On Thu, 20 Aug 2009 08:26:45 -0500, McKown, John wrote: > >Thanks. I was under the impression that the microcode load in a >zAAP and a zIIP was different from the microcode load in a CP. I >guess that I was thinking that because there definately is a >difference (minor) in the microcode load in an IFL and a CP. That's >what stops z/OS from IPL'ing on an IFL (check stop as I recall >from "messing around"). Of course, the argument then becomes if >a difference in the microcode is a "hardware difference" or not. >And if a zAAP and a zIIP had the identical microcode to each >other or a CP, how would z/OS know which was which? That >was my attempted point, which was poorly stated.
If I understand correctly, there is no microcode on a z10 processor. There is millicode, which differs from microcode in this regard - it is implemented using a superset of z/Architecture instructions. The processor can run in a special mode in which it executes the millicode to emulate an instruction that was not implemented in hardware. Millicode can also be used to alter the behavior of an instruction, for example if it is determined that there is an error in the hardware implementation. Unfortunately, the IBM journals are no longer available free. There was an excellent article about millicode a while ago. I see now that individual articles can now be purchased for $1.99. You might want to read the IBM System z10 Enterprise Class Technical Introduction, available at http://www.redbooks.ibm.com/redpieces/abstracts/sg247515.html In there, it says, "The z10 EC implements 894 instructions, of which 668 are implemented entirely in hardware." That is, there is no millicode (or microcode) to implement those 668 instructions. The Charles Webb presentation two years ago on what was then called the z6 processor said the same thing. By the way, you might want to be careful with "messing around" with trying to IPL z/OS on IFL, zIIP or zAAP. You might find yourself in violation of the T's & C's of those specialty engines by doing that. -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
