I/O

Speaker
The piezoelectric system speaker is mounted on the system board. To enable it, install a jumper plug on pins 1 and 2 of the SPKR connector on the system board.
Otherwise, the SPKR connector can be used to replace the piezoelectric system speaker with a standard external speaker connected by a 2-wire, twisted-pair cable. The cable connector and speaker connector are keyed to ensure correct connection.

I/O Map

Address          Device                                
                                                       

0000 - 000F      DMA controller #1                     
                                                       

0020 - 0023      Interrupt controller #1               
                                                       

0024             SHASTA data register                  
                                                       

0025 - 0027      Interrupt controller #1               
                                                       

0028             SHASTA index register                 
                                                       

0029 - 003F      Interrupt controller #1               
                                                       

0040 - 0043      System timers                         
                                                       

0044 - 005F      Reserved                              
                                                       

0060 - 006F      Keyboard controller                   
                                                       

0070 - 0071      Real-time clock and NMI enable        
                                                       

0080 - 008F      DMA page registers                    
                                                       

00A0 - 00BF      Interrupt controller #2               
                                                       

00C0 - 00DF      DMA controller #2                     
                                                       

00F0             Coprocessor busy clear                
                                                       

00F1             Coprocessor busy reset                
                                                       

00F2 - 00FF      Available                             
                                                       

278 - 27F        LPT2                                  
                                                       

2E8 - 2EF        COM4                                  
                                                       

2F8 - 2FF        COM2                                  
                                                       

378 - 37F        LPT1                                  
                                                       

3E8 - 3EF        COM3                                  
                                                       

3F8 - 3FF        COM1