Download AMD Geode SC1201 Specifications

32087C
13.1.2
Video BIOS Support
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:
Parameter
Description
AH
01h
AL
Mode number
DS
Seg0
CL
Cursor end scan line
CH
Cursor start scan line
Returns:
Parameter
AX
13.1.3
Description
Last value programmed into CRTC
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:
Parameter
Description
AH
02h
BH
Page number (0 for graphics modes)
DS
Seg0
DL
Column
DH
Row
Returns:
None.
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AMD Geode™ GeodeROM Functional Specification