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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         :  ECD18015     DATE             : 93-06-17
 MANDATORY         :  N
 AUTOMATIC SHIPMENT:  N            SERVICE CODE     : 33
 PARTS SOURCE      :  YASU         AVAILABILITY DATE: 93/06
                                                                                
 PURPOSE:                                                                       

 To prevent memory error problems which may occur when Bus
 Master Adapter is installed in the PS/55 Model 5551-T Stage 2
 and this field EC was revised from EC# C80656 FBM# 79F5494.
                                                                                
  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                                                     
  -80MB HDD attached SCSI Adapter/A                                             
  -Token Ring 16/4 Bus-Master 32 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- B/M0005551 S/N  RANGE               B/M54G1625 00.5 00.5 
   T09 B/M0005551      97XXXXK             B/M54G1625 00.5 00.5 
   T0A B/M0005551      97XXXXN-->97XXXXP   B/M54G1625 00.5 00.5 
   T0B B/M0005551      97XXXXS             B/M54G1625 00.5 00.5 
   T19 B/M0005551      97FXXXX             B/M54G1625 00.5 00.5 
   T1A B/M0005551      97HXXXX             B/M54G1625 00.5 00.5 
   T1B                 97LXXXX                                  
                  (X IS ANY CHARACTER)                          

                                                                                
 PHYSICAL CHECK:                                                                

 Check the System Board P/N and EC#.                                            
 When the Bus Master Adapter is installed in the 55551-T Stage 2,               
 if the System Board is P/N 23F3346 and EC# C12856x or C80659x,                 
 install this FBM.                                                              
 (x means any Alpha/Numeric character)                                          
                                                                                
 PREREQUISITES: NONE                                                            
                                                                                
 COMPANION: NONE                                                                
                                                                                
 CONCURRENT: NONE                                                               
                                                                                
 DETAIL:                                                                        

 Replace the System Board with new P/N 54G1612.                                 
                                                                                
 NOTES:                                                                         

 Return the removed System Board with EC completion report                      
 to stock center as soon as possible after EC installation.                     
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