Editing IBM mainframe (section)

===Processor units===
The different processors on current IBM mainframes are:
* CP, [[central processor]]: general-purpose processor
* IFL, [[Integrated Facility for Linux]]: dedicated to [[Linux]] OSes (optionally under [[z/VM]])
* ICF, Integrated [[Coupling Facility]]: designed to support [[IBM Parallel Sysplex|Parallel Sysplex]] operations
* SAP, System Assist Processor: designed to handle various system accounting, management, and [[I/O channel]] operations
* [[zAAP]], System z Application Assist Processor: currently limited to run only [[Java (programming language)|Java]] and [[XML]] processing
* [[zIIP]], System z Integrated Information Processor: dedicated to run specific workloads including [[IBM Db2]], [[XML]], and [[IPSec]]

These are essentially identical, but distinguished for software cost control: all but CP are slightly restricted{{efn|All supported IBM operating systems test the type of processor they are running on and restrict usage in accordance with license terms.}} such they cannot be used to run arbitrary operating systems, and thus do not count in software licensing costs (which are typically based on the number of CPs).<ref>{{cite web|url=http://publib.boulder.ibm.com/infocenter/zos/basics/topic/com.ibm.zos.zmainframe/zmainframe_book.pdf|title=Mainframe concepts (page 31)|author=IBM corp.|year=2005|access-date=May 5, 2012|archive-date=July 8, 2012|archive-url=https://web.archive.org/web/20120708195859/http://publib.boulder.ibm.com/infocenter/zos/basics/topic/com.ibm.zos.zmainframe/zmainframe_book.pdf|url-status=live}}</ref>
There are other supporting processors typically installed inside mainframes such as [[cryptographic]] accelerators ([[CryptoExpress]]), the [[OSA-Express]] networking processor, and [[FICON]] Express disk I/O processors.

Software to allow users to run "traditional" workloads on zIIPs and zAAPs was briefly marketed by Neon Enterprise Software as "zPrime" but was withdrawn from the market in 2011 after a lawsuit by IBM.<ref>{{cite web|last=Radding|first=Alan|title=Bye bye zPrime on System z|date=June 6, 2011|url=http://dancingdinosaur.wordpress.com/2011/06/06/bye-bye-zprime-on-system-z/|publisher=DancingDinosaur|access-date=May 5, 2012|archive-date=June 30, 2012|archive-url=https://web.archive.org/web/20120630214501/http://dancingdinosaur.wordpress.com/2011/06/06/bye-bye-zprime-on-system-z/|url-status=live}}</ref>