          September 12, 1991


          URGENT

          Dear System Administrator:

          We are informing you of a situation which occurred recently
          affecting a limited number of our workstations which are based
          upon the Motorola 25 MHz XC68040 microprocessor circuit
          manufactured with the 4D50D mask set.  Motorola's normal
          manufacturing procedures may include making changes to a circuit
          once it is in production, for reasons such as increasing
          fabrication yield.  However, a recent XC68040 circuit revision
          exhibits some unexpected behavior when operated in selected
          products.

          In order to correct this situation, we have mobilized our Customer
          Engineering organization to seek out the affected HP workstations.
          We also believe it would be mutually beneficial for you to help us
          identify and isolate HP systems containing 4D50D-mask XC68040
          microprocessors.  A special test utility is available to help you
          locate units needing a replacement XC68040 microprocessor.  All
          repairs related to this situation are free of charge.

          HP has determined that affected systems may have been shipped to
          your site.  If a HP Customer Engineer or other HP personnel has
          not yet contacted you, please call your local HP service office.
          The HP Customer Engineer will need your help in physically
          locating affected systems as quickly as possible, particularly
          those systems or upgrades that have not yet been installed.

          There are five affected HP workstations:
               * HP 9000 Model 380
               * HP Apollo Series 5500
               * HP Apollo 9000 Model 425e
               * HP Apollo 9000 Model 425t
               * HP Apollo 9000 Model 425s.
          These systems are potentially affected whether they were ordered
          directly or derived via upgrade from other models.  To put further
          bounds on the situation, we estimate that approximately 20% of the
          affected products shipped out of HP Manufacturing sites between
          July 1 and August 23 this year contain the 4D50D-mask XC68040
          microprocessor chip.  The XC68040-based products shipped by HP
          outside of that date range are unaffected, as they do not contain
          a 4D50D-mask microprocessor.

          Although this revision was extensively tested at Motorola, HP, and
          other users, the design defect was found only after HP had begun
          customer workstation shipments based on XC68040 microprocessors
          manufactured with the 4D50D mask set.  On this mask revision of
          the circuit, erroneous results which are invisible to the user may
          occur within a certain sequence of floating point instructions
          generated by HP-UX and Domain compilers.  Because of the rather
          unique and uncommon nature of this calculation error, the behavior
          was not observed during the testing process.  Motorola notified HP
          of the unexpected behavior, and is now producing a new revision of
          the microprocessor circuit (mask 9D50D) which solves the known
          problem.

          As mentioned earlier, there is a method whereby you can obtain a
          test code sequence to determine if your systems are affected.
          First, if you have a HP Support Services contract, you can obtain
          this special test code electronically through the HP Supportline
          electronic bulletin.  Use the following "patch number" identifier
          in HPSL to locate this special test code: for Domain, PD91_M0318,
          and for HP-UX, PHSS_0459.  Please call your HP Response Center if
          you have any problems obtaining this code through HPSL.  When
          calling the HP Response Center, refer to the password "4D50D MASK"
          to obtain the quickest response.  If you are not on HP Support
          Service, you should contact your local HP service office.  If you
          determine that you do indeed have affected system(s) before a HP
          Customer Engineer calls: in the U.S. please call 1 (800) 227-6556
          and identify the password "4D50D MASK", outside the U.S. please
          make a service call through your normal channels.  The defective
          part(s) will be replaced at your site as soon as possible.

          Please be assured, that we are doing everything necessary to
          correct all defective units and apologize in advance for any
          inconvenience this situation may cause you.

          Best Regards,

          Hewlett-Packard Company
          Customer Support Organization

          CH/lo
