DOS function call

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DOS Function call

1. If you want to realize output, you can use BIOS Function call and DOS Function call .
2. stay DOS There are many functions in , Each function is distinguished by a unique function number , amount to id.
3. The function number can only be saved to AH in .

Instruction set

01H

1. function ： Enter a character and display it immediately .

2. The input data is saved in AL in .

   mov ah,01h
   int 21h
   

02H

1. function ： Output a character .

2. Before using, you need to put the output characters or characters 16 Base number ASCII Save code to DL in .

   mov dl,'A'
   mov ah,02h
   int 21h
   

07H

1. function ： There is no display after entering a character , Continue with the following procedure .

2. Same as 01H, The input data is saved in AL in .

   mov ah,07h
   int 21h