INT 10

INT 10h, INT 10H or INT 16 is shorthand for BIOS interrupt call 10_hex, the 17th interrupt vector in an x86-based computer system. The BIOS typically sets up a real mode interrupt handler at this vector that provides video services. Such services include setting the video mode, character and string output, and graphics primitives (reading and writing pixels in graphics mode).

To use this call, load AH with the number of the desired subfunction, load other required parameters in other registers, and make the call. INT 10h is fairly slow, so many programs bypass this BIOS routine and access the display hardware directly. Setting the video mode, which is done infrequently, can be accomplished by using the BIOS, while drawing graphics on the screen in a game needs to be done quickly, so direct access to video RAM is more appropriate than making a BIOS call for every pixel.

Normally a character cell has 8 scan lines, 0-7. So, CX=0607h is a normal underline cursor, CX=0007h is a full-block cursor. If bit 5 of CH is set, that often means "Hide cursor". So CX=2607h is an invisible cursor.

Some video cards have 16 scan lines, 00h-0Fh.

Some video cards don't use bit 5 of CH. With these, make Start>End (e.g. CX=0706h)

BH = Background Color and Foreground color. BH = 43h, means that background color is red and foreground color is cyan. Refer the BIOS color attributes

CH = Upper row number, CL = Left column number, DH = Lower row number, DL = Right column number

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