Device
and operation
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4.3.22 Specific features of console redirect module operation
BIOS has a console redirect module, designed to work with the board in the terminal mode. To
continue the module's operation after OS startup you must enable BIOS Setup option
“Redirection
After BIOS → Always”.
If there is no installed video adapter card, the video buffer is generated by the redirection module
and does not use the segment 0xB800. Therefore, the output of software that directly writes to the
video memory or uses unsupported Int 0x10 functions is either distorted or does not reach the
terminal at all. This peculiarity must be taken into account when writing applications that work in
configurations without a video adapter.
List of Int 0x10 functions supported by the redirect module:
• Int 0x10 , AH=0x00 - Set Video Mode
• Int 0x10 , AH=0x01 - Set Cursor Type
• Int 0x10 , AH=0x02 - Set Cursor Position
• Int 0x10 , AH=0x03 - Read Cursor Position
• Int 0x10 , AH=0x06 AL=0 - Clean a block.
• Int 0x10 , AH=0x08 - Read Character And Attribute At Cursor.
• Int 0x10 , AH=0x09 - Write Character And Attribute At Cursor.
• Int 0x10 , AH=0x0A - Write Character At Current Cursor.
• Int 0x10 , AH=0x0E - Write Text In Teletype Mode.
• Int 0x10 , AH=0x0F - Get Current Video State.
• Int 0x10 , AH=0x13 - Write String.
A list of Int 0x10 functions that are
NOT supported
by the redirect module:
• Int 0x10, AH=0x04 - Read Light Pen.
• Int 0x10, AH=0x05 - Select Active Display
• Int 0x10, AH=0x06 - Scroll Active Page Up.
• Int 0x10, AH=0x07 - Scroll Active Page Down.
• Int 0x10, AH=0x0B - Set Color Palette.
• Int 0x10, AH=0x0C - Write Graphics Pixel At Coordinate.
• Int 0x10, AH=0x0D - Read Graphics Pixel At Coordinate.
• Int 0x10, AH=0x10 - Set/Get Palette Registers.
• Int 0x10, AH=0x11 - Character Generator Routine.
• Int 0x10, AH=0x12 - Video Subsystem Configuration.