Biosmac

FILENAME: BIOSMAC.DOC
DESCRIPTION: This file documents the BIOS interface macros implemented in
the files IBIOS.MAC and MBIOS.MAC. Note that the only difference between the
two files is that IBIOS.MAC uses TASM's Ideal mode while MBIOS.MAC uses
TASM's MASM mode.
CallBIOS
--------
Function: Calls the specified BIOS interrupt/service.
Input
Interrupt - Interrupt number
Service - Service number
Output
none
Registers modified: ah, flags
Syntax: CallBIOS Interrupt, Service
LoadBH
------
Function: Loads BH with the a value. Presumably the video page. If no value
is provided BH is initialized to 0.
Input
Value - value to put in BH
Output
none
Registers modified: bh
Syntax: LoadBH Value
SetVideoMode
------------
Function: Sets the current video mode.
BIOS Interrupt: 10h Service: 00h
Input
Mode - new video mode as defined below
---- ----------------------------------------------------
0h 40x25 Black and White
1h 40X25 Color
3h 80x25 Color
4h 320x200 4-Color graphics
5h 320x200 4-Color graphics(color burst off)
7h Monochrome adapter Text display
8h 160x200 16-Color graphics(PCjr)
0Ah 640x200 4-Color graphics(PCjr)
0Dh 320x200 16-Color graphics(EGA)
0Eh 640x200 16-Color graphics(EGA)
0Fh 640x350 Monochrome graphics(EGA)
10h 640x350 4-Color or 16-Color graphics(EGA)(depends on
available RAM)
11h 640x480 2-Color graphics(VGA)
----------------------------------------------------
Output
none
Registers modified: ah, Flags
Syntax: SetVideoMode Mode

SetCursorShape
--------------
Function: Sets the cursors shape. The parameters passed to it indicate the
starting and ending scan lines to use when displaying the cursor.
On a monochrome system the default setting is lines 6-7. Setting
the scan lines to 0-7 would result in a block cursor. On a color
system the default setting is 14-15. Setting the starting scan line
to 15 and the ending scan line to 0 would result in a cursor with a
line on the top and bottom.
Input
Starting - starting scan line
Ending - ending scan line
Output
none
Registers modified: ah, cx, Flags
Syntax: SetCursorShape Starting, Ending
GotoXY
------
Function: Positions the cursor.The new cursor position is provided in the
parameters Row and Column. The caller can optionally provide the
video page to use. If Page isn't defined, page 0 is assumed.
Input
Row (y coordinate)
Column (x coordinate)
Page - Display page to check
Output
none
Register modified: ax, bh, dx, Flags
Syntax: GotoXY Row, Column, Page
WhereXY
-------
Function: Determines the current cursor position and the cursor's shape. The
Page parameter indicates the video page to check and is optional.
If the Page parameter is not specified, page 0 is assumed.
Input
Page - Display page to check
Output
ch - Starting line for cursor
cl - Ending line for cursor
dh - row (y coordinate)
dl - column (x coordinate)
Register modified: ax, cx, dx, Flags
Syntax: WhereXY Page
GetCursorShape
--------------
Function: Returns the shape of the cursor. Note that because the BIOS call to
get the cursor's position returns this information we simply call
the WhereXY macro.
Input
none
Output
ch - starting scan line of cursor
cl - ending scan line of cursor
Registers modified: ax, cx, dx, Flags
Syntax: GetCursorShape

GetLightPenPos
--------------
Function: Returns the position of the light pen.
Input
none
Output
ah = 0 - light pen not down/not triggered
1 - light pen down/triggered
ch - pixel vertical coordinate
bx - pixel horizontal coordinate
dh - character vertical coordinate
dl - character horizontal coordinate
Registers modified: ah, bx, ch, dx, Flags
Syntax: GetLightPenPos
SetDisplayPage
--------------
Function: Sets the current display page. Note that the Page parameter is
optional. If it is not provided, video page 0 is used.
Input
Page - Desired display page as defined below
PAGE MODE HARDWARE
---- ---- --------
0-7 00h and 01h CGA
0-3 02h and 03h CGA
0-7 02h and 03h EGA
0-7 0Dh EGA
0-3 0Eh EGA
0-1 0Fh EGA
0-1 10h EGA
Output
none
Registers modified: ah, Flags
Syntax: SetDisplayPage Page
ScrollUp
--------
Function: Scrolls the indicated part of the screen up LineCount times. Any
blank lines created are initialized to the color indicated in the
Attrib parameter. The coordinate parameters are optional. If they
are not provided, the routine scrolls the entire screen. The routine
assumes there are 80 columns on the screen. However, it checks how
many lines are currently available (25/43/50) if the coordinate
parameters aren't provided.
Input
LineCount - # of lines to scroll
Attrib - Attribute to use for new lines
x1 - Upper left column
y1 - Upper row
x2 - Lower right column
y2 - Bottom row
Output
none
Registers modified: ax, bh, cx, dx, Flags
Syntax: ScrollUp LineCount, Attrib, x1, y1, x2, y2
ScrollDown
----------
Function: Scrolls the indicated part of the screen down LineCount times. Any
blank lines created are initialized to the color indicated in the

Attrib parameter. The coordinate parameters are optional. If they
are not provided, the routine scrolls the entire screen. The routine
assumes there are 80 columns on the screen. However, it checks how
many lines are currently available(25/43/50) if the coordinate
parameters aren't provided.
Input
LineCount - # of lines to scroll
Attrib - Attribute to use for new lines
x1 - Upper left column
y1 - Upper row
x2 - Lower right column
y2 - Bottom row
Output
none
Registers modified: ax, bh, cx, dx, Flags
Syntax: ScrollDown LineCount, Attrib, x1, y1, x2, y2
GetCharAttr
-----------
Function: Reads the character and attribute at the current cursor position of
the indicated video page. See SetDisplayPage for a definition of
the different video pages available. Note that the Page parameter
is optional. If it is not provided, video page 0 is used.
Input
Page - the video page to check
Output
ah - attribute
al - character
Registers modified: ax
Syntax: GetCharAttr Page
PutCharAttr
-----------
Function: Displays a character and attribute 'Count' times starting at the
current cursor position of the indicated page. Note that the Page
parameter is optional. If it is not provided, video page 0 is used.
Input
Character - character to display
Attribute - attribute to display the character(s) in
Count - number of times to display the character
Page - Video page to display the characters on
Output
none
Registers modified: ax, bx, cx, Flags
Syntax: PutCharAttr Character, Attribute, Count, Page
PutChar
-------
Function: Displays a character Count times beginning at the current cursor
position on the indicated display page. Note that the Page and
Color parameters are optional. If you provide the Color parameter,
you must also provide the Page parameter. If the Page parameter is
not provided, video page 0 is used. If the Color is not provided,
the character attribute of the current cursor location of the
indicate video page is used.
BIOS Interrupt: 10h Service: 0Ah
Input
Count - number of times to display the character
Page - video page to display character(s) on
Output

none
Registers modified: ax, bx, cx, Flags
Syntax: PutChar Character, Count, Page, Color
SetColorPalette
---------------
Function: Sets the CGA color palette that is used while displaying graphics
in 320x200 graphics mode(4 & 5). For more information on video
modes, see SetVideoMode above.
BIOS Interrupt: 10h Service: 0Bh
Input
Entry - Color palette id being set
Color - New color for palette entry
Output
none
Registers modified: ah, bx, Flags
Syntax: SetColorPalette Entry, Color
PutPixel
--------
Function: Displays a pixel on the screen. Note that the macro may only be
called while in graphics mode.
BIOS Interrupt: 10h Service: 0Ch
Input
X - horizontal position
Y - vertical position
Color - color/display method for pixel
Output
none
Syntax: PutPixel X, Y, Color
GetPixel
--------
Function: Reads information about the indicated pixel.
BIOS Interrupt: 10h Service: 0Dh
Input
X - horizontal position
Y - vertical position
Output
al - pixel information
Syntax: GetPixel X, Y
PutTTY
------
Function: Displays text to the console using teletype mode. Note that the
Color parameter is optional. If the Color parameter isn't provided,
the character will be displayed using the attribute of the current
cursor position.
BIOS Interrupt: 10h Service: 0Eh
Input
Color - color to display text in.
Page - video page to display character(s) on
Output
none
Registers modified: ax, bx, Flags
Syntax: PutTTY Character, Page, Color
GetVideoMode
------------
Function: Determines the current video mode and display page.
BIOS Interrupt: 10h Service: 0Fh

Input
None
Output
ah - Number of columns on screen
al - display mode as defined below
---- ----------------------------------------------------
1h 40X25 Color
3h 80x25 Color
5h 320x200 4-Color graphics(color burst off)
7h Monochrome adapter Text display
0Ah 640x200 4-Color graphics(PCjr)
0Dh 320x200 16-Color graphics(EGA)
0Eh 640x200 16-Color graphics(EGA)
0Fh 640x350 Monochrome graphics(EGA)
10h 640x350 4-Color or 16-Color graphics(EGA)(depends on
available RAM)
----------------------------------------------------
bh - Active display page
Register modified: ax, bx, Flags
Syntax: GetVideoMode
SetPaletteRegs
--------------
Function: Sets the EGA palette colors. Note that the macro may only be called
when running on an EGA.
Input
SubService - Select service as defined below
SERVICE FUNCTION
------- -----------------------------------------------------
0 If setting palette register
1 If setting border color register
2 If setting all palette registers and border register
3 If toggling blink/intensity bit(EGA only)
-----------------------------------------------------------------
IndexIntensity - palette register or blink/intensity bit as
defined below.
SERVICE FUNCTION
------- -------------------------------------------------
SubService = 0 Palette register to set
SubService = 3 IndexIntensity = 0 - Enable intensity
IndexIntensity = 1 - Enable blinking
-----------------------------------------------------------------
Color - color to store in register
ListSeg:ListOfs - address of new palette list
Output
none
Registers modified: ax, bx, dx, es, Flags
Syntax: SetPaletteRegs SubService, IndexIntensity, Color, ListSeg, ListOfs
ScreenRows
----------
Function: Returns the number of rows available on the screen.
Input

none
Output
dl - # of rows on the screen(25/43/50)
Registers modified: ax, dl, Flags
Syntax: ScreenRows
PutString
---------
Function: Displays a string to the indicated video page at the indicated
position. Note that the Page and Attribute parameters are optional.
If Page is not supplied, the macro will use page 0 by default. If
Mode = 0 or 1, Attribute must be supplied. If Mode = 2 or 3,
Attribute should not be supplied. Note that if you provide the
Attribute parameter, you must provide the Page parameter also. This
macro may only be used on IBM-AT, PS/2 and compatible machines.
Input
Mode - mode to write string in as defined below
MODE FUNCTION
---- --------
0 Attribute in bl, string contains character codes only,
cursor position isn't updated after write.
1 Attribute in bl, string contains character codes only,
cursor position is updated after write.
2 String contains alternating character codes and
attribute bytes, cursor position isn't updated after
write.
3 String contains alternating character codes and
attribute bytes, cursor position is updated after write.
--------------------------------------------------------------------
X - Vertical position to begin display of the string
Y - Horizontal position to begin display of the string.
StringSeg - Segment address of the string
StringOfs - Offset address of string in StringSeg
Length - Length of the string to be displayed
Page - Video page to display string to
Attribute - Optional parameter that indicates the attribute to
display the string in. This parameter should only be
provided if Mode = 0 or 1.
Output
none
Registers modified: ax, bx, cx, dx, bp, es, Flags
Syntax: PutString Mode, X, Y, StringSeg, StringOfs, Length, Page, Attribute
GetChar
-------
Function: Returns the next character in the BIOS keyboard buffer.
Input
none
Output
ah - keyboard scan code
al - ASCII character
Registers modified: ax, Flags
Syntax: GetChar
GetKbdStatus
------------
Function: Returns the BIOS keyboard status.
Input
none
Output
If key wating to be input:

Zero flag - clear
ah - keyboard scan code
al - ASCII character
If no key waiting to be input:
Zero flag - set
Registers modified: ax, Flags
Syntax: GetKbdStatus
GetKbdFlags
-----------
Function: Returns the BIOS keyboard flags.
Input
none
Output
al - BIOS keyboard flags byte:
BIT FUNCTION
--- --------
7 Insert ON
6 Caps Lock ON
5 Num Lock ON
4 Scroll Lock ON
3 Alt key DOWN
2 Ctrl key DOWN
1 Left-Shift key DOWN
0 Right-Shift key DOWN
Registers modified: al, Flags
Syntax: GetKbdFlags

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