IBM System/390

The ESA/390 was succeeded by the 64-bit z/Architecture in 2000. The architecture (the Linux kernel architecture designation is "s390"; "s390x" designates the 64-bit z/Architecture) employs a channel I/O subsystem in the System/360 tradition, offloading almost all I/O activity to specialized hardware. It was the successor of Enterprise Systems Architecture/370 (ESA/370) and, in turn, was succeeded by the 64-bit z/Architecture in 2000.

z/Architecture, initially and briefly called ESA Modal Extensions (ESAME), is IBM's 64-bit instruction set architecture implemented by its mainframe computers.

ESA/390 (Enterprise Systems Architecture/390) was introduced in September 1990 and was IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors.

Prominent 32-bit instruction set architectures used in general-purpose computing include the IBM System/360 and IBM System/370 (which had 24-bit addressing) and the System/370-XA, ESA/370, and ESA/390 (which had 31-bit addressing), the DEC VAX, the NS320xx, the Motorola 68000 family (the first two models of which had 24-bit addressing), the Intel IA-32 32-bit version of the x86 architecture, and the 32-bit versions of the ARM, SPARC, MIPS, PowerPC and PA-RISC architectures.

Multiple Virtual Storage, more commonly called MVS, was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers.

ESA/390 (Enterprise Systems Architecture/390) was introduced in September 1990 and was IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors.

The System/360 later evolved into the System/370, the System/390, and the 64-bit zSeries, System z, and zEnterprise machines.

ESA/390 (Enterprise Systems Architecture/390) was introduced in September 1990 and was IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors.

The first generations of IBM's CMOS mainframe processors, the IBM 9672 G3 and G4, could not perform as well as those from the Enterprise System/9000 family, which were based on bipolar technology, giving Amdahl a temporary advantage.

The ESA/390 was succeeded by the 64-bit z/Architecture in 2000. It was the successor of Enterprise Systems Architecture/370 (ESA/370) and, in turn, was succeeded by the 64-bit z/Architecture in 2000.

ESA/390 (Enterprise Systems Architecture/390) was introduced in September 1990 and was IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors.

In the 1990s IBM introduced 370/ESA architecture (later named 390/ESA and finally ESA/390 or System/390, in short S/390), completing the evolution to full 31-bit virtual addressing and keeping this addressing mode flag.

Under Linux/390 this memory cannot be used for disk caching; instead, it is supported by a block device driver, allowing to use it as ultra-fast swap space and for RAM drives.

Linux on IBM Z originated as two separate efforts to port Linux to IBM's System/390 servers.

Expanded Storage can be used for ultra-fast paging, for disk caching, and for virtual disks within the VM/CMS operating system.

VM (often: VM/CMS) is a family of IBM virtual machine operating systems used on IBM mainframes System/370, System/390, zSeries, System z and compatible systems, including the Hercules emulator for personal computers.

The architecture (the Linux kernel architecture designation is "s390"; "s390x" designates the 64-bit z/Architecture) employs a channel I/O subsystem in the System/360 tradition, offloading almost all I/O activity to specialized hardware.

In IBM ESA/390 terminology, a channel is a parallel data connection inside the tree-like or hierarchically organized I/O subsystem.

The Hercules emulator is a portable ESA/390 and z/Architecture machine emulator which supports enough devices to boot many ESA/390 operating systems.

Hercules is a computer emulator allowing software written for IBM mainframe computers (System/370, System/390, and zSeries/System z) and for plug compatible mainframes (such as Amdahl machines) to run on other types of computer hardware, notably on low-cost personal computers.

In addition, a machine may be divided into Logical Partitions (LPARs), each with its own system memory so that multiple operating systems may run concurrently on one machine.

IBM began marketing its functionally similar PR/SM in 1988, implemented on its ESA/390 architecture released that year.

It was the successor of Enterprise Systems Architecture/370 (ESA/370) and, in turn, was succeeded by the 64-bit z/Architecture in 2000.

In September 1990, the System/370 line was replaced with the System/390.

(IBM reserved the most significant bit to easily support applications expecting 24-bit addressing, as well as to sidestep a problem with extending two instructions to handle 32-bit unsigned addresses.)

Some architectures like SPARC and Motorola 68000 use "LSB 0" bit numbering, while S/390, PowerPC and PA-RISC use "MSB 0".

The architecture (the Linux kernel architecture designation is "s390"; "s390x" designates the 64-bit z/Architecture) employs a channel I/O subsystem in the System/360 tradition, offloading almost all I/O activity to specialized hardware.

(The idea of a major breakthrough with FS technology was dropped in the mid-1970s for cost-effectiveness and continuity reasons.) Later compatible IBM systems include the 4300 family, the 308x family, the 3090, the ES/9000 and 9672 families (System/390 family), and the IBM Z series.

These systems followed the IBM 3090, with over a decade of follow-ons.

The eight largest of the 18 models of the ES/9000 systems introduced in 1990 were water-cooled; the other ten were air-cooled.

Some PC-based IBM-compatible mainframes which provide ESA/390 processors in smaller machines have been released over time, but are only intended for software development.

In 1995 IBM introduced a card, the "Enhanced S/390 MicroProcessor Complex", which supported IBM ESA/390 architecture on a PC-based system.

By the late 1970s and early 1980s, patented technology allowed Amdahl IBM-compatible mainframes of this era to be completely air-cooled, unlike IBM systems that required chilled water and its supporting infrastructure — the 8 largest of the 18 models of the ES/9000 systems introduced in 1990 were water-cooled; the other ten were air-cooled.

Logical Partitions (LPARs) are a standard function on ES/9000 processors whereby IBM's Processor Resource/Systems Manager (PR/SM) hypervisor allows different operating systems to run concurrently in separate logical partitions (LPARs), with a high degree of isolation.

IBM provides virtualization partition technology known as logical partitioning (LPAR) on System/390, zSeries, pSeries and iSeries systems.

CMOS designs permitted much smaller mainframes, such as the Multiprise 3000 introduced in 1999, which was actually based on 9672 G5.

The main processors are the same CMOS chips used in the G5 series of IBM 9672, the flagship S/390 systems.

ESA/390 (Enterprise Systems Architecture/390) was introduced in September 1990 and was IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors.

ESA/390 (Enterprise Systems Architecture/390) was introduced in September 1990 and was IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors.

ESA/390 (Enterprise Systems Architecture/390) was introduced in September 1990 and was IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors.

The 9672 implementations of System/390 were the first high-end IBM mainframe architecture implemented first with CMOS CPU electronics rather than the traditional bipolar logic.