Answers for "int 21h means"

int 21h means

INT 21H ;call the interrupt handler 0x21 which is the DOS Function dispatcher.

int 21h means

INT 21H ;Most calls to the DOS API are invoked using software interrupt 21h (INT 21h)
		;By calling INT 21h with a subfunction number in the AH processor 
        ;register and other parameters in other registers, various DOS services 
        ;can be invoked.

int 21h means

INT 21H ;Reads a character from the standard input device without copying it 
		;to the display. 
        ;If no character is ready it waits until one is available.