ZSeries

IBM e(logo)server zSeries is the name for the System 390 (S/390) family since December 2001,the then current models being rebranded as the zSeries 900 family. They are the successors to the System/370s and more specifically the System 370/ESAs.

is using z/Architecture (64-bit real and virtual addresses).
it offers up to 640-processors in a 32 way Sysplex (512 performing workloads and up to 128 performing system and backup functions).
it supports the Linux, TPF, z/OS and z/VM and operating systems.
S/390 ESA applications are fully compatible with z/Architecture.

IBM e(logo)server zSeries 800 family :

to summarize

In May 2003,IBM announced [1] the zSeries 990 family,which began shipping at the end of that October.These models promised nearly three times the total system capacity,four times the memory,and over four times the I/O and networking bandwidth of the z900 family. The zSeries z990 Model D32 is currently the most powerful IBM mainframe computer,capable of over 9,000,000,000 instructions per second.

ZSeries

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