Specifications

166 AMD Geode™ GeodeROM Functional Specification
Video BIOS Support
32087C
13.1.2 Function 01h - Set Cursor Type
Description:
Changes the shape of the text mode cursor to a new start and end scan line shape. By setting the cursor start scan line
greater than the cell height on the screen, the text cursor is disabled (hidden). The standard method of disabling the
cursor is to pass a 20h as the start scan line value. This function has no effect in graphics mode.
In order to maintain compatibility with the CGA and EGA, the BIOS emulates an 8x8 cursor cell. In other words, when
the cell height is 16 scan lines (standard mode 3), calling this with a start of 06h and an end of 07h actually sets the
start and end to 0Dh and 0Eh. This emulation functionality can be disabled by calling Alternate Select Function (12h),
Subfunction 34h.
When emulated, the cursor follows these general rules:
• Bit 5 = 1: No cursor
• Start scan < end scan<= 3: Overbar cursor
• Start scan + 2 >= end scan: Underline cursor
• Start >= 2: Half block cursor
• Start <= 2: Full block cursor
• End < Start: Full block cursor
Passed:
Returns:
13.1.3 Function 02h - Set Cursor Position
Description:
Moves the current cursor position. All character read/write functions depend on the cursor position to determine where
to read or write the next character. In graphics mode, this text position is still maintained even though there is no actual
blinking cursor. In modes that can have more than one video page, the cursor position can be changed even when the
current screen page is different from that passed into this function.
Passed:
Returns:
None.
Parameter Description
AH 01h
AL Mode number
DS Seg0
CL Cursor end scan line
CH Cursor start scan line
Parameter Description
AX Last value programmed into CRTC
Parameter Description
AH 02h
BH Page number (0 for graphics modes)
DS Seg0
DL Column
DH Row