System/390 (also S/390) is a large computer architecture of the company IBM. She was presented 1990.

This concerns the follow-up series to the System/370. It is well-known in their current 64-Bit-Variante as zSeries.

IBM made available in the course of the 90's servers in altogether 6 generations (G1 to G6) the S/390-Architektur. The first generations used still bipolar transistors in the CCUs, while the CCUs of the later generations were based on CMOS technology. Also the function range (instruction set) of the CCUs was extended in the course of these generations, e.g. a IEEE-compatible floating decimal point arithmetic and logic unit became only with the G5-CPUs imported.

CMOS-based CCUs were connected in the servers manufactured by IBM in multi-chip modules so mentioned (MCM) on a Keramikplatte with Cache memory and I/O interface to a processor module. The smallest this MCMs are into the multi-prize 3000-Modellen (G5) with three CCUs, while the MCMs of the large models accommodates 14 CCUs.

S/390-CPUs are divided into different groups:

• PU (Physical unit): A physically existing CCU, PUs are dedicated assigned to different purposes:
  • CP (cent ral Processor): For the execution from user programs to the order standing PU. If the machine were started with the POR (power on RESET) in the LPAR mode, can be used with the configuration by logical partitions of the machine two kinds by CPs:
    • Dedicated: Dedicated CP - stands to 100% only for this logical partition for order
    • Shared: Together Genutzer CP - can be used, together with other logical partitions
  • SAP (system ASSist Processor): Dedicated PU for the execution of I/O
  • Save CCU: A task, cannot transfer assigned PU automatically its function in the case of the defect of a CPs or a SAP
• CCU: On a CP (dedicated or shared) under VM/ESA (current product: z/VM) virtual CCU administered. CCUs are not assigned CP. More virtual CCUs can be put to the individual virtual servers under VM/ESA at the disposal than PUs are present and such VM-Guest to be able far (up to 32) CCUs are attacht, which the guest system can use directly without restart of the guest system.

S/390-basierte and/or S/390-kompatible of systems were manufactured also by the IBM competitors Hitachi and Siemens, whereby these machines themselves differ in hardware details, which concern also device drivers, from the IBM-S/390 servers.

Emulators:

• FLEX-ES, very efficiently, i386-spezifisch, commercial product
• Hercules, platform-neutrally, open SOURCE, emulates also the z/Architecture (ESAME), the 64-bit follow-up architecture of S/390, the computer architecture IBM zSeries servers, compatible to S/390.

Related links

• IBM S390 parallel Enterprise of server

Articles in category "System/390"

We found here 6 articles.

Related Websites

We found here 2 related websites.

• ESA/390 - Wikipedia, the free encyclopedia
  Machines supporting the architecture have been sold under the brand System/390 or S/390 for short, and underwent 6 generations from the beginning to the end ...


• IBM eServer zSeries - Wikipedia, the free encyclopedia
  The IBM eServer zSeries line succeeded the IBM System/390 (S/390 for short) which were based on the ESA/390 architecture while ensuring full compatibility ...