IBM 9370

The IBM 9370 systems were "baby mainframe" midrange computers, released 1986 at the very low end of, and compatible with System/370.

The announcement described the IBM 9370 as "super-mini computer" for commercial and engineering/scientific use—compact, rack-mounted, designed for an office environment, not needing a data center to be used.

At the time of announcement the systems were positioned between the IBM System/36 / IBM System/38 and the IBM 4300 series in performance.

Intended to be sold in large amounts as departmental machines ("VAX killers"), the 9370 initially suffered from lack of software and the failure of IBM to market it properly. Nevertheless, the systems were popular at least with users actually needing System/370 compatibility while not wanting to accept the expense of a larger system (like e.g. smaller software houses) or with users (like some large IBM customers) preferring hierarchically structured distributed processing solutions rigidly managed by central communication controllers like IBM 37xx. By 1990 the 9370 line had around 6,300 installed systems and generated over 2 billion dollars in sales for IBM.

While becoming part of the Enterprise Systems Architecture in 1988 ("ES/9370" like "ES/4300" and "ES/3090"), the 9370s weren't XA systems. In 1990 IBM announced the "ES/9000" series; the rack-mounted models 120-170 with 31-bit Enterprise Systems Architecture (ESA) and ESCON were the suggested upgrades for ES/9370 users.

Initially, the lineup contained four models: 20, 40, 60, and 90.

The IBM 9370 was partially a replacement for the also-not-so-successful IBM 8100 distributed processing engine.

High-level 9370 models were mentioned as a substitution when low-level 4300 models were withdrawn from marketing 1987.

The 9370 evolved into ES/9370, which itself was complemented with, and later followed on by the ES/9221 in 1990.

During the 9370s product lifecycle, several models have been available.

The 9370 core was an IBM 801 CPU. All models included a floating point accelerator as well as a processor console to install, operate and maintain the system.

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