/ MS-DOS / MS-DOS. / 8 /

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( 8-5). . 8-1 .


                                                          8-1
                         
         
                  
         
                1            (RLS)
                2             (RDA)
                3             (THRE)
                4           (MS)
         

                ASCII
                     
                            1 2 3 4  
                                                    
                                                              
                                                                      
                                                                      
                                                 
                                                    
                                             
                                                
                                                       
                                                     
                                                      
                                                     
                             8259A        

                  .8-5.

" " (RLS), . RLS , :


- ( 0) .


- , ( ).


- .


- ( ).


" " (RDA), . .


" " (THRE). , , , , ( , ), . . , , , , .


" " (MS). , :


- () " " (CTS).


- " " (DSR).


- , " " (RI) 1.


- ( , , ), " " (RLSD) 1.


.


. - IBM ( IBM) OUT2 1 , . , . , , . 8259A.


MS-DOS ( 8086) , , . Intel 8259A. 8259A "" . 8259A, , () . 8259A , .


8259A ? , 8259A . , 8259A. , (IRQ) 8259A. , IRQ, . , IRQ , , . IBM PC IRQ. , , ( ), . 8259A IRQ, , , IRQ. , IRQ0, IRQ1 .


, MS-DOS 3.3 , COM1 COM4, , /. /, MS-DOS .


IBM PC , COM1 COM2, IRQ . , COM3 COM4 / IRQ . IRQ, COM3 COM4 , COM1 COM2. , COM1 COM2.


COM1 COM2 IRQ4 IRQ3, 12 11 (). , , DOS ( 21h) 35h 25h .


, /. 8086 , . , 8259A , , . , , ( , ), . , , STI ( ) . , , .


8259A , ? 8259A " " (EIO) . , EIO IRQ, , , 8259A , "" EOI ( 20h). "" , , . , . IRQ.


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