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Text File  |  1993-03-26  |  13KB  |  163 lines

  1.                                                                                 
  2. PRINT SELECTION FOR APAR - II06091 92/07/14                                     
  3. APAR= II06091  SER=                            DD DOC                           
  4. INFORMATION REGARDING INTERRUPTS AND 2.0 OS/2 IN AT BUS SYSTEMS                 
  5. ( OS2INFOAPAR OS2 INFOAPAR INFO APAR R200 OS2OTHER )                            
  6. STAT= INTRAN       FESN5NFO000-000  CTID= II0000 ISEV= 4                        
  7. SB92/06/11  RC          CL          PD           SEV= 4                         
  8.                        PE=                       TYPE= I                        
  9. RCOMP= INFOPCLIB    PC LIB INFO ITE RREL= R001                                  
  10. FCOMP=                              PFREL= F     TREL= T                        
  11. ACTION=             SEC/INT=                     DUP/                           
  12. USPTF=              PDPTF=                       DUPS 0                         
  13. DW92/06/11  RT          SC          FT                                          
  14. RE          PT          UP          LP                                          
  15. PV          AP          EN          FL                                          
  16. LC92/06/22  RU92/06/11                                                          
  17.                              CUST INST LVL/SU=                                  
  18. FAILING MODULE=              FAILING LVL/SU=                                    
  19. SYSROUTE OF:          RET APAR=             PS=                                 
  20. COMP OPER ENV=                                                                  
  21.                                                                                 
  22.                                                                                 
  23. SYSRES=      SYSIN=      SYSOUT=      CPU=             RE-IPL=                  
  24. OPTYPE=                 SPECIAL ACTIVITY=          REGRESSION=                  
  25. PRE-SCREEN NO.=          RSCP= RS000                                            
  26. ERROR DESCRIPTION:                                                              
  27.                                                                                 
  28. Information regarding interrupts and OS/2 2.0 in AT BUS systems                 
  29. ---------------------------------------------------------------                 
  30. ...                                                                             
  31. Under OS/2 interrupts can not be shared. Results                                
  32. are unpredictable if interrupts are shared. Sharing                             
  33. interrupts is not a problem under DOS. It is possible                           
  34. for devices that are sharing interrupts to work perfectly                       
  35. under DOS and have problems under OS/2.                                         
  36. ...                                                                             
  37. On an ISA machine there are a total of 15 IRQ levels                            
  38. available.  The standard settings, in order of priority,                        
  39. is as follows:                                                                  
  40. ...                                                                             
  41. ...                                                                             
  42.      IRQ#   Device Associated                                                   
  43.      ----   -----------------                                                   
  44.                                                                                 
  45.       0     System Timer                                                        
  46.       1     Keyboard                                                            
  47.       2     Secondary Interrupt Controller  (see note)                          
  48.        8    Realtime Clock                                                      
  49.        9    --- (see note)                                                      
  50.       10    --- free                                                            
  51.       11    --- free                                                            
  52.       12    --- free - reserved for aux dev                                     
  53.       13    Math Coprocessor                                                    
  54.       14    Hard Disk                                                           
  55.       15    --- free                                                            
  56.      3      COM2 (Serial Communications Port #2)                                
  57.      4      COM1 (Serial Communications Port #1)                                
  58.      5      LPT2 (Parallel Printer Port #2 - add. 278)                          
  59.      6      Diskette                                                            
  60.      7      LPT1 (Parallel Printer Port #1 - add. 3BC and 378)                  
  61. ...                                                                             
  62. ...                                                                             
  63. (Note:  On the IBM-AT (ISA bus) the IRQ9 pin is identical                       
  64.  with the IRQ22 pin on the original IBM-PC.  If you have an                     
  65.  older, 8-bit adapter whose documentation states that it                        
  66.  uses IRQ2 then be aware that this will actually be seen as                     
  67.  IRQ9 when plugged into the 16-bit ISA bus.)                                    
  68. ...                                                                             
  69. ...                                                                             
  70. If multiple hardware adapters of any kind (not just                             
  71. communications) are using the same IRQ level then the                           
  72. effect on your computer will be unpredictable.  However, with                   
  73. single tasking systems like DOS, the two adapters which are                     
  74. sharing the interrupt may never cause any problems since they                   
  75. may never be in use at the same time.                                           
  76. ...                                                                             
  77. OS/2, however, presents a different set of problems.  If we                     
  78. have two, three or four adapters, the probability is now high                   
  79. that they are used at the same time.  If some of adapters had                   
  80. been set up using shared interrupts then the scene is set for                   
  81. mysterious things to occur in OS/2.                                             
  82. ...                                                                             
  83. OS/2 can, however, detect that an interrupt line is shared                      
  84. and will disallow the simultaneous use.  Assume that COM1 and                   
  85. COM3 were sharing IRQ4 (a fairly common real situation).  If                    
  86. we tried to use both COM ports at the same time OS/2 would                      
  87. refuse to allow the second one to start.  A well written OS/2                   
  88. communications program would see and report the error from                      
  89. OS/2 that the port could not be opened.  A DOS application,                     
  90. however, will likely be unprepared to respond to this strange                   
  91. situation and it may simply hang there waiting forever for                      
  92. the port that will never open.                                                  
  93. ...                                                                             
  94. The solution for all of this is to make sure that all of your                   
  95. hardware adapters have their own unique I/O addresses and IRQ                   
  96. assignments.  Unfortunately, on an ISA machine, OS/2 has no                     
  97. way to query the computer to find out what these settings                       
  98. are.  Therefore, after checking and setting the adapters                        
  99. according to the instruction manuals you must also tell OS/2                    
  100. what you've done by placing explicit information into the                       
  101. CONFIG.SYS file.                                                                
  102. ...                                                                             
  103. ...                                                                             
  104. To summarize:                                                                   
  105. -------------                                                                   
  106. ...                                                                             
  107.         *) Even though there is some flexibility for Printer &                  
  108.            Comm. port assignment try to stick to the standard                   
  109.            assignment as shown in IRQ table at the beginning                    
  110.            of document.                                                         
  111. ...                                                                             
  112.         *) Available interrupts, in order of priority, are:                     
  113.            IRQ10, IRQ11, IRQ12, IRQ15, IRQ3 (if not used                        
  114.            for COM2), and IRQ5 (if not used for LPT2).                          
  115. ...                                                                             
  116.         *) Addresses and interrupts can be assigned in OS2                      
  117.            to comm ports as described in info apar II06069.                     
  118.            Standard assigment is as follows:                                    
  119.                 COM1 - 3F8 - IRQ 4 (default)                                    
  120.                 COM2 - 2F8 - IRQ 3 (default)                                    
  121.                 COM3 - 3E8                                                      
  122.                 COM4 - 2E8                                                      
  123.            There is no OS/2 default setting for COM3 and                        
  124.            COM4. It must be specified by the device=com.sys                     
  125.            statement in config.sys.                                             
  126. ...                                                                             
  127.         *) Printer port addresses and IRQ levels are hardcoded                  
  128.            in OS/2 as follows:                                                  
  129.                 3BC and 378     ==> IRQ7 (LPT1)                                 
  130.                 278             ==> IRQ5 (LPT2)                                 
  131.            Unlike the the comm ports, where the addresses                       
  132.            and the interrupts can be modified by the                            
  133.            device=com.sys in config.sys, the printer port                       
  134.            addresses and IRQ shown above are fixed.                             
  135.            OS2 assigns LPT1 to the highest printer port address                 
  136.            being used. The printer address is specified in the                  
  137.            printer adapter board.                                               
  138.            With OS/2 you can not use both addresses 3BC and 378                 
  139.            as printer port addresses. Both LPTs would be sharing                
  140.            IRQ7.                                                                
  141.            Unlike DOS, OS/2 uses interrupts for printing.                       
  142.            The interrupt is triggered by a signal line from                     
  143.            the printer, ACK. If the IRQs are not configured                     
  144.            correctly, or the printer cable is missing the ACK                   
  145.            line the printer may work under DOS and                              
  146.            have problems under OS/2.                                            
  147. ...                                                                             
  148.            An example of address and interrupt assignment is                    
  149.            follows:                                                             
  150.                    COM1 - 3F8,IRQ4                                              
  151.                    COM2 - 2F8,IRQ3                                              
  152.                    COM3 - 3E8,IRQ5 (IRQ5 not being used by lpt2)                
  153.                    COM4 - 2E8,IRQ10                                             
  154. ...                                                                             
  155.                    LPT1 - 378,IRQ7                                              
  156. ...                                                                             
  157.         *) If interrupt devices are occasionally losing data,                   
  158.            try moving to a higher priority unused interrupt.                    
  159. LOCAL FIX:                                                                      
  160.                                                                                 
  161.                                                                                 
  162.                                                                                 
  163.