While scanning the IBM web pages, I came across this URL

http://www.rs6000.ibm.com/support/micro/download.html

that talked about downloading RS/6000 microcode.  You had
to read a license agreement to obtain an unzip password,
which was **RS/6000** (11 characters).

  This was the place to download microcode for all RS/6000's.

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The command to see your current microcode level, is machine-
dependent.  For dweb1, which is a 7020-6C3, it's

  lscfg -vp | grep -p Platform

e.g. on dweb1 on 9-21-05, showed it to be at

      Platform Firmware:
        ROM Level.(alterable).......3F041021       
        Version.....................RS6K
        System Info Specific.(YL)...U0.1-P1-X1/Y1
      Physical Location: U0.1-P1-X1/Y1

and IBM's web site said the current level is 3F050715.


For my B50, the command is
  lscfg -vp | grep -p openprom

which shows

  Name:  openprom
    Model:  IBM,TCP99256
    Node:  openprom
    Physical Location: P1

That TCP99256 is my level from September, 1999 and the latest is 
TCP04195 from August, 2004.