System / 390
System / 390 (also S / 390 ) is the name for a family of mainframes built according to the IBM ESA / 390 (Enterprise Systems Architecture / 390) from IBM . It was presented in 1990.
System description
It is the successor series to the System / 370 . In its current 64-bit variant, it is known as System z .
In the course of the 1990s, IBM made servers available in a total of six generations (G1 to G6) of the S / 390 architecture. The first generations still used bipolar transistors in the CPUs , while the CPUs of the later generations were based on CMOS technology. The range of functions (instruction set) of the CPUs has also been expanded over the course of these generations, e.g. For example, an IEEE -compatible floating point unit was only introduced with the G5 CPUs.
In the servers manufactured by IBM, CMOS-based CPUs were connected to a processor module in so-called multi-chip modules (MCM) on a ceramic plate with cache, memory and I / O interfaces. The smallest of these MCMs are in the Multiprise 3000 models (G5) with three CPUs, while the MCMs of the large models accommodate 14 CPUs.
S / 390 CPUs are divided into different groups:
- PU (Physical Unit): a physically available CPU, PUs are assigned to different purposes:
- CP (Central Processor): PU available for executing customer programs. If the machine was started in LPAR mode with POR (Power-On Reset) , two types of CPs can be used when configuring the logical partitions of the machine:
- Dedicated: Dedicated CP - 100% only available to this logical partition
- Shared: shared CP - can be used together with other logical partitions
- SAP (System Assist Processor): Dedicated PU for the execution of I / O
- Spare CPU: PU not assigned to any task, can automatically take over its function in the event of a defect in a CP or SAP
- CP (Central Processor): PU available for executing customer programs. If the machine was started in LPAR mode with POR (Power-On Reset) , two types of CPs can be used when configuring the logical partitions of the machine:
- CPU: virtual CPU managed on a CP (dedicated or shared) under VM / ESA (current product: z / VM ). CPUs are not assigned to any CP. More virtual CPUs can be made available to the individual virtual servers under VM / ESA than there are PUs, and further (up to 32) CPUs can be assigned to such a VM guest, which the guest system can use directly without restarting the guest system.
S / 390-based or S / 390-compatible systems were also manufactured by the IBM competitors Hitachi and Siemens , although these machines differ from the IBM S / 390 servers in terms of hardware details, including device drivers .
Emulators
- FLEX-ES , very efficient, i386-specific, commercial product
- Hercules , platform-neutral, open source , also emulates the z / Architecture (ESAME), the S / 390-compatible 64-bit successor architecture of S / 390, the computer architecture of the IBM System z servers.
Web links
Individual evidence
- ↑ http://publib.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/DZ9AR006/1.1?DT=19990630131355 Enterprise Systems Architecture / 390 Principles of Operation. IBM Publication No. SA22-7201. Retrieved September 17, 2007.