXG 392-616 ISBN 1-878830-02-3 (disk-based text) C H A P T E R T H R E E THE PC ROM BIOS - Interrupts 10h through 19h ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 10h Video I/O - services to handle video output │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0040h) The ROM video routines in the original PC BIOS are designed for use with the Color Graphics Adapter and incorporate code to test for the horizontal retrace before writing. The check is performed no matter what actual display adapter is installed. The ROM character table for the first 128 characters is located at 0FA6Eh in the PC. Int 01Fh can be used to point to a second table of 128 characters. CS, SS, DS, ES, BX, CX, DX are preserved during call. All others are destroyed. Function 00h Determine or Set Video State entry AH 00h set video mode AL display mode: CGA|PCjr|MDA|MCGA|EGA|VGA|8514 00h 40x25 B/W text CGA|PCjr| | |EGA| | 16 color 40x25, 320x400 graphics | | |MCGA| | | 16 color 40x25, 360x400 graphics | | | | |VGA| 16 color 01h 40x25 color text CGA|PCjr| | |EGA| | 02h 80x25 B/W text CGA|PCjr| | |EGA| | 16 color 80x25 640x400 graphics | | |MCGA| | | 16 color 80x25 720x400 graphics | | | |VGA| | 16 color 03h 80x25 color text CGA|PCjr| | |EGA|VGA| 4 color 04h 320x200 color graphics CGA|PCjr| | |EGA| | 4 tone gray 05h 320x200 B/W graphics CGA|PCjr| | |EGA| | 2 color 06h 640x200 B/W graphics CGA|PCjr| | |EGA| | monochrome 07h 80x25 monochrome text | |MDA| |EGA| | 16 color 08h 160x200 color graphics CGA|PCjr| | | | | 16 color 09h 320x200 color graphics |PCjr| | | |VGA| 4 color 0Ah 640x200 color graphics |PCjr| | | | | N/A 0Bh BIOS font load | | | |EGA|VGA| N/A 0Ch BIOS font load | | | |EGA|VGA| 16 color 0Dh 320x200 graphics | | | |EGA|VGA| 16 color 0Eh 640x200 graphics | | | |EGA|VGA| monochrome 0Fh 640x350 graphics | | | |EGA|VGA| 16 & 64 color 10h 640x350 color hi-res | | | |EGA|VGA| 2 color 11h 640x480 graphics | | |MCGA| |VGA| 16 color 12h 640x480 graphics | | | | |VGA| 256 color 13h 320x200 graphics | | |MCGA| |VGA|8514 14h-20h used by EGA and VGA graphics modes 18h 132x44 8x8 char mono | Tseng Labs EVA 19h 132x25 8x14 char mono | Tseng Labs EVA 1Ah 132x28 8x13 char mono | Tseng Labs EVA monochrome 21h Hercules Graphics, Graphics Page 1 monochrome 22h Hercules Graphics, Graphics Page 2 22h 132x44 | Tseng, Ahead 23h 132x25 | Tseng Labs EVA 132x25 | Ahead Systems EGA2001 132x25 | ATI EGA Wonder 24h 132x28 | Tseng Labs EVA 25h 80x60 640x480 | Tseng Labs EVA 16 color 640x480 | VEGA VGA 26h 80x60 | Tseng Labs EVA 80x60 640x480 | Ahead Systems EGA2001 16 color 27h 720x512 | VEGA VGA monochrome 132x25 | ATI EGA Wonder 28h unknown | VEGA VGA 16 color 29h 800x600 | VEGA VGA 256 color 2Dh 640x350 | VEGA VGA 256 color 2Eh 640x480 | VEGA VGA 256 color 2Fh 720x512 | VEGA VGA 256 color 30h 800x600 | VEGA VGA unknown | AT&T 6300 16 color 36h 960x720 | VEGA VGA 16 color 37h 1024x768 | VEGA VGA monochrome 132x44 | ATI EGA Wonder 2 color 40h 640x400 | AT&T 6300 80x43 | VEGA VGA 16 color 41h 640x200 | AT&T 6300 132x25 | VEGA VGA 16 color 42h 640x400 | AT&T 6300 132x43 | VEGA VGA 43h unsupported 640x200 of 640x400 viewport AT&T 6300 80x60 | VEGA VGA 44h disable VDC and DEB output | AT&T 6300 100x60 | VEGA VGA 48h 80x50 640x400 | AT&T 6300 4Dh 120x25 | VEGA VGA 4Eh 120x43 | VEGA VGA 4Fh 132x25 | VEGA VGA monochrome 50h 132x25 | Ahead Systems EGA2001 16 color 640x480 | Paradise EGA-480 monochrome 80x43 | VEGA VGA 640x480 mono? | Taxan 565 EGA 51h 80x30 | Paradise EGA-480 monochrome 132x25 | VEGA VGA 640x480 ? | ATI EGA Wonder monochrome 52h 132x44 | Ahead Systems EGA2001 monochrome 132x43 | VEGA VGA 752x410 ? | ATI EGA Wonder 53h 800x560 ? | ATI EGA Wonder 54h 132x43 | Paradise EGA-480 16 color 132x43 | Paradise VGA 16 color 132x43 | Paradise VGA on multisync 132x43 | Taxan 565 EGA 55h 132x25 | Paradise EGA-480 16 color 132x25 | Paradise VGA 16 color 132x25 | Paradise VGA on multisync 132x25 | Taxan 565 EGA 56h 132x43 | NSI Smart EGA+ 132x43 | Paradise VGA 132x43 | Paradise VGA on multisync monochrome 132x43 | Taxan 565 EGA 57h 132x25 | NSI Smart EGA+ 132x25 | Paradise VGA 132x25 | Paradise VGA on multisync monochrome 132x25 | Taxan 565 EGA 58h 100x75 800x600 16/256k | Paradise VGA 59h 100x75 800x600 | Paradise VGA 5Eh 640x400 | Paradise VGA,VEGA VGA 5Fh 640x480 | Paradise VGA 60h 80x? ?x400 | Corona/Cordata BIOS v4.10+ 752x410 | VEGA VGA 60h 400 line graphics+80 col text |(Corona/Cordata) 61h 400 line graphics | Corona/Cordata BIOS v4.10+ 720x540 | VEGA VGA 62h 800x600 | VEGA VGA 16 color 71h 100x35 800x600 | NSI Smart EGA+ 74h 640x400 graphics | Toshiba 3100 7Eh Special Mode Set | Paradise VGA (see below) BX horizontal dimension of the mode desired CX vertical dimension of the mode desired (both BX/CX in pixels for graphics modes, rows for text modes) DX number of colors of the mode desired (use 0 for monochrome modes) return BH 7Eh if successful 7Fh Special Function Set | Paradise VGA (see below) BH 00h Set VGA Operation 01h Set Non-VGA Operation 02h Query Mode Status return BL 0 if operating in VGA mode 1 if non-VGA mode. CH total video RAM size in 64k byte units CL video RAM used by the current mode 03h Lock Current Mode Allows current mode (VGA or non-VGA) to survive reboot. BH 0Ah,0Bh,0Ch,0Dh,0Eh,0Fh write paradise registers 0,1,2,3,4,5 (port 03CEh indexes A,B,C,D,E,F) BL value to set in the paradise register. BH 1Ah,1Bh,1Ch,1Dh,1Eh,1Fh read paradise registers 0,1,2,3,4,5 (port 03CEh indexes A,B,C,D,E,F) return BL value of the Paradise register BH 7Fh if successful. note Color modes (0,1,2,3,4,5,6) will set non-VGA CGA operation. Monochrome mode 7 will set non-VGA MDA/Hercules operation. 82h 80x25 B&W | AT&T VDC overlay mode * 83h 80x25 | AT&T VDC overlay mode * 86h 640x200 B&W | AT&T VDC overlay mode * C0h 640x400 2/prog pallet | AT&T VDC overlay mode * C4h disable output | AT&T VDC overlay mode * D0h 640x400 | DEC VAXmate AT&T mode unknown 640x225 | Z-100 unknown 640x400 | Z-100 note 1) If the high bit in AL is set, the display buffer is not cleared when a new mode is selected. This may be used to mix modes on the display; for example, characters of two difference sizes might be displayed 2) Modes 8-10 are available on the PCjr, Tandy 1000, and PS/2 3) IBM claims 100% software and hardware emulation of the CGA with the MCGA chipset. All registers may be read and written as CGA. All characters are double-scanned to give 80x25 with 400 line resolution. The attributes for setting border color may be set on MCGA, but the borders will remain the default color (they cannot actually be set) 4) The IBM Color Graphics Adapter (CGA) is too slow for the screen to be updated before the vertical retrace of the monitor is completed. If the video RAM is addressed directly, the screen will have "snow" or interference. IBM's default is to turn the adapter off when it is being updated, ie "flickering" when the display is scrolled. 5) The vertical retrace signal may be ignored when using the MCGA adapter. The MCGA will not generate snow when written to. There is no flicker with the MCGA. 6) The PCjr Video Gate Array uses a user-defined block of main system RAM from 4 to 32k in size instead of having dedicated memory for the display. Vertical retrace may be ignored when writing to the PCjr. There is no flicker with the PCjr display. 7) The Hercules Graphics Card has 750x348 resolution 8) The Hercules Graphics Card takes 64k beginning at B:000 (same as MDA) 9) The CGA, MCGA, and VGA adapters use hardware address B:800 10) The BIOS clears the screen when the mode is set or reset. 11) For AT&T VDC overlay modes, BL contains the DEB mode, which may be 06h, 40h, or 44h 12) Int 10 will take the shapes of the first 128 characters (00h-7Fh) from the table located in ROM at absolute address F000:FA6E. The EGA and VGA have hardware capability to change this. Function 01h Set Cursor Type - set the size of the cursor or turn it off entry AH 01h CH bit values: bits 0-4 top line for cursor in character cell bits 5-6 blink attribute 00 normal 01 invisible (no cursor) 10 slow (not used on original IBM PC) 11 fast CL bit values: bits 0-4 bottom line for cursor in character cell return none note 1) The ROM BIOS default cursors are: start end monochrome mode 07h: 11 12 text modes 00h-03h: 6 7 2) The blinking in text mode is caused by hardware and cannot be turned off, though some kludges can temporarily fake a nonblinking cursor 3) The cursor is automatically turned off in graphics mode 4) Another method of turning off the cursor in text mode is to position it to a nondisplayable address, such as (X,Y)=(0,25) 5) Buggy on EGA systems - BIOS remaps cursor shape in 43 line modes, but returns unmapped cursor shape Function 02h Set Cursor Position - reposition the cursor to (X,Y) entry AH 02h BH video page 00h graphics mode 03h modes 2 and 3 07h modes 0 and 1 DH row (Y=0-24) DL column (X=0-79 or 0-39) return none note 1) (0,0) is upper left corner of the screen Function 03h Read Cursor Position - return the position of the cursor entry AH 03h BH page number 00h in graphics modes 03h in modes 2 & 3 07h in modes 0 & 1 return CH top line for cursor (bits 4-0) CL bottom line for cursor (bits 4-0) DH row number (Y=0-24) DL column number (X=0-79 or 0-39) Function 04h Read Light Pen - fetch light pen information entry AH 04h return AH 00h light pen not triggered AH 01h light pen is triggered, values in resgisters BX pixel column (X=0-319 or 0-639) graphics mode CH raster line (Y=0-199) old graphics modes CX (EGA) raster line (0-nnn) new graphics modes DH row of current position (Y=0-24) text mode DL column of current position (X=0-79 or 0-39) text mode note Not supported on PS/2 Function 05h Select Active Page - set page number for services 6 and 7 entry AH 05h AL number of new active page 0-7 modes 00h and 01h (CGA) 0-3 modes 02h and 03h (CGA) 0-7 modes 02h and 03h (EGA) 0-7 mode 0Dh (EGA) 0-3 mode 0Eh (EGA) 0-1 mode 0Fh (EGA) 0-1 mode 10h (EGA) 0 set address of graphics bitmap buffer (modes 60h,61h) BX segment of buffer 0Fh get address of graphics bitmap buffer (modes 60h,61h) BX segment of buffer for PCjr only: AL 80h to read CRT/CPU page registers 81h to set CPU page register to value in BL 82h to set CRT page register to value in BH 83h to set both CPU and page registers (and Corona/Cordata BIOS v4.10+) BH CRT page number for subfunctions 82h and 83h BL CPU page register for subfunctions 81h and 83h return standard PC none PCjr if called with AH bit 7=1 then BH CRT page register (if AL >= 80h) BL CPU page register (if AL >= 80h) DX segment of graphics bitmap buffer (video modes 60h,61h; AL=0Fh) note 1) Mono adapter has only one display page 2) CGA has four 80x25 text pages or eight 40x25 text pages 3) A separate cursor is maintained for each display page 4) Switching between pages does not affect their contents 5) Higher page numbers indicate higher memory positions Function 06h Scroll Page Up - scroll up or clear a display "window" entry AH 06h AL number of lines blanked at bottom of page 0 = blank entire window BH attributes to be used on blank line CH row (Y) of upper left corner or window CL column (X) of upper left corner of window DH row (Y) of lower right corner of window DL column (X) of lower right corner of window return none note 1) Push BP before scrolling, pop after 2) If in CGA text mode, affects current page only Function 07h Scroll Page Down - scroll down or clear a display "window" entry AH 07h AL number of lines to be blanked at top of page 0 = blank entire window BH attributes to be used on blank line CH row (Y) of upper left corner or window CL column (X) of upper left corner of window DH row (Y) of lower right corner of window DL column (X) of lower right corner of window return none note 1) Push BP before scrolling, pop after 2) If in CGA text mode, affects current page only Function 08h Read Character Attribute - of character at current cursor pos. entry AH 08h BH display page number - text mode return AH character attribute - text mode AL ASCII code of character at current cursor position Function 09h Write Character and Attribute - at current cursor position entry AH 09h AL ASCII code of character to display BH display page number - text mode BL attribute/color of character CX number of characters to write return none note 1) CX should not exceed actual rows availible, or results may be erratic 2) Setting CX to zero will cause runaway 3) All values of AL result in some sort of display; the various control characters are not recognized as special and do not change the current cursor position 4) Does not change cursor position when called - the cursor must be advanced with int 10 function 0Ah. 5) If used to write characters in graphics mode with bit 7 of AH set to 1 the character will by XORed with the current display contents. 6) In graphics mode the bit patterns for ASCII character codes 80h-0FFh are obtained from a table. On the standard PC and AT, the location is at interrupt vector 01Fh (0000:007C). For ASCII characters 00h-07Fh, the table is at an address in ROM. On the PCjr the table is at interrupt vector 44h (0000:00110) and is in addressable RAM (may be replaced by the user) 7) All characters are displayed, including CR, LF, and BS Function 0Ah Write Character - display character(s) (use current attribute) entry AH 0Ah AL ASCII code of character to display BH display page - text mode BL color of character (graphics mode, PCjr only) CX number of times to write character return none note 1) CX should not exceed actual rows availible, or results may be erratic 2) All values of AL result in some sort of display; the various control characters are not recognized as special and do not change the current cursor position 3) If used to write characters in graphics mode with bit 7 of AH set to 1 the character will by XORed with the current display contents. 4) In graphics mode the bit patterns for ASCII character codes 80h-0FFh are obtained from a table. On the standard PC and AT, the location is at interrupt vector 01Fh (0000:007C). For ASCII characters 00h-07Fh, the table is at an address in ROM. On the PCjr the table is at interrupt vector 44h (0000:00110) and is in addressable RAM (may be replaced by the user) 5) In EGA in graphics modes, replication count in CX works correctly only if all characters written are contained on the same row 6) All characters are displayed, including CR, LF, and BS Function 0Bh Set Color Palette - set palette for graphics or text border entry AH 0Bh BH 00h select border (text mode) BL color 0-15, 16-31 for high-intensity characters BH 01h set graphics palette with value in BL (CGA) BL 0 green/red/yellow 1 cyan/magenta/white (EGA) (graphics modes) BH 0 BL has border color (0-15) & high intensity bkgr'd color (16-31) BH 1 BL contains palette being selected (0-1) return none note 1) Valid in CGA mode 04h, PCjr modes 06h, 08h-0Ah 2) Although the registers in the MCGA may be set as if to change the border, the MCGA will not display a border no matter what register settings are used. Function 0Ch Write Dot - plot one graphics pixel entry AH 0Ch AL dot color code (0/1 in mode 6, 0-3 in modes 4 and 5) (set bit 7 to XOR the dot with current color) 0-3 mode 04h, 05h 0-1 mode 06h BH page number (ignored if adapter supports only one page) CX column (X=0000h - 027Fh) (0 - 319 in modes 4,5,13, 0 - 639 in modes 6,14,15,16) DX row (Y=0000h - 00C7h) (0 - 199 CGA) return none note Video graphics modes 4-6 only Function 0Dh Read Dot - determine the color of one graphics pixel entry AH 0Dh CX column (X=0000h - 027Fh) (0-319 or 639) DX row (Y=0000h - 00C7h) (0-199) return AL color of dot note Only valid in graphics mode Function 0Eh Write TTY - write one character and update cursor. Also handles CR (0Dh), beep (07h), backspace (10h), and scrolling entry AH 0Eh AL ASCII code of character to be written BH page number (text) BL foreground color (video modes 6 & 7 only) (graphics) return none note 1) The ASCII codes for bell, backspace, carriage return, and linefeed are recognized and appropriate action taken. All other characters are written to the screen and the cursor is advanced to the next position 2) Text can be written to any CGA page regardless of current active page 3) Automatic linewrap and scrolling are provided through this function 4) This is the function used by the DOS CON console driver. 5) This function does not explicitly allow the use of attributes to the characters written. Attributes may be provided by first writing an ASCII 27h (blank) with the desired attributes using function 09h, then overwriting with the actual character using this function. While clumsy this allows use of the linewrap and scrolling services provided by this function Function 0Fh Return Current Video State - mode and size of the screen entry AH 0Fh return AH number of character columns on screen AL mode currently set (see AH=00h for display mode codes) BH current active display page note If mode was set with bit 7 set ("no blanking"), the returned mode will also have bit 7 set Function 10h Set Palette Registers (PCjr, Tandy 1000, EGA, MCGA, VGA) entry AH 10h AL 00h set individual palette register BH color value to store BL palette register to set (on MCGA, only BX = 0712h is supported) 01h set border color palette register BH color value to store 02h set all palette registers and overscan ES:DX pointer to 17-byte list bytes 0-15 values for palette regs. 0-15 byte 16 value for border color register 03h toggle blink/intensity bit (Jr, EGA, MCGA, VGA) BL 00h enable intensity 01h enable blink 04h unknown 05h unknown 06h unknown 07h read individual palette register (VGA) BL palette register number return BH palette register value 08h read overscan (order color) register (VGA) return BH value 09h read all palette registers and overscan register (VGA) ES:DX pointer to buffer address (17 bytes) 10h set individual video DAC color register (MCGA, VGA) BX register number CH new value for green (0-63) CL new value for blue (0-63) DH new value for red (0-63) 11h unknown 12h set block of video DAC color registers (MCGA, VGA) BX starting color register CX number of registers to set ES:DX table of 3*CX bytes where each 3 byte group represents one byte each of red, green and blue (0-63) 13h set video DAC color page (VGA) BH 00h select 4 blocks of 64 BH 01h select 16 blocks of 16 BL 00h select paging mode BL 01h select Page BH page number (00h to 03h) or (00h to 0Fh) (not valid in mode 13h) 14h unknown 15h read individual video DAC color register (MCGA, VGA) BL palette register number return DH red value CH green value CL blue value 16h unknown 17h read block of video DAC color registers (MCGA, VGA) BX starting palette register CX number of palette registers to read ES:DX buffer (3 * CX bytes in size) return CX number of red, green and blue triples in buffer 18h *UNDOCUMENTED* set PEL mask BL new PEL value 19h *UNDOCUMENTED* read PEL mask BL value read 1Ah read video DAC color-page state (VGA) return BL paging mode 0 four pages of 64 1 sixteen pages of 16 BH current page 1Bh perform gray-scale summing (MCGA, VGA) BX starting palette register CX number of registers to convert BH color value BL if AL=00h palette register to set (00h-0Fh) if AL=03h 0 to enable intensity 1 to enable blinking ES:DX if AL=02h pointer to 16-byte table of register values followed by the overscan value: bytes 0-15 values for palette registers 0-15 byte 16 value for border register return none note DAC is Digital to Analog Convertor circuit in MCGA/VGA chips Function 11h Character Generator Routine (EGA and after) entry AH 11h The following functions will cause a mode set, completely resetting the video environment, but without clearing the video buffer. AL 00h, 10h load user-specified patterns BH number of bytes per character pattern BL block to load in map 2 CX count of patterns to store DX character offset into map 2 block ES:BP pointer to user table 01h, 11h load ROM monochrome patterns (8 by 14) BL block to load 02h, 12h load ROM 8 by 8 double-dot patterns BL block to load 03h set block specifier BL block specifier (EGA/MCGA) bits 0,1 = block selected by chars with attribute bit 3 = 0 bits 2,3 = block selected by chars with attribute bit 3 = 1 (VGA) bits 0,1,4 = block selected by attribute bit 3 = 0 bits 2,3,5 = block selected by attribute bit 3 = 1 04h,14h load 8x16 text character set (MCGA, VGA) The routines called with AL=1x are designed to be called only immediately after a mode set and are similar to the routines called with AL=0x, except that: Page 0 must be active. Bytes/character is recalculated. Max character rows is recalculated. CRT buffer length is recalculated. CRTC registers are reprogrammed as follows: reg09h bytes/char-1; max scan line (mode 7 only) reg0Ah bytes/char-2; cursor start reg0Bh 0 ; cursor end reg12h ((rows+1)*(bytes/char))-1 ; vertical display end reg14h bytes/char ; underline loc (* BUG: should be 1 less *) The following functions are meant to be called only after a mode set: 20h user 8 by 8 graphics characters (int 1Fh) ES:BP pointer to user table 21h user graphics characters ES:BP pointer to user table CX bytes per character BL row specifier 0 user set DL number of rows 1 14 rows 2 25 rows 3 43 rows 22h ROM 8 by 14 set BL row specifier 23h ROM 8 by 8 double dot BL row specifier 24h load 8x16 graphics characters (MCGA, VGA) BL row specifier 30h Get Font Information (EGA, MCGA, VGA) BH pointer specifier 0 int 1Fh pointer 1 int 44h pointer 2 ROM 8 by 14 character font pointer 3 ROM 8 by 8 double dot font pointer 4 ROM 8 by 8 DD font (top half) 5 ROM text alternate (9 by 14) pointer return ES:BP specified pointer value CX bytes/character DL character rows on screen Function 12h Alternate Select (EGA and after) entry AH 12h BL 10h return EGA information return BH 00h if color mode is in effect (3Dx) 01h if mono mode is in effect (3Dx) BL 00h if 64k EGA memory 01h if 128k EGA memory 02h if 192k EGA memory 03h if 256k EGA memory CH feature bits CL switch settings 20h select alternate print screen routine 30h select vertical resolution for text modes (VGA) AL 00h 200 scan lines 01h 350 scan lines 02h 400 scan lines return AL 12h if function supported 31h enable/disable default palette loading (MCGA, VGA) AL 00h enable default palette loading 01h disable default palette loading return AL 12h if function was supported 32h enable/disable video addressing (MCGA, VGA) AL 00h enable video 01h disable video return AL 12h if function was supported 33h enable/disable default gray scale summing (MCGA, VGA) AL 00h enable gray scale summing 01h disable gray scale summing return AL 12h if function was supported 34h enable/disable text cursor emulation (VGA) AL 00h enable cursor emulation 01h disable cursor emulation return AL 12h if function was supported 35h display-switch interface (PS/2) AL 00h initial adapter video off 01h initial planar video on 02h switch active video off 03h switch inactive video on 80h *undocumented* set system board video active flag ES:DX buffer (128 byte save area if AL = 0, 2 or 3) return AL 12h if function was supported 36h video refresh control (VGA) AL 00h enable refresh 01h disable refresh return AL 12h if function supported BX 5500h (used by ATI and TAXAN) BX 5502h (used by ATI and TAXAN) Function 13h Enhanced String Write (AT, XT/286, PS/2) entry AH 13h AL 00h Write String, Don't Move Cursor 01h Write String, Move Cursor 02h Write String of Alternating Characters and Attributes; Don't Move Cursor bit 0: set in order to move cursor after write bit 1: set if string contains alternating chars and attributes 03h Write String of Alternating Characters and Attributes; Move Cursor bit 0: set in order to move cursor after write bit 1: set if string contains alternating characters and attributes BH display page number BL attribute if AL bit 1 clear CX length of string DH row of starting cursor position DL column of starting cursor position ES:BP pointer to start of string return none note Recognizes CR, LF, BS, and bell Function 14h Load LCD Character Font (Convertible) entry AH 14h AL 00h load user specified font BH number of bytes per character BL 00h load main font (block 0) 01h load alternate font (block 1) CX number of characters to store DX character offset into RAM font area ES:DI pointer to character font AL 01h load system ROM default font BL 00h load main font (block 0) 01h load alternate font (block 1) AL 02h set mapping of LCD high intensity attribute BL 00h ignore high intensity attribute 01h map high intensity to underscore 02h map high intensity to reverse video 03h map high intensity to seleected alternate font return unknown Function 15h Return Physical Display Parameters (Convertible) entry AH 15h return AX Alternate display adapter type ES:DI pointer to parameter table: word # information 01h monitor model number 02h vertical pixels per meter 03h horizontal pixels per meter 04h total number of vertical pixels 05h total number of horizontal pixels 06h horizontal pixel separation in micrometers 07h vertical pixel separation in micrometers Function 1Ah Display Combination Code (MCGA, VGA) Using the compatibility BIOS of the PS/2 Models 50, 60, 80 there is a way to determine which video controller and attached display are on the system. The Display Combination Code (DCC) is a Video BIOS function that provides the capability. entry AH 1Ah AL 00h read display combination code 01h write display combination code return AL 1Ah indicates Compatibility BIOS is supported, any other value is invalid BH Display Combination Code (DCC) 00h no display 01h IBM monochrome adapter and display 02h IBM color/graphics monitor adapter w/color display 03h reserved 04h IBM EGA, color display 05h IBM EGA, monochrome display 06h IBM PGA, color display 07h VGA, analog monochrome display 08h VGA, analog color display 09h reserved 0Ah MCGA, digital color display 0Bh MCGA, analog monochrome display 0Ch MCGA, analog color display 0FFh unknown display type BL active display device code note This function may be used to test for VGA, since it is not supported in earlier adapters. If AL is still 1Ah when the call completes, a VGA compatible adapter is present. Function 1Bh Functionality/State Information (MCGA, VGA) entry AH 1Bh BX implementation type 0000h return funtionality/state information ES:DI pointer to 64 byte buffer return AL 1Bh if function supported ES:DI buffer filled 00h address of functionality table 01h unknown 02h unknown 03h unknown 04h current video mode 05h number of columns 06h unknown 07h length of regen buffer in bytes 09h starting address of regen buffer 0Bh cursor position for page 0 0Dh cursor position for page 1 0Fh cursor position for page 2 11h cursor position for page 3 13h cursor position for page 4 15h cursor position for page 5 17h cursor position for page 6 19h cursor position for page 7 1Bh cursor type 1Dh active display page 1Eh CRTC port address 20h current setting of register (3?8) 21h current setting of register (3?9) 22h number of rows 23h bytes/character 25h DCC of active display 26h DCC of alternate display 27h number of colors supported in current mode 29h number of pages supported in current mode 2Ah number of scan lines active (0,1,2,3) = (200,350,400,480) 2Bh primary character block 2Ch secondary character block 2Dh miscellaneous flags byte bit 0 all modes on all displays on 1 gray summing on 2 monochrome display attached 3 default palette loading disabled 4 cursor emulation enabled 5 0=intensity; 1=blinking 6 reserved 7 reserved 2Eh to 30h reserved 31h video memory available 00h=64K, 01h=128K, 02h=192K, 03h=256K 32h save pointer state flags byte bit 0 512 character set active 1 dynamic save area present 2 alphanumeric font override active 3 graphics font override active 4 palette override active 5 DCC override active 6 reserved 7 reserved 33h to 3Fh reserved note State Functionality Table format (16 bytes) 00h modes supported #1 bit 0 to bit 7 = 1 modes 0,1,2,3,4,5,6 supported 01h modes supported #2 bit 0 to bit 7 = 1 modes 8,9,A,B,C,D,E,F supported 02h modes supported #3 bit 0 to bit 3 = 1 modes 10,11,12,13 supported bit 4 to bit 7 reserved 03h to 06h reserved 07h scan lines supported bit 0 to bit 2 = 1 if scan lines 200,350,400 supported 08h total number of character blocks available in text modes 09h maximum number of active character blocks in text modes 0Ah miscellaneous function flags #1 bit 0 all modes on all displays function supported 1 gray summing function supported 2 character font loading function supported 3 default palette loading enable/disable supported 4 cursor emulation function supported 5 EGA palette present 6 color palette present 7 color paging function supported 0Bh miscellaneous function flags #2 bit 0 light pen supported 1 save/restore state function 1Ch supported 2 intensity blinking function supported 3 Display Combination Code supported 4-7 reserved 0Ch to 0Dh reserved 0Eh Save pointer function flags bit 0 512 character set supported 1 dynamic save area supported 2 text font override supported 3 graphics font override supported 4 palette override supported 5 DCC extension supported 6 reserved 7 reserved 0Fh reserved Function 1Ch Save/Restore Video State (VGA) entry AH 1Ch AL 00h return state buffer size 01h save video state ES:BX buffer address 02h restore video state ES:BX buffer address of previously saved state CX requested states bit 0 video hardware 1 BIOS data areas 2 color registers and DAC state 3-15 reserved return AL 1Ch if function supported BX number of 64 byte blocks needed (function 00h) note VGA only Function 40h Set Graphics Mode (Hercules Graphics Card Plus) entry AH 40h return unknown Function 41h Set Text Mode (Hercules Graphics Card Plus) entry AH 41h return unknown Function 42h Clear Current Page (Hercules Graphics Card Plus) entry AH 42h return unknown Function 43h Select Drawing Page (Hercules Graphics Card Plus) entry AH 43h AL page number (0,1) return unknown Function 44h Select Drawing Function (Hercules Graphics Card Plus) entry AH 44h AL 0 clear pixels 1 set pixels 2 invert pixels return unknown Function 45h Select Page to Display (Hercules Graphics Card Plus) entry AH 45h AL page number (0,1) return unknown Function 46h Draw One Pixel (Hercules Graphics Card Plus) entry AH 46h DI x (0-720) BP y (0-347) return unknown note Function 44h determines operation and function 43h which page to use. Function 47h Find Pixel Value (Hercules Graphics Card Plus) entry AH 47h DI x (0-720) BP y (0-347) return AL 0 pixel clear 1 pixel set note Function 43h specifies page that is used. Function 48h Move to Point (Hercules Graphics Card Plus) entry AH 48h DI x (0-720) BP y (0-347) return unknown Function 49h Draw to Point (Hercules Graphics Card Plus) entry AH 49h DI x (0-720) BP y (0-347) return unknown note Function 48h or 49h specify first point, 44h operation and 43h page to use. Function 4Ah Block Fill (Hercules Graphics Card Plus) entry AH 4Ah return unknown Function 4Bh Display Character (Hercules Graphics Card Plus) entry AH 4Bh AL ASCII code for character to display DI x (0-720) BP y (0-347) return unknown note Unlike the other BIOS character functions character position is specified in pixels rather than rows and columns. Function 4Ch Draw Arc (Hercules Graphics Card Plus) entry AH 4Ch return unknown Function 4Dh Draw Circle (Hercules Graphics Card Plus) entry AH 4Dh return unknown Function 4Eh Fill Area (Hercules Graphics Card Plus) entry AH 4Eh return unknown Function 6Ah Direct Graphics Interface Standard (DGIS) entry AH 6Ah AL 00h Inquire Available Devices BX 0 CX 0 DX buffer length (may be 0) ES:DI address of buffer return BX number of bytes stored in buffer CX bytes req'd for all descriptions (0 if no DGIS) note Buffer contains descriptions and addresses of DGIS- compatible display(s) and printer(s) 01h Redirect Character Output CX 0 ES:DI address of device to send INT 10 output to return CX 0 output could not be redirected else INT 10h output now routed to requested display 02h Inquire int 10 Output Device ES:DI 0:0 return ES:DI 0:0 if current display is non-DGIS else address of the current DGIS INT 10 display Function 6Fh Set Video Mode (VEGA Extended EGA/VGA) entry AH 6F AL 05h BL mode| (graphics mode if graphics resolution listed) | text |pixel| graphic|color|disp|scrn| system | resol|box |resoltn | |page|addr| 62h 800x600 16 VEGA Extended EGA 65h 1024x768 16 VEGA Extended EGA 66h 640x400 256 VEGA Extended VGA 67h 640x480 256 VEGA Extended VGA 68h 720x540 256 VEGA Extended VGA 69h 800x600 256 VEGA Extended VGA Function 70h Get Video RAM Address (Tandy 1000) entry AH 70h return AX segment addresses of the following BX offset address of green plane CX segment address of green plane DX segment address of red/blue plane note (red offset = 0, blue offset = 4000) Function 71h Get INCRAM Addresses (Tandy 1000) entry AH 71h return AX segment address of the following BX segment address of INCRAM CX offset address of INCRAM Function 72h Scroll Screen Right (Tandy 1000) entry AH 72h AL number of columns blanked at left of page 00h blank window BH attributes to be used on blank columns CH,CL row, column address of upper left corner DH,DL row, column address of lower right corner Function 73h Scroll Screen Left (Tandy 1000) entry AH 73h AL number of columns blanked at right of page 00h blank window BH attributes to be used on blank columns CH,CL row, column address of upper left corner DH,DL row, column address of lower right corner Function 80h DESQview - Set (something) entry AH 80h DX 4456h ('DV') ES:DI pointer to FAR subroutine to be called on? return DS segment of DESQview data structure for video buffer note 1) This function is probably meant for internal use only, due to the magic value required in DX 2) The subroutine seems to be called when the DESQview menu is accessed on entry, AL = 03h or 04h Function 81h DESQview video - Get something? entry AH 81h DX 4456h ('DV') return ES segment of DESQview data structure for video buffer byte ES:[0] = current window number note This function is probably meant for internal use only, due to the magic value required in DX Function 82h DESQview - Get Current Window Info entry AH 82h DX 4456h ('DV') return AH unknown AL current window number BH unknown BL direct screen writes 0 program does not do direct writes 1 program does direct writes, so shadow buffer not usable CH unknown CL current video mode DS segment in DESQview for data structure in DV 2.00, byte DS:[0] = window number word DS:[1] = segment of other data structure word DS:[3] = segment of window's object handle ES segment of DESQview data structure for video buffer note This function is probably meant for internal use only, due to the magic value required in DX Function 0F0h Microsoft Mouse driver EGA support - Read One Register entry AH 0F0h BL register number DX group index (pointer/data chips) 00h CRT Controller (25 reg) 3B4h mono, 3D4h color 08h sequencer (5 registers) 3C4h 10h graphics controller (9 registers) 3CEh 18h attribute controller (20 registers) 3C0h (single registers) 20h miscellaneous output register 3C2h 28h feature control register (3BAh mono, 3DAh color 30h graphics 1 position register 3CCh 38h graphics 2 position register 3CAh return BL data Function 0F1h Microsoft Mouse driver EGA support - Write One Register entry AH 0F1h DX group index (see function F0h) BL register number BH value to write return BL data Function 0F2h Microsoft Mouse driver EGA support - Read Register Range entry AH 0F2h CH starting register number CL number of registers (>1) DX group index 00h CRTC (3B4h mono modes, 3D4h color modes) 08h sequencer 3C4h 10h graphics controller 3CEh 18h attribute controller 3C0h ES:BX pointer to buffer, CL bytes Function 0F3h Microsoft Mouse driver EGA support - Write Register Range entry AH 0F3h CH starting register CL number of registers (>1) DX group index 00h CRTC (3B4h mono modes, 3D4h color modes) 08h sequencer 3C4h 10h graphics controller 3CEh 18h attribute controller 3C0h ES:BX pointer to buffer, CL bytes Function 0F4h Microsoft Mouse driver EGA support - Read Register Set entry AH 0F4h CX number of registers (>1) ES:BX pointer to table of records in this format: bytes 1-2 group index (pointer/data chips) 00h CRTC (3B4h mono modes, 3D4h color modes) 08h sequencer 3C4h 10h graphics controller 3CEh 18h attribute controller 3C0h (single registers) 20h miscellaneous output register 3C2h 28h feature control register (3BAh mono modes, 3DAh color) 30h graphics 1 position register 3CCh 38h graphics 2 position register 3CAh byte 3 register number (0 for single registers) byte 4 register value Function 0F5h Microsoft Mouse driver EGA support - Read Register Set entry AH 0F5h CX number of registers (>1) ES:BX pointer to table of records in this format: bytes 1-2 group index (pointer/data chips) 00h CRTC (3B4h mono modes, 3D4h color modes) 08h sequencer 3C4h 10h graphics controller 3CEh 18h attribute controller 3C0h (single registers) 20h miscellaneous output register 3C2h 28h feature control register (3BAh mono modes, 3DAh color) 30h graphics 1 position register 3CCh 38h graphics 2 position register 3CAh byte 3 register number (0 for single registers) byte 4 register value Function 0F6h Microsoft Mouse driver EGA support Revert to Default Registers entry AH 0F6h return unknown Function 0F7h Microsoft Mouse driver EGA support Define Default Register Table entry AH 0F7h DX port number ES:BX address of table of one byte entries, one byte to be written to each register (pointer/data chips) 00h CRTC (3B4h mono modes, 3D4h color modes) 08h sequencer 3C4h 10h graphics controller 3CEh 18h attribute controller 3C0h (single registers) 20h miscellaneous output register 3C2h 28h feature control register (3BAh mono, 3DAh color) 30h graphics 1 position register 3CCh 38h graphics 2 position register 3CAh Function 0FAh Microsoft Mouse driver EGA support - Interrogate Driver entry AH 0FAh BX 00h return BX 00h if mouse driver not present ES:BX pointer to EGA Register Interface version number, if present: byte 1 major release number byte 2 minor release number Function 0FEh Get Alternate Screen Buffer Address (text mode only) (Topview/DesQview/Taskview) entry AH 0FEh ES:DI segment:offset of assumed video buffer return: ES:DI segment:offset of actual video buffer note 1) This alternate video buffer can be written to directly, in the same manner as writing to B:000 or B:800. The MT program will manage the actual display. 2) There is no need to synchronize vertical retrace when writing to the alternate buffer; this is managed by the MT program 3) If TopView or DESQview is not running, ES:DI is returned unchanged. 4) TopView requires that function 0FFh be called every time you write into the buffer to tell TopView that something changed Function 0FFh Update Real Display (text mode only) (TopView) Update Video Buffer (Topview/DesQview/Taskview) entry AH 0FFh CX number of sequential characters that have been modified DI offset of first character that has been modified ES segment of video buffer return unknown note 1) DesQview supports this call, but does not require it 2) Avoid CX=0 ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 11h Equipment Check │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0044h) fetch a code describing active peripherals. entry AH 11h return AX Equipment listing word Bits are: 0 number of floppy drives 0 no drives 1 bootable (IPL) diskette drive installed 1 math chip 0 no math coprocessor (80x87) present 1 math coprocessor (80x87) present (PS/2) 2 0 mouse not installed 1 mouse installed (PC) 2,3 system board RAM 0,0 16k (PC-0, PC-1) 1,1 64k (PC-2, XT) note 1) not commonly used. Set both bits to 1 2) both bits always 1 in AT 4,5 initial video mode 0,0 no video installed (use with dumb terminal) 0,1 40x25 color (CGA) 1,0 80x25 color (CGA, EGA, PGA, MCGA, VGA) 1,1 80x25 monochrome (MDA or Hercules, most super- hires mono systems) 6,7 number of diskette drives (only if bit 0 1) 0,0 1 drives 0,1 2 drives 1,0 3 drives 1,1 4 drives 8 0 DMA present 1 no DMA (PCjr, some Tandy 1000s, 1400LT) 9,A,B number of RS232 serial ports (0-3) 0,0,0 none 0,0,1 1 0,1,0 2 0,1,1 3 1,0,0 4 C 0 no game I/O attached 1 game I/O attached (default for PCjr) D serial accessory installation 0 no serial accessories installed 1 Convertible - internal modem installed 1 PCjr - serial printer attached E,F number of parallel printers 0,0 none 0,1 one (LPT1, PRN) 1,0 two (LPT2) 1,1 three (LPT3) note Models before PS/2 would allow a fourth parallel printer. Remapping of the BIOS in the PS/2s does not allow the use of LPT4. ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 12h Memory Size │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0048h) get system memory return AX number of contiguous 1K RAM blocks note 1) This service does not depend on the setting of the motherboard switches 2) This is the same value stored in absolute address 04:13h ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 13h Disk I/O - access the disk drives (floppy and hard disk) │ └─────────────────────────────────────────────────────────────────────────────┘ (0:004Ch) does not try rereading disk if an error is returned Function 00h Reset - reset the disk controller chip entry AH 00h DL drive (if bit 7 is set both hard disks and floppy disks reset) return AH status note 1) Forces controller chip to recalibrate read/write heads 2) Some systems (Sanyo 55x) this resets all drives Function 01h Get Status of disk system entry AH 01h DL drive (hard disk if bit 7 set) return AL status of most recent operation 00h successful completion 01h bad command 02h address mark not found 03h tried to write on write-protected disk 04h sector not found 05h reset failed (hard disk) 06h diskette removed or changed 07h bad parameter table (hard disk) 08h DMA overrun 09h attempt to DMA across 64K boundary 0Ah bad sector detected (hard disk) 0Bh bad track detected (hard disk) 0Ch unsupported track 0Dh invalid number of sectors on format (hard disk) 0Eh control data address mark detected (hard disk) 0Fh DMA arbitration error (hard disk) 10h bad CRC/EEC on read 11h data ECC corrected 20h controller failure 40h seek failed 80h timeout 0AAh drive not ready (hard disk) 0BBh undefined error (hard disk) 0CCh write fault (hard disk) 0E0h status error (hard disk) 0FFh sense operation failed (hard disk) Function 02h Read Sectors - read one or more sectors from diskette entry AH 02h AL number of sectors to read BX address of buffer (ES=segment) CH track number (0-39 or 0-79 for floppies) (for hard disk, bits 8,9 in high bits of CL) CL sector number (1 to 18, not value checked) DH head number (0 or 1) DL drive (0=A, 1=B, etc.) (bit 7=0) (drive 0-7) ES:BX address to store/fetch data (buffer to fill) [0000:0078] dword pointer to diskette parms return CF clear (0) for successful set (1) failure AH status (00h, 02h, 03h, 04h, 08h, 09h, 10h, 0Ah, 20h, 40h, 80h) AL number of sectors transferred note 1) Number of sectors begins with 1, not 0 2) Trying to read zero sectors is considered a programming error; results are not defined Function 03h Write Sectors - write from memory to disk entry AH 03h AL number of sectors to write (1-8) CH track number (for hard disk, bits 8,9 in high bits of CL) CL beginning sector number (if hard disk, high two bits are high bits of track #) DH head number DL drive number (0-7) ES:BX address of buffer for data return CF set if error AH status (see above) AL number of sectors written note 1) Number of sectors begins with 1, not 0 2) Trying to write zero sectors is considered a programming error; results are not defined Function 04h Verify - verify that a write operation was successful entry AH 04h AL number of sectors to verify (1-8) CH track number (for hard disk, bits 8,9 in high bits of CL) CL beginning sector number DH head number DL drive number (0-7) return CF set on error AH status (see above) AL number of sectors verified Function 05h Format Track - write sector ID bytes for 1 track entry AH 05h AL number of sectors to create on this track CH track (or cylinder) number CL sector number DH head number (0, 1) DL drive number (0-3) ES:BX pointer to 4-byte address field (C-H-R-N) byte 1 = (C) cylinder or track byte 2 = (H) head byte 3 = (R) sector byte 4 = (N) bytes/sector (0 = 128, 1 = 256, 2 = 512, 3 = 1024) return CF set if error occurred AH status code (see above) note Not valid for ESDI hard disks on PS/2 Function 06h Hard Disk - format track and set bad sector flags (PC2, PC-XT, and Portable) entry AH 06h AL interleave value (XT only) CH cylinder number (bits 8,9 in high bits of CL) CL sector number DH head DL drive ES:BX 512 byte format buffer the first 2*(sectors/track) bytes contain f,n for each sector f 00Fh for good sector 80h for bad sector n sector number return AH status code Function 07h Hard Disk - format the drive starting at the desired track (PC2, PC-XT and Portable) entry AH 07h AL interleave value (XT only) (01h-10h) CH cylinder number (bits 8,9 in high bits of CL) (00h-03FFh) CL sector number DH head number (0-7) DL drive number (80h-87h, 80h=C, 81h=D,...) ES:BX format buffer, size = 512 bytes the first 2*(sectors/track) bytes contain f,n for each sector f=00h for good sector 80h for bad sector n=sector number return AH status code (see above) note Award AT BIOS routines are extended to handle more than 1024 cylinders. AL number of sectors CH cylinder numberm low 8 bits CL sector number bits 0-5, bits 6-7 are high 2 cylinder bits DH head number (bits 0-5) bits 6-7 are extended high cyls (>1024) DL drive number (0-1 for diskette, 80h-81h for hard disk) ES:BX transfer address Function 08h Read Drive Parameters (XT, CONV, AT, XT/286, PS/2) entry AH 08h DL drive number (0-2) return CF set on error AH status code (see above) BL drive type (see AH=17h below) (AT/PS2 floppies only) CH maximum useable value for cylinder number CL maximum useable value for sector number or cylinder number DH maximum usable value for head number DL number of consecutive acknowledging drives (0-2) ES:DI drive parameter table Function 09h Initialize Two Fixed Disk Base Tables (XT, AT, XT/286, PS/2) (install nonstandard drive) entry AH 09h return CF set on error AH status code (see above) data block definitions: +0 maximum number of cylinders (dw) +2 maximum number of heads (db) +3 starting reduced write current cylinder (dw - XT only) +5 starting write precomp cylinder (dw) +7 maximum ECC data burst length (db - XT only) +8 control byte: Bits 0,1,2 ─ drive option 3,4,5 - always zero 6 - disable ECC retries 7 - disable access retries note 1) Int 41h points to table for drive 0 2) Int 46h points to table for drive 1 3) 41h used by XT, 41h and 46h used by AT Function 0Ah Read Long (Hard disk) (XT, AT, XT/286, PS/2) entry AH 0Ah CH cylinder number (bits 8,9 in high bits of CL) CL sector number DL drive ID DH head number ES:BX pointer to buffer to fill return CF set on error AH status code (see above) AL number of sectors actually transferred note 1) A "long" sector includes a 4 byte EEC (Extended Error Correction) code 2) Used for diagnostics only on PS/2 systems Function 0Bh Write Long (XT, AT, XT/286, PS/2) entry AH 0Bh CH cylinder (bits 8,9 in high bits of CL) CL sector number DH head number DL drive ID ES:BX pointer to buffer containing data return CF set on error AH status code (see above) AL number of sectors actually transferred note 1) A "long" sector includes a 4 byte EEC (Extended Error Correction) code 2) Used for diagnostics only on PS/2 systems Function 0Ch Seek To Cylinder (except PC, PCjr) entry AH 0Ch CH cylinder number (bits 8,9 in high bits of CL) DH head number DL drive ID return CF set on error AH status code (see above) note 1) Positions heads over a particular cylinder Function 0Dh Alternate Disk Reset (except PC, PCjr) entry AH 0Dh DL drive ID return CF set on error AH status code (see above) note Not for PS/2 ESDI hard disks Function 0Eh Read Sector Buffer (XT, Portable PS/2) entry AH 0Eh AL number of sectors CH cylinder (bits 8,9 in top two bits of CL) CL sector number DH head number DL drive number ES:BX pointer to buffer return CF set on error AH status code (see above) AL number of sectors actually transferred note 1) Transfers controller's sector buffer. No data is read from the drive 2) Used for diagnostics only on PS/2 systems Function 0Fh Write sector buffer (XT, Portable) entry AH 0Fh AL number of sectors CH cylinder (bits 8,9 in top two bits of CL) CL sector number DH head number DL drive number ES:BX pointer to buffer return CF set if error AH status code AL number of sectors actually transferred note 1) Should be called before formatting to initialize the controller's sector buffer. 2) Used for diagnostics only on PS/2 systems Function 10h Test For Drive Ready entry AH 10h DL drive ID return CF set on error AH status code (see above) Function 11h Recalibrate Drive entry AH 11h DL drive ID return CF set on error AH status code (see above) Function 12h Controller RAM Diagnostic (XT, Portable, PS/2) entry AH 12h return CF set on error AH status code (see AH=1 above) note Used for diagnostics only on PS/2 systems Function 13h Drive Diagnostic (XT, Portable) entry AH 13h return CF set on error AH status code (see above) note Used for diagnostics only on PS/2 systems Function 14h Controller Internal Diagnostic (AT, XT/286) entry AH 14h return CF set on error AH status code (see above) note 1) OEM is Western Digital 1003-WA2 hard/floppy combination controller in AT and XT/286. 2) Used for diagnostics only in PS/2 systems Function 15h Get Disk Type (except PC and XT) entry AH 15h DL drive ID return AH disk type 00h no drive is present 01h diskette, no change detection present 02h diskette, change detection present 03h fixed disk CX:DX number of 512-byte sectors when AH = 03h Function 16h Change of Disk Status (diskette) (except PC and XT) entry AH 16h return AH disk change status 00h no disk change 01h disk changed DL drive that had disk change Function 17h Set Disk Type for Format (diskette) (except PC and XT) entry AH 17h AL 00h no disk 01h 360kb diskette in 360Kb drive 02h 360kb diskette in 1.2M drive 03h 1.2M diskette in 1.2M drive 04h 720kb diskette in 720Kb drive DL drive number return AH status of operation note This function is probably enhanced for the PS/2 series to detect 1.44 in 1.44 and 720k in 1.44. Function 18h Set Media Type For Format (diskette) (AT, XT/286, PS/2) entry AH 18h CH lower 8 bits of number of tracks CL high 2 bits of number of tracks (6,7) sectors per track (bits 0-5) DL drive number return AH 00h if requested combination supported 01h if function not available 0Ch if not suppported or drive type unknown 80h if there is no media in the drive ES:DI pointer to 11-byte parameter table Function 19h Park Hard Disk Heads (XT/286, PS/2) entry AH 19h DL drive return CF set on error AH error code Function 1Ah ESDI Hard Disk - Format (PS/2) entry AH 1Ah AL defect table count CL format modifiers bits 0 ignore primary defect map 1 ignore secondary defect map 2 update secondary defect map 3 perform surface analysis 4 generate periodic interrupt DL drive ES:BX pointer to defect table return CF set on error AH status (see AH=1 above) note If periodic interrupt selected, int 15h/AH=0Fh is called after each cylinder is formatted ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 14h Initialize and Access Serial Port For Int 14 │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0050h) the following status is defined: serial status byte: bits 0 delta clear to send 1 delta data set ready 2 trailing edge ring detector 3 delta receive line signal detect 4 clear to send 5 data set ready 6 ring indicator 7 receive line signal detect line status byte: bits 0 data ready 1 overrun error 2 parity error 3 framing error 4 break detect 5 transmit holding register empty 6 transmit shift register empty 7 time out note: if bit 7 set then other bits are invalid All routines have AH=function number and DX=RS232 card number (0 based). AL=character to send or received character on exit, unless otherwise noted. entry AH 00h Initialize And Access Serial Communications Port bit pattern: BBBPPSLL BBB = baud rate: 110,150,300,600,1200,2400,4800,9600 PP = parity: 01 = odd, 11 = even S = stop bits: 0 = 1, 1 = 2 LL = word length: 10 = 7-bits, 11 = 8-bits AL parms for initialization: bit pattern: 0 word length 1 word length 2 stop bits 3 parity 4 parity 5 baud rate 6 baud rate 7 baud rate word length 10 7 bits 11 8 bits stop bits 0 1 stop bit 1 2 stop bits parity 00 none 01 odd 11 even baud rate 000 110 baud 001 150 baud 010 300 baud 011 600 baud 100 1200 baud 101 2400 baud 110 4800 baud 111 9600 baud (4800 on PCjr) DX port number return AH line status AL modem status Function 01h Send Character in AL to Comm Port DX (0 or 1) entry AH 01h AL character DX port number (0 or 1) return AH RS232 status code bit 0 data ready 1 overrun error 2 parity error 3 framing error 4 break detected 5 transmission buffer register empty 6 transmission shift register empty 7 timeout AL modem status bit 0 delta clear-to-send 1 delta data-set-ready 2 trailing edge ring detected 3 change, receive line signal detected 4 clear-to-send 5 data-set-ready 6 ring received 7 receive line signal detected Function 02h Wait For A Character From Comm Port DX entry AH 02h return AL character received AH error code (see above)(00h for no error) Function 03h Fetch the Status of Comm Port DX (0 or 1) entry AH 03h return AH set bits (01h) indicate comm-line status bit 7 timeout bit 6 empty transmit shift register bit 5 empty transmit holding register bit 4 break detected ("long-space") bit 3 framing error bit 2 parity error bit 1 overrun error bit 0 data ready AL set bits indicate modem status bit 7 received line signal detect bit 6 ring indicator bit 5 data set ready bit 4 clear to send bit 3 delta receive line signal detect bit 2 trailing edge ring detector bit 1 delta data set ready bit 0 delta clear to send Function 04h Extended Initialize (PC Convertible) entry AH 04h AL break status 01h if break 00h if no break BH parity 00h no parity 01h odd parity 02h even parity 03h stick parity odd 04h stick parity even BL number of stop bits 00h one stop bit 01h 2 stop bits (1½ if 5 bit word length) CH word length 00h 5 bits 01h 6 bits 02h 7 bits 03h 8 bits CL baud rate 00h 110 01h 150 02h 300 03h 600 04h 1200 05h 2400 06h 4800 07h 9600 08h 19200 return AL modem status AH line control status Function 05h Extended Communication Port Control (PS/2) entry AH 05h AL 00h read modem control register return BL modem control reg (see AL=1) AL 01h write modem control register BL modem control register: (for AL=00 and AL=01) bits 0 data terminal ready 1 request to send 2 out1 3 out2 4 loop 5,6,7 reserved return AH status ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 15h Cassette I/O │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0054h) Renamed "System Services" on PS/2 line Function 00h Turn Cassette Motor On (PC, PCjr only) entry AH 00h return AH 86h no cassette present CF set on error AH error code 00h no errors 01h CRC error 02h bad tape signals no data transitions (PCjr) 03h no data found on tape not used (PCjr) 04h no data no leader (PCjr) 80h invalid command 86h no cassette present not valid in PCjr note NOP for systems where cassette not supported Function 01h Turn Cassette Motor Off (PC, PCjr only) entry AH 01h return AH 86h no cassette present CF set on error AH error code note NOP for systems where cassette not supported Function 02h Read Blocks From Cassette (PC, PCjr only) entry AH 02h CX count of bytes to read ES:BX pointer to data buffer return CF set on error AH error code DX count of bytes actually read ES:BX pointer past last byte written note 1) NOP for systems where cassette not supported 2) Cassette operations normally read 256 byte blocks Function 03h Write Data Blocks to Cassette (PC, PCjr only) entry AH 03h CX count of bytes to write ES:BX pointer to data buffer return CF set on error AH error code (see 02h) CX 0 ES:BX pointer to last byte written+1 note 1) NOP for systems where cassette not supported 2) The last block is padded to 256 bytes with zeroes if needed 3) No errors are returned by this service Function 0Fh ESDI Format Unit Periodic Interrupt (PS/2 50, 60, 80) entry AH 0Fh AL phase code 00h reserved 01h surface analysis 02h formatting return CF clear if formatting should continue set if it should terminate note Called during ESDI drive formatting after each cylinder is completed Function 10h TopView API Function Calls (TopView) entry AH 00h PAUSE Give Up CPU Time return 00h after other processes run 01h GETMEM allocate "system" memory BX number of bytes to allocate return ES:DI pointer to block of memory 02h PUTMEM deallocate "system" memory ES:DI pointer to previously allocated block return block freed 03h PRINTC display character/attribute on screen BH attribute BL character DX segment of object handle for window note BX=0 does not display anything, it only positions the hardware cursor 10h unknown AL 04h thru 12h return TopView - unimplemented in DV 2.0x pops up "Programming error" window in DV 2.0x 11h unknown 12h unknown 13h GETBIT define a 2nd-level interrupt handler ES:DI pointer to FAR service routine return BX bit mask indicating which bit was allocated 0 if no more bits available 14h FREEBIT undefine a 2nd-level interrupt handler BX bit mask from int 15/AH 13h 15h SETBIT schedule one or more 2nd-level interrupts BX bit mask for interrupts to post return indicated routines will be called at next ??? 16h ISOBJ verify object handle ES:DI possible object handle return BX -1 if ES:DI is a valid object handle 0 if ES:DI is not 17h TopView - unimplemented in DV 2.00 return pops up "Programming Error" window in DV 2.00 18h LOCATE Find Window at a Given Screen Location BH column BL row ES segment of object handle for ? (0 = use default) return ES segment of object handle for window which is visible at the indicated position 19h SOUND Make Tone BX frequency in Hertz CX duration in clock ticks (18.2 ticks/sec) return immediately, tone continues to completion note If another tone is already playing, the new tone does not start until completion of the previous one. In DV 2.00, it is possible to enqueue about 32 tones before the process is blocked until a note completes. In DV 2.00, the lowest tone allowed is 20 Hz 1Ah OSTACK Switch to Task's Internal Stack return stack switched 1Bh BEGINC Begin Critical Region return task-switching temporarily disabled note Will not task-switch until END CRITICAL REGION (AH=1Ch) is called 1Ch ENDC End Critical Region return task-switching enabled 1Dh STOP STOP TASK ES segment of object handle for task to be stopped (= handle of main window for that task) return indicated task will no longer get CPU time note At least in DV 2.00, this function is ignored unless the indicated task is the current task. 1Eh START Start Task ES segment of object handle for task to be started (== handle of main window for that task) return Indicated task is started up again 1Fh DISPEROR Pop-Up Error Window BX bit fields: 0-12 number of characters to display 13,14 which mouse button may be pressed to remove window 00 either 01 left 10 right 11 either 15 beep if 1 DS:DI pointer to text of message CH width of error window (0 = default) CL height of error window (0 = default) DX segment of object handle return BX status: 1 left button pressed 2 right button pressed 27 ESC key pressed note Window remains on-screen until ESC or indicated mouse button is pressed 20h TopView - unimplemented in DV 2.0x return pops up "Programming Error" window in DV 2.0x 21h PGMINT Interrupt Another Task BX segment of object handle for task to interrupt DX:CX address of FAR routine to jump to next time task is run return nothing? note The current ES, DS, SI, DI, and BP are passed to the FAR routine 22h GETVER Get Version BX 00h return BX nonzero, TopView or compatible loaded BH minor version BL major version notes TaskView returns BX = 0001h DESQview 2.0 returns BX = 0A01h 23h POSWIN Position Window BX segment of object handle for parent window within which to position the window (0 = full screen) CH # columns to offset from position in DL CL # rows to offset from position in DL DL bit flags 0,1 horizontal position 00 current 01 center 10 left 11 right 2,3 vertical position 00 current 01 center 10 top 11 bottom 4 don't redraw screen if set 5-7 not used ES segment of object handle for window to be positioned return nothing 24h GETBUF Get Virtual Screen Information BX segment of object handle for window (0=default) return CX size of virtual screen in bytes DL 0 or 1, unknown ES:DI address of virtual screen 25h USTACK Switch Back to User's Stack return stack switched back note Call only after int 15h,fn1Ah 26h-2Ah DesQview (TopView?) - unimplemented in DV 2.0x return pops up "Programming Error" window in DV 2.0x 2Bh POSTTASK Awaken Task DesQview 2.0 (TopView?) BX segment of object handle for task return nothing 2Ch Start New Application in New Process DesQview 2.0 (TopView?) ES:DI pointer to contents of .PIF/.DVP file BX size of .PIF/.DVP info return BX segment of object handle for new task 2Dh Keyboard Mouse Control DesQview 2.0 BL subfunction 00h determine whether using keyboard mouse 01h turn keyboard mouse on 02h turn keyboard mouse off return (calling BL was 00h) BL 0 using real mouse 1 using keyboard mouse Function 11h Topview commands entry AH 11h AL various note In DesQview 2.0x, these function calls are identical to AH=0DEh, so see those below Function 20h PRINT.COM (DOS internal) (AT, XT-286, PS/2 50+) entry AH 20h AL subfunction 00h unknown (PRINT) 01h unknown (PRINT) 10h sets up SysReq routine on AT, XT/286, PS/2 11h completion of SysReq routine (software only) note 1) AL=0 or 1 sets or resets some flags which affect what PRINT does when it tries to access the disk Function 21h Power-On Self Test (POST) Error Log (PS/2 50+) entry AH 21h AL 00h read POST log 01h write POST log BH device ID BL error code return CF set on error AH status 00h OK BX number of error codes stored ES:DI pointer to error log 01h list full 80h invalid command 86h unsupported note The log is a series of words, the first byte of which identifies the error code and the second the device. Function 40h Read/Modify Profiles (Convertible) entry AH 40h AL 00h read system profile in CX,BX 01h write system profile from CX, BX 02h read internal modem profile in BX 03h write internal modem profile from BX BX profile info return BX internal modem profile (from 02h) CX,BX system profile (from 00h) Function 41h Wait On External Event (Convertible) entry AH 41h AL condition type bits 0-2: condition to wait for 0 any external event 1 compare and return if equal 2 compare and return if not equal 3 test and return if not zero 4 test and return if zero bit 3: reserved bit 4: 1=port address, 0=user byte bits 5-7: reserved BH condition compare or mask value condition codes: 0 any external event 1 compare and return if equal 2 compare and return if not equal 3 test and return if not zero 4 test and return if zero BL timeout value times 55 milliseconds 0 if no time limit DX I/O port address (if AL bit 4 = 1) ES:DI pointer to user byte (if AL bit 4 = 0) Function 42h Request System Power Off (Convertible) entry AH 42h AL 00h to use system profile 01h to force suspend regardless of profile Function 43h Read System Status (Convertible) entry AH 43h return AL status bits: 0 LCD detached 1 reserved 2 RS232/parallel powered on 3 internal modem powered on 4 power activated by alarm 5 standby power lost 6 external power in use 7 battery low Function 44h (De)activate Internal Modem Power (Convertible) entry AH 44h AL 00h to power off 01h to power on Function 4Fh Keyboard Intercept (except PC, PCjr, and XT) entry AH 4Fh AL scan code, CF set return AL scan code, CF set if processing desired note Called by int 9 handler to translate scan codes Function 80h Device Open (AT, XT/286, PS/2) entry AH 80h BX device ID CX process ID return CF set on error AH status Function 81h Device Close (AT, XT/286, PS/2) entry AH 81h BX device ID CX process ID return CF set on error AH status Function 82h Program Termination (AT, XT/286, PS/2) AH 82h BX device ID return: CF set on error AH status note Closes all devices opened with function 80h Function 83h Event Wait (AT, XT/286, Convertible, PS/2) entry AH 83h AL 00h to set interval 10h to cancel CX,DX number of microseconds to wait (granularity is 976 microseconds) ES:BX pointer to memory flag (bit 7 is set when interval expires) (pointer is to caller's memory) return CF set (1) if function already busy Function 84h Read Joystick Input Settings (AT, XT/286, PS/2) entry AH 84h DX 00h to read the current switch settings (return in AL) 01h to read the resistive inputs return AX A(X) value BX A(Y) value CX B(X) value DX B(Y) value AL switch settings (bits 7-4) Function 85h System Request (SysReq) Key Pressed (except PC, PCjr, XT) entry AH 85h return AL 00h key pressed 01h key released note Called by keyboard decode routine Function 86h Elapsed Time Wait (except PC, PCjr, XT) AH 86h CX,DX number of microseconds to wait return CF clear after wait elapses CF set immediately due to error note Only accurate to 977 microseconds Function 87h Extended Memory Block Move (286/386 machines only) AH 87h CX number of words to move ES:SI pointer to Global Descriptor Table (GDT) offset 00h null descriptor 08h uninitialized, will be made into GDT descriptor 10h descriptor for source of move 18h descriptor for destination of move 20h uninitialized, used by BIOS 28h uninitialized, will be made into SS descriptor return CF set on error AH status 00h source copied into destination 01h parity error 02h interrupt error 03h address line 20 gating failed Function 88h Extended Memory Size Determine (AT, XT/286, PS/2) entry AH 88h return AX # of contiguous 1K blocks of memory starting at address 1024k Function 89h Switch Processor to Protected Mode (AT, XT/286, PS/2) entry AH 89h BH interrupt number of IRQ 8 (IRQ 9Fh use next 7 interrupts) BL interrupt number of IRQ 0 (IRQ 17h use next 7 interrupts) CX offset into protected mode CS to jump to DS:SI pointer to Global Descriptor Table for protected mode offset 00h null descriptor 08h GDT descriptor 10h IDT descriptor 18h DS 20h ES 28h SS 30h CS 38h uninitialized, used to build descriptor for BIOS CS return AH 0FFh error enabling address line 20 CF set on error Function 90h Device Busy Loop (except PC, PCjr, XT) entry AH 90h AL type code: 00h disk 01h diskette 02h keyboard 03h PS/2 pointing device 80h network (ES:BX = pointer to network control block) 0FCh hard disk reset (PS/2) 0FDh diskette motor start 0FEh printer ES:BX pointer to request block for type codes 80h through 0BFh return CF 1 (set) if wait time satisfied 0 (clear) if driver must perform wait note Used by NETBIOS Type codes are allocated as follows: 00h-7Fh non-reentrant devices; OS must arbitrate access 80h-BFh reentrant devices; ES:BX points to a unique control block C0h-FFh wait-only calls, no complementary int 15, fn91h call Function 91h Set Flag and Complete Interrupt (except PC, PCjr, XT) entry AH 91h AL type code (see AH=90h above) ES:BX pointer to request block for type codes 80h through 0BFh return AH 0 note Used by NETBIOS Function 0C0h Get System Configuration (XT after 1/10/86, PC Convertible, XT/286, AT, PS/2) entry AH 0C0h return CF 1 if BIOS doesn't support call ES:BX pointer to ROM system descriptor table dword number of bytes in the following table (norm. 16 bytes) byte system ID byte; see Chapter 2 for interpretation byte secondary ID distingushes between AT and XT/286, etc. byte BIOS revision level, 0 for 1st release, 1 for 2nd, etc. byte feature information 80h DMA channel 3 used by hard disk BIOS 40h 2nd 8259 installed 20h realtime clock installed 10h int 15h, fn 04h called upon int 09h 08h wait for external event supported (int 15fn41) used on Convertible; reserved on PS/2 systems 04h extended BIOS area allocated at 640k 03h reserved 02h bus is Micro Channel instead of PC 01h reserved 00h reserved byte unknown (set to 0) (reserved by IBM) byte unknown (set to 0) (reserved by IBM) byte unknown (set to 0) byte unknown (set to 0) (Award copyright here) note 1) Int 15h is also used for the Multitask Hook on PS/2 machines. No register settings availible yet. 2) The 1/10/86 XT BIOS returns an incorrect value for the feature byte. Function 0C1h System - Return Extended-BIOS Data-Area Segment Address (PS/2) entry AH 0C1h return CF set on error ES segment of data area Function 0C2h Pointing Device BIOS Interface (DesQview 2.x) (PS/2) entry AH 0C2h AL 00h enable/disable BH 00h disable 01h reset return BH device ID 02h set sampling rate BH 00h 10/second 01h 20/second 02h 40/second 03h 60/second 04h 80/second 05h 100/second 06h 200/second 03h set resolution BH 00h one count per mm 01h two counts per mm 02h four counts per mm 03h eight counts per mm 04h get type return BH device ID 05h initialize BH data package size (1 - 8 bytes) 06h get/set scaling factor BH 00h return device status return BL status byte bit 0: right button pressed bit 1: reserved bit 2: left button pressed bit 3: reserved bit 4: 0=1:1 scaling, 1=2:1 scaling bit 5: device enabled bit 6: 0=stream mode, 1=remote mode bit 7: reserved CL resolution (see function 03h) DL sample rate, reports per second 01h set scaling at 1:1 02h set scaling at 2:1 07h set device handler address ES:BX user device handler return AL 00h return CF set on error AH status 00h successful 01h invalid function 02h invalid input 03h interface error 04h need to resend 05h no device handler installed note The values in BH for those functions that take it as input are stored in different locations for each subfunction Function 0C3h Enable/Disable Watchdog Timeout (PS/2 50+) entry AH 0C3h AL 00h disable 01h enable BX timer counter return CF set on error note The watchdog timer generates an NMI Function 0C4h Programmable Option Select (PS/2 50+) entry AH 04Ch AL 00h return base POS register address 01h enable slot BL slot number 02h enable adapter return CF set on error DX base POS register address (if function 00h) Function 0DEh DesQview Services (DesQview) entry AH 0DEh AL 00h Get Program Name return AX offset into DESQVIEW.DVO of current program's record: byte length of name n bytes name 2 bytes keys to invoke program (second = 00h if only one key used) word ? (I see 0 always) byte end flag: 00h for all but last entry, which is 0FFh 01h Update "Open Window" Menu return none note Reads DESQVIEW.DVO, disables Open menu if file not in current directory 02h unimplemented in DV 2.0x return nothing (NOP in DV 2.0x) 03h unimplemented in DV 2.0x return nothing (NOP in DV 2.0x) 04h Get Available Common Memory return BX bytes of common memory available CX largest block available DX total common memory in bytes 05h Get Available Conventional Memory return BX K of memory available CX largest block available DX total conventional memory in K 06h Get Available Expanded Memory return BX K of expanded memory available CX largest block available DX total expanded memory in K 07h APPNUM Get Current Program's Number return AX number of program as it appears on the "Switch Windows" menu 08h GET (unknown) return AX 0 unknown 1 unknown 09h unimplemented in DV 2.00 return nothing (NOP in DV 2.00) 0Ah DBGPOKE Display Character on Status Line BL character return character displayed, next call will display in next position (which wraps back to the start of the line if off the right edge of screen) note 1) Displays character on bottom line of *physical* screen, regardless of current size of window (even entirely hidden) 2) Does not know about graphics display modes, just pokes the characters into display memory 0Bh APILEVEL Define Minimum API Level Required BL API level >2 pops up "You need a newer version" error window in DV 2.00 BH unknown return AX maximum API level? 0Ch GETMEM Allocate "System" Memory BX number of bytes return ES:DI pointer to allocated block 0Dh PUTMEM Deallocate "System" Memory ES:DI pointer to previously allocated block return nothing 0Eh Find Mailbox by Name (DV 2.0+) ES:DI pointer to name to find CX length of name return BX 0 not found 1 found DS:SI object handle 0Fh Enable DesQview Extensions (DV 2.0+) return AX and BX destroyed (seems to be bug, weren't saved & restored) note 1) Sends a manager stream with opcodes AEh, BDh, and BFh to task's window 2) Enables an additional mouse mode 10h PUSHKEY PUT KEY INTO KEYBOARD INPUT STREAM (DV 2.0+) BH scan code BL character return BX unknown (sometimes, but not always, same as BX passed in) note A later read will get the keystroke as if it had been typed by the user 11h ENABLE/DISABLE AUTO JUSTIFICATION OF WINDOW (DV 2.0+) BL 0 viewport will not move automatically nonzero viewport will move to keep cursor visible return none 12h unknown (DV 2.0+) BX 0 clear something? nonzero set something? return none ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 16h Keyboard I/O │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0058h) access the keyboard Function 00h Get Keyboard Input - read the next character in keyboard buffer, if no key ready, wait for one. entry AH 00h return AH scan code AL ASCII character Function 01h Check Keystroke Buffer - Do Not Clear entry AH 01h return ZF 0 (clear) if character in buffer 1 (set) if no character in buffer AH scan code of character (if ZF=0) AL ASCII character if applicable note Keystroke is not removed from buffer Function 02h Shift Status - fetch bit flags indicating shift status entry AH 02h return AL bit codes (same as [0040:0017]) bit 7 Insert state bit 6 CapsLock state bit 5 NumLock state bit 4 ScrollLock state bit 3 Alt key bit 2 Control key bit 1 Left shift (left caps-shift key) bit 0 Right shift (right caps-shift key) note other codes found at [0040:0018] bit 7 Insert shift (Ins key) bit 6 Caps shift (CapsLock key) bit 5 Num shift (NumLock key) bit 4 Scroll shift (ScrollLock key) bit 3 Hold state (Ctrl-NumLock is in effect) Function 03h Keyboard - Set Repeat Rate (PCjr, AT, XT/286, PS/2) entry AH 03h AL 00h reset typematic (PCjr) 01h increase initial delay (PCjr) 02h increase continuing delay (PCjr) 03h increase both delays (PCjr) 04h turn off typematic (PCjr) 05h set typematic rate (AT, PS/2) BH 00h-03h for delays of 250ms, 500ms, 750ms, or 1second 0,0 250ms 0,1 500ms 1,0 750ms 1,1 1 second BL 00h-1Fh for typematic rates of 30cps down to 2cps 00000 30 01011 10.9 10101 4.5 00001 26.7 01100 10 10110 4.3 00010 24 01101 9.2 10111 4 00011 21.8 01110 8.6 11000 3.7 00100 20 01111 8 11001 3.3 00101 18.5 10000 7.5 11010 3 00110 17.1 10001 6.7 11011 2.7 00111 16 10010 6 11100 2.5 01000 15 10011 5.5 11101 2.3 01001 13.3 10011 5.5 11110 2.1 01010 12 10100 5 11111 2 Function 04h Keyboard Click Toggle (PCjr and Convertible) entry AH 04h AL 00h for click off 01h for click on Function 05h Keyboard Buffer Write (AT or PS/2 with enhanced kbd) (XT/286, PS/2, AT with "Enhanced" keyboard) entry AH 05h CH scan code CL ASCII character return AL 01h if buffer full Function 10h Get Enhanced Keystroke And Read (F11, F12 Enhanced Keyb'd) (XT/286, PS/2, AT with "Enhanced" keyboard) entry AH 10h return AH scan code AL ASCII character if applicable Function 11h Check Enhanced Keystroke (F11-F12 on enhanced keyboard) (XT/286, PS/2, AT with "Enhanced" keyboard) entry AH 11h return ZF 0 (clear) if key pressed 1 if buffer empty AH scan code (when ZF=0) AL ASCII character if applicable (when ZF=0) note Keystroke is not removed from buffer Function 12h Extended Get Shift Status (F11, F12 Enhanced keyboard) entry AH 12h return AL bit 0 right Shift key depressed 1 left Shift key depressed 2 Control key depressed 3 Alt key depressed 4 ScrollLock state active 5 NumLock state active 6 CapsLock state active 7 insert state is active AH 0 left Control key pressed 1 left Alt key depressed 2 right Control key pressed 3 right Alt key depressed 4 Scroll Lock key depressed 5 NumLock key depressed 6 CapsLock key depressed 7 SysReq key depressed Function F0h Set CPU speed (Compaq 386) entry AH F0h set speed return unknown note used by Compaq DOS MODE command. parameters not availible ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 17h Printer │ └─────────────────────────────────────────────────────────────────────────────┘ (0:005Ch) access the parallel printer(s) AH is changed. All other registers left alone. Function 00h Print Character/send AL to printer DX (0, 1, or 2) entry AH 00h AL character DX printer to be used (0,1,2) return AH status byte bit 0 time out 1 unused 2 unused 3 I/O error 4 selected 5 out of paper 6 acknowledge 7 not busy Function 01h Initialize Printer - set init line low, send 0Ch to printer DX entry AH 01h DX printer port to be initialized (0,1,2) return status as below Function 02h Printer Status - read status of printer DX into AH entry AH 02h DX printer port to be used (0,1,2) return AH bit flags bit 7 0 = printer is busy bit 6 ACKnowledge line state bit 5 out-of-paper line state bit 4 printer selected line state bit 3 I/O error bit 2 unused bit 1 unused bit 0 time-out error ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 18h ROM BASIC │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0060h) Execute ROM BASIC at address 0F600h:0000h note 1) Often reboots a compatible ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 19h Bootstrap Loader │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0064h) Reads track 0, sector 1 into address 0000h:7C00h, then transfers control to that address. If no diskette drive available, transfers to ROM-BASIC or displays loader error message. Causes reboot of disk system if invoked while running. (no memory test performed). ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 1Ah Time of Day │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0068h) access the PC internal clock Function 00h Read System Time Counter entry AH 00h return CX high word of clock count DX low word of clock count AL 00h if clock was read or written (via AH=0,1) within the current 24-hour period. Otherwise, AL > 0 Function 01h Set Clock - set # of 55ms clock ticks in system time counter entry AH 01h CX:DX high word/low word count of timer ticks return none note 1) The clock ticks are incremented by timer interrupt at 18.2065 times per second or 54.9254milliseconds/count. Therefore: counts per second = 18 (12h) counts per minute = 1092 (444h) counts per hour = 65543 (10011h) counts per day = 1573040 (1800B0h) 2) counter is zeroed when system is rebooted Function 02h Read Real Time Clock Time (AT and after) entry AH 02h return CH hours in BCD CL minutes in BCD DH seconds in BCD DL 1 (set) if daylight savings time option CF 1 (set) if clock not operating Function 03h Set Real Time Clock Time (AT and after) entry AH 03h CH hours in BCD CL minutes in BCD DH seconds in BCD DL 0 (clear) if standard time 1 (set) if daylight savings time option return none Function 04h Read Real Time Clock Date (AT and after) entry AH 04h return CH century in BCD (19 or 20) CL year in BCD DH month in BCD DL day in BCD CF 1 (set) if clock not operating Function 05h Set Real Time Clock Date (AT and after) entry AH 05h CH century in BCD (19 or 20) CL year in BCD DH month in BCD DL day in BCD return none Function 06h Set Real Time Clock Alarm (AT and after) entry AH 06h CH hours in BCD CL minutes in BCD DH seconds in BCD return CF set if alarm already set or clock inoperable note Int 4Ah occurs at specified alarm time every 24hrs until reset Function 07h Reset Real Time Clock Alarm (AT and after) entry AH 07h return none Function 08h Set Real Time Clock Activated Power On Mode (Convertible) entry AH 08h CH hours in BCD CL minutes in BCD DH seconds in BCD Function 09h Read Real Time Clock Alarm Time and Status (Convertible and PS/2 Model 30) entry AH 09h return CH hours in BCD CL minutes in BCD DH seconds in BCD DL alarm status: 00h if alarm not enabled 01h if alarm enabled but will not power up system 02h if alarm will power up system Function 0Ah Read System-Timer Day Counter (XT-2 [640k motherboard], PS/2) entry AH 0Ah return CF set on error CX count of days since Jan 1,1980 Function 0Bh Set System-Timer Day Counter (XT-2 [640k motherboard], PS/2) entry AH 0Bh CX count of days since Jan 1,1980 return CF set on error Function 80h Set Up Sound Multiplexor (PCjr) (Tandy 1000?) entry AH 80h AL 00h source is 8253 channel 2 01h source is cassette input 02h source is I/O channel "audio in" 03h source is TI sound generator chip ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 1Bh Control-Break │ └─────────────────────────────────────────────────────────────────────────────┘ (0:006Ch) This interrupt is called when the keyboard scanner of the IBM machines detects Ctrl and Break pressed at the same time. note 1) If the break occurred while processing an interrupt, one or more end of interrupt commands must be send to the 8259 Programmable Interrupt Controller. 2) All I/O devices should be reset in case an operation was underway at the time. 3) It is normally pointed to an IRET during system initialization so that it does nothing, but some programs change it to return a ctrl-C scan code and thus invoke int 23h. ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 1Ch Timer Tick │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0070h) note 1) Taken 18.2065 times per second 2) Normally vectors to dummy IRET unless PRINT.COM has been installed. 3) If an application moves the interrupt pointer, it is the responsibility of that application to save and restore all registers that may be modified. ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 1Dh Vector of Video Initialization Parameters │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0074h) This doubleword address points to 3 sets of 16-bytes containing data to initialize for video modes for video modes 0 & 1 (40 column), 2 & 3 (80 column), and 4, 5 & 6 (graphics) on the Motorola 6845 CRT controller chip. 6845 registers: R0 horizontal total (horizontal sync in characters) R1 horizontal displayed (characters per line) R2 horizontal sync position (move display left or right) R3 sync width (vertical and horizontal pulse: 4-bits each) R4 vertical total (total character lines) R5 vertical adjust (adjust for 50 or 60 Hz refresh) R6 vertical displayed (lines of chars displayed) R7 vertical sync position (lines shifted up or down) R8 interlace (bits 4 and 5) and skew (bits 6 and 7) R9 max scan line addr (scan lines per character row) R10 cursor start (starting scan line of cursor) R11 cursor stop (ending scan line of cursor) R12 video memory start address high byte (6-bits) R13 video memory start address low byte (8-bits) R14 cursor address high byte (6-bits) R15 cursor address low byte (8-bits) 6845 Video Init Tables: table for modes 0 and 1 \ table for modes 2 and 3 \ each table is 16 bytes long and table for modes 4,5, and 6 / contains values for 6845 registers table for mode 7 / 4 words: size of video RAM for modes 0/1, 2/3, 4/5, and 6/7 8 bytes: number of columns in each mode 8 bytes: video controller mode byte for each mode note 1) There are 4 separate tables, and all 4 must be initialized if all video modes will be used. 2) The power-on initialization code of the computer points this vector to the ROM BIOS video routines. 3) IBM recommends that if this table needs to be modified, it should be copied into RAM and only the nescessary changes made. ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 1Eh Vector of Diskette Controller Parameters │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0078h) Dword address points to data base table that is used by BIOS. Default location is at 0F000:0EFC7h. 11-byte table format: bytes: 00h 4-bit step rate, 4-bit head unload time 01h 7-bit head load time, 1-bit DMA flag 02h 54.9254 ms counts - delay till motor off (37-38 typ) 03h sector size: 00h 128 bytes 01h 256 bytes 02h 512 bytes 03h 1024 bytes 04h last sector on track (8 or 9 typical) 05h gap between sectors on read/write (42 typical) 06h data length for DMA transfers (0FFh typical) 07h gap length between sectors for format (80 typical) 08h sector fill byte for format (0F6h typical) 09h head settle time (in milliseconds) (15 to 25 typical) DOS 1.0 0 DOS 2.10 15 DOS 3.1 1 10h motor start time (in 1/8 second intervals) (2 to 4 typ.) DOS 2.10 2 note 1) This vector is pointed to the ROM BIOS diskette tables on system initialization 2) IBM recommends that if this table needs to be modified, it should be copied into RAM and only the nescessary changes made. ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 1Fh Pointer to Graphics Character Extensions (Graphics Set 2) │ └─────────────────────────────────────────────────────────────────────────────┘ (0:007Ch) This is the pointer to data used by the ROM video routines to display characters above ASCII 127 while in CGA medium and high res graphics modes. note 1) Doubleword address points to 1K table composed of 28 8-byte character definition bit-patterns. First byte of each entry is top row, last byte is bottom row. 2) The first 128 character patterns are located in system ROM. 3) This vector is set to 000:0 at system initialization 4) Used by DOS' external GRAFTABL command ┌─────────────────────────────────────────────────────────────────────────────┐ │Interrupt 20h Terminate Current Program │ └─────────────────────────────────────────────────────────────────────────────┘ (0:0080h) Issue int 20h to exit from a program. This vector transfers to the logic in DOS to restore the terminate address, the Ctrl-Break address,and the critical error exit address to the values they had on entry to the program. All the file buffers are flushed and all handles are closed. You should close all files changed in length (see function calls 10h and 3Eh) before issuing this interrupt. If the changed file is not closed, its length, time, and date are not recorded correctly in the directory. For a program to pass a completion code or an error code when terminating, it must use either function call 4Ch (Terminate a Process) or 31h (Terminate Process and Stay Resident). These two methods are preferred over using int 20h and the codes returned by them can be interrogated in batch processing. Important: Before you issue an interrupt 20h, your program must ensure that the CS register contains the segment of its program segment prefix. Interrupt 20h DOS - Terminate Program entry no parameters return The following vectors are restored from the Program Segment Prefix: 0Ah Program Terminate 0Eh Control-C 12h Critical Error note IBM and Microsoft recommend using int 21 Fn 4Ch. Using int 20 is officially frowned upon since the introduction of DOS 2.0