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                           IBM ECA
              Engineering Change Announcement

Parts removed from this machine and returned to IBM must be genuine,
                      unaltered IBM Parts

         IBM World Trade Corporation, CE Department Germany
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 EC NUMBER         :  ECC80655     DATE             : 92-06-25
 MANDATORY         :  N
 AUTOMATIC SHIPMENT:  N            SERVICE CODE     : 33
 PARTS SOURCE      :  YASU         AVAILABILITY DATE: 92/05
                                                                                
 PURPOSE:                                                                       
 To prevent memory error problems which may occur when Bus
 Master Adapter is installed in the PS/55 Model 5551-S Stage 2.
 (Stage 2 machine has a white power switch lever)
                                                                                
 The following adapters have Bus Master Function.                               
 -Micro Channel SCSI Adapter/A (16Bit,32Bit)                                    
 -Inteligent Communication Adapter/A Portmaster                                 
 -Numeric Processing Adapter                                                    
 -Japanese Voice Adapter/A                                                      
                                                                                

 Type             Machines Affected                             
 Mod.  With       and/or Feature/Device    B/M to be  Serv Syst 
 Stg.  B/M        Description              Installed  Hour Hour 

 Plant 98                                                       

 5551-            S/N RANGE                                     
   S09 B/M0005551    970000A --> 974177B   B/M79F5493 00.5 00.5 
   S0A B/M0005551    970000F --> 975162F   B/M79F5493 00.5 00.5 
   S19 B/M0005551    97AA001 --> 97AL510   B/M79F5493 00.5 00.5 
   S1A B/M0005551    97CA001 --> 97CC180   B/M79F5493 00.5 00.5 

                                                                                
 PHYSICAL CHECK:                                                                
 If Bus Master Adapter is installed in the 5551-S Stage 2, only                 
 when all of the following conditions are satisfied,  you must                  
 install this FBM.                                                              
                                                                                
  1)EC number of the System Board P/N 38F6769 ---> EC# C12859x                  
                                             (x is any alphabet)                
  2)System Board Memory Size ---> 8MB MAX                                       
                             (exclude 2-8MB Expansion Memory)                   
                                                                                
 PREREQUISITES: NONE                                                            
                                                                                
 COMPANION: NONE                                                                
                                                                                
 CONCURRENT: NONE                                                               
                                                                                
 DETAIL:                                                                        
 Replace the System Board in the system unit.                                   
                                                                                
 NOTES:                                                                         
 Return the removed part with EC completion report to stock                     
 center as soon as possible after installing this FBM.                          
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