IBM System/370
The System/370 is a model range of IBM mainframes introduced in the early 1970s as the successors to the System/360 family. New architectural features distinct from the 360 range include: standard dual-processor capability, full support for virtual memory, and 128-bit floating point arithmetic.
The 370 series of computers is a 32-bit big endian style mainframe architecture, as compared with little endian architecture such as the 80X86 series of 32-bit microprocessors.
The original System/370 line underwent two major architectural improvements during its roughly 20-year lifetime, both primarily involving expansions in memory (central storage) address space to support larger workloads, and both preserving backward compatibility. In the 1980s IBM introduced the 370/XA architecture as the first step in the upgrade from 24-bit to 31-bit addressing (IBM reserved one bit to facilitate backward compatibility). In the 1990s IBM introduced 370/ESA architecture (later named 390/ESA), finishing the evolution to full 31-bit virtual addressing.
The System/390 line replaced the System/370s in the 1990s.
Notable machines in the 370 range include the IBM 3033, the IBM 3090 mainframe/supercomputer with its optional vector facility (VF) extension, and the relatively inexpensive IBM 9370 (tailored for small-to-medium size businesses). Amdahl Corporation competed aggressively against IBM with its IBM-compatible mainframes.
System/370 is often abbreviated S/370, and the GNU Compiler Collection had a Backend for S/370, but it had become obsoleted over time and finally replaced by the S/390 backend for Machines supporting the instruction set of System/390 Generation 5 (G5) which was the hardware platform for the initial release of Linux/390.