to these 5 pools of characterized processors, there are three other categories of processor: Service Assist Processors (for assisting with I/O operations) which all machines have. Spare processors (to replace characterized processors in the event of a failure) which all machines have. Unpurchased processors (which can be purchased and then characterized) which all but the most fully characterized machines have. Models Enterprise Class The System z9 Enterprise Class server, formerly known as the System z9 109, was the flagship of the System z9 series until the announcement of the IBM System z10. The most powerful model, the 2094-S54, achieves approximately twice the transactional performance of its most powerful predecessor, the zSeries z990 (2084-332). A single 2094-S54 machine provides up to 54 main processors (plus scores of secondary processors), at least two spare main processors, and up to 512 GB of main memory. Minimum memory is 16 GB. The System z9 EC is available in five hardware model configurations: 2094-S08 2094-S18 2094-S28 2094-S38 2094-S54 Business Class On April 27, 2006, IBM announced the System z9 Business Class, also known as the z9 BC, as the successor to the zSeries z890 mainframe. IBM is positioning the z9 BC as a midrange system with a low cost of acquisition with up to twice the performance of the z890. The first z9 BCs began shipping on May 26, 2006. The z9 BC supports up to seven main processors (plus a dozen or more secondary processors). While the z9 BC can provide general purpose central processors (CPs), IBM is actively marketing the use of low cost specialty processors such as IFLs, zAAPs, and the new . (Every z9 BC can support at least three specialty engines even when maximally configured with CPs.) The z9 BC comes with a minimum of 8 GB of RAM and is expandable up to 64 GB. IBM offers kits that allow current z800 and z890 customers to upgrade to the z9 BC. A z9 BC customer can then upgrade to the z9 EC if extra capacity is required. The System z9 BC is available in two hardware model configurations: 2096-R07 2096-S07 The seven System z9 hardware configurations support scores of software model configurations: 2094-401 through 2094-754 for the EC and 2096-A01 through 2096-Z04 for the BC (plus IFL-only models). Pricing The acquisition price for the System z9 ranges from "about $100,000" (IBM reported U.S. 2006 price, 2096-A01 model) to millions