Text Mode Cursor: Difference between revisions

==Disabling The Cursor With the BIOS==

Moving the cursor with the [[BIOS]] is done through Int 0x10 (The general interrupt for screen functions) with AH set to 0x02. These are the registers used:

* AH = 0x01

* CH = 0x3f ; bits 6-7 are unused , if bit 5 set the cursor is disable (this bit may be cleared in the interrupt caller , see "Disabling The Cursor Without the BIOS" for safer way to disable the cursor) , bits 0-4 controll the cursor shape (if bits 0-4 all set the cursor is unvisiable regradless what's bit 5's state.)

And then Interrupt 0x10 and then vuala , there is no *VISIBLE cursor on the screen

*Even on GUI modes the cursor remains active so don't think about it to much.

==Disabling The Cursor Without the BIOS==

===Source in C===

<source lang="c">

/* void disable_cursor()

* by Elad Ashkcenazi

*/

void update_cursor()

{

outb(0x3D4, 0x0A);

outb(0x3D5, 0x3f); bits 6-7 must be 0 , if bit 5 set the cursor is disable , bits 0-4 controll the cursor shape (if bits 0-4 all set the cursor is unvisiable regardless what's bit 5 state.)

// cursor shape port to vga INDEX register

}

</source>

===Source in assembly===

<source lang="asm">

made by Elad Ashkcenazi

;=============================================================================

disable_cursor: pushfq

push rax

push rdx

mov dx,0x3d4

mov al,0xa ; index 0xa is the LOW cursor shape register

out dx,al

inc dx

mov al,0x3f ; bits 6-7 must be 0 , if bit 5 set the cursor is disable , bits 0-4 controll the cursor shape (if bits 0-4 all set the cursor is unvisiable regardless what's bit 5 state.)

out dx,al

pop rdx

pop rax

popfq

ret

</source>

* http://www.osdever.net/FreeVGA/vga/vga.htm