ACOS-4/NPX (which stood for “new parallel extended”) was an operating system designed for NEC’s mid-size and large mainframes. NEC announced and started shipping the operating system in April 1998.

ACOS-4/NPX was designed to be an operating system that underpinned enterprise information systems for the Web computing age, in which the Internet was the core communication medium. With this goal in mind, ACOS-4/NPX supported standard Web protocols, provided security management infrastructure, and offered high-speed data connectivity and bidirectional operational connectivity with open systems. The operating system was installed on the PX7600SV and PX7800SV Parallel ACOS mainframes, which were announced in October 1998.

The main features of the operating system are given below.

Figure 1: Main strengths of ACOS-4/NPX

Figure 1: Main strengths of ACOS-4/NPX

1. Network connectivity
As well as adding support for distributed object technology, security, and other new technologies, ACOS-4/NPX provided network connectivity functions that were the central pillars of the Web computing age.
(1) Support for the standard CORBA protocol
ACOS-4/NPX included the latest distributed object technology and provided the basic functionality for building platform-independent systems. Smooth connections between multiple platforms were realized with the support of global standard protocols, such as CORBA.
Parallel ACOS machines used a wrapping technique to support the CORBA protocol. This meant that open servers could access as CORBA objects the many existing services accumulated on Parallel ACOS machines so that existing Parallel ACOS assets could continue to be used effectively.
(2) Security management infrastructure
NEC provided SecureGlobe, a total security solution to guarantee the authenticity and security of data flying around networks and to construct stable usable network systems. The goal was to construct secure systems that did not sacrifice user convenience by continually providing consistent security products and technologies based on a unified product concept and product architecture.
With the Parallel ACOS, NEC again took this concept and provided a security management infrastructure of encryption, user authentication, and other features that were compliant with industry standard security functions.
  • The encryption function encrypted communicated data to protect information confidentiality
  • The public-key authentication methodology prevent connections from unauthorized parties

2. Data and operational connectivity with open systems
ACOS-4/NPX included functions provided high-speed data connections and bidirectional operation connections with UNIX and other open servers.
(1) Data connectivity through disk sharing
This function provided a disk between the Parallel ACOS machine and the open server and passed data at high speeds via a fiber channel arbitrated loop (FC-AL), a high-speed optical loop.
The operating system provided the same functionality for file access from open servers as for access with a Parallel ACOS machine, including sharing and exclusive access control over files, access privilege verifications, automatic switchover on file path obstructions, and access blocking functions. This level of security was suitable for very high mission-critical systems and data.
(2) Bidirectional operational connectivity
ACOS-4/NPX provided the functionality for mixed systems consisting of UNIX or other open servers and Parallel ACOS machines to monitor at one station the operating status of all types of servers and to connect operations in both directions. Comprehensive monitoring and bidirectional operations were realized through communications with a dedicated browser on a UNIX server. Some of the key functions were:
  • An operation monitor function that allowed the UNIX browser display Parallel ACOS console messages and send console commands
  • An event communication function that used messages to communicate events between different platforms
  • A power-supply control function that allowed the UNIX browser to turn the Parallel ACOS machines power supply on or off

Cover of the NEC ACOS-4/NPX manualPage from the NEC ACOS-4/NPX manual