Mainframe Microcode

What is Microcode ?

Microcode is a layer of hardware-level instructions and/or data structures involved in the implementation of higher level machine code instructions in many computers and other processors; it resides in a special high-speed memory and translates machine instructions into sequences of detailed circuit-level operations. It helps separate the machine instructions from the underlying electronics so that instructions can be designed and altered more freely. [Taken from http://en.wikipedia.org/wiki/Microcode ] .

Some vendor use the term firmware or machine code. The latest machine use microcode instead of hard-wired CPU. Old machine like IBM3420 , storage using tape reel
have a hard-wired CPU . There have many wires that fill in the circuit board. The electronic components was huge. The capacitor was big.
I'm still remember when I dismantled the 3420 in one of the bank here. They start use it since 1980's and stop on last year. For servicing and operating 3420, I'm not familiar and normally we gave it to senior CE to handle.

Back to microde (MCL ) for mainframe . It is call LIC (licensed Internal Code ) . Its control all hardware components. Purpose of LIC as below :-

• Provides functionality
• Fixed (patch) for a component
• Allow us to change hardware functionality

LIC is installed in Hardware Management Console (HMC) and Support Element (SE) fixed disks.
HMC - LIC to control HMC application
SE - LIC to control SE application and CPC Code.

How to determine the HMC Code level ?

1. Log on as service ID
2. From the console action > View Console Information .

How to determinte the SE Code level ?

1. Select defined CPC (in HMC)
2. Select Views > Task List > Change Management .
3. Double click View System Information Task. (make sure Defined CPC is selected)
   
4. From the window pop out , you can see various microcode with EC number, Retrieved , Activate,Accepted level + description of EC .

Today, I'm doing Code Activation of Drv79 for machine z10 BC.
The code already downloaded via modem to the HMC. There are few ways to download the code.
First is thru modem connected to analog phone line. Second using predownloaded MCL into the SUL-DVD. All the code are download thru RETAIN support system . Therefore if the machine is not listed under Maintenance with IBM, code cannot be download and no latest patch will be install for the machine.


Few steps need to follow before Code Activation

1. Backup
2. Retrieved latest code
   
3. Accept current code
4. Activate code
   
5. Perform mirroring

After code activation completed , from the SE , under Change Management select Analyze Internal Code to view that all the MCL are successfully applied.

Duration of MCL activation depend the how many pending code need to activate . Please be reminded that MCL for HMC never disruptive to CPC but SE MCL may be disruptive to CPC.
Consult to your System Z IBM CE for the code activities first.

On next post- What is IBF (Internal Battery Feature) ?


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