All HMC models 7315-CO2 must be updated to at least this BIOS level before you can upgrade the HMC to V6R1.0 or greater. In addition, IBM strongly recommends upgrading to the latest BIOS for your HMC model, regardless of the version of the HMC code in use.

Follow these steps to update the current BIOS revision level on your HMC.

Create a diskette

1. Place a formatted diskette into your Windows PC diskette drive.
2. Execute the binary 24KT55A.exe from a Windows PC.
3. Select to write the BIOS to the diskette and create a bootable diskette.

Update the BIOS

The BIOS update procedure contains several steps.

1. Find and record the machine type and model (MTM) number of your HMC as follows:
   • Check the label on the front of the HMC.
   • Run the lshmc -v | grep TM command.
   The MTM should be 7315-C02
2. Find and record the serial number of the HMC as follows:
   • Check the label on the front of the HMC.
   • Run command lshmc -v | grep SE
3. Place the bootable diskette you created in the HMC diskette drive, and then reboot the HMC.
   
   If the diskette does not boot to the BIOS menu, you may need to alter the HMC's startup device list OR press F12 if the Startup Device Menu is enabled, and then boot from the Removable device.
   
   The system should boot to a blue screen that has three options:
   1. Flash 73xx-C02 to 24KT55A BIOS. No user input, MTM, S/N.
   2. Flash 73xx-C02 to 24KT55A BIOS. User input required.
   3. Set 73xx-C02 CMOS values supporting 24KT55A BIOS.
    
4. If the machine type and model is set to 7315-C02, then select option 1. The BIOS will be flashed. Do not power off the HMC until the update is completed. The HMC will reboot once the flash completes. Do not remove the diskette.
   
   If the machine type is 8305, select option 2, and then answer the required prompts:
   - Would you like to update the Serial Number ?
   Update the serial number only if you have replaced the system board of the HMC.
   Answer N for most users.
   
   - Would you like to update the Machine Type/Model ?
   
   Answer Y
   
   For POWER4 HMCs, the model should be 7315C02
   For POWER5 HMCs, the model should be 7315C02
   
   The BIOS will be flashed. Do not power off the HMC until the update is completed. The HMC will reboot once the flash completes. Do not remove the diskette.
   If the machine type is not 7315-C02 or 8305, then you have the wrong BIOS version. Remove the diskette and reboot the HMC.
5. After the BIOS has updated:
   1. Select option 3, "Set 73xx-C02 CMOS values supporting 24KT55A BIOS"
   2. After the HMC reboots, remove the diskette.
   3. Select F1 to boot to the IBM setup utility
   4. Verify that Flash EEPROM Revision Level is 24KT55AUS

The BIOS update is complete.