ACOS-6/NVX PX (which stood for “parallel extended”) was an operating system designed for NEC’s large mainframes. NEC announced the operating system in March 1996 and started shipments in December 1996.

ACOS-6/NVX PX was an operating system for large and very-large mainframes that supported software resources from the previous large mainframe operating system ACOS-6/NVX while implementing parallel processing technology using the high-performance CMOS processors on the System PX7900, a Parallel ACOS mainframe that was released at the same time as the operating system. ACOS-6/NVX PX was installed on System PX7900 machines.

The main features of the operating system and its new architecture are given below.

1. Architecture features
(1) Use of single-chip CMOS processors
The symmetric multi-processing (SMP) structure, consisting of as many as eight memory-sharing CMOS processors, improved the system throughput by using parallel processing.
(2) Base parallel-processing technology for the operating system
The mechanism that assigned CPUs to jobs (parallel dispatching) maximized CPU cache efficiencies and minimized main memory access competition among processors.

2. Operating system features
(1) Parallel batch function / parallel file access function
The parallel batch function divided batch job steps that would normally be processed sequentially into job steps that could be processed in parallel and executed the job steps on multiple processors. When the job steps were completed, it combined the job steps’ processing results. The parallel file access function controlled the tracking of the input process position and output process position in a sequential file so that multiple job steps in a parallel process could execute inputs and outputs to the same sequential file.

Figure 1: Parallel batch function

Figure 1: Parallel batch function

(2) Parallel OLTP functions
ACOS-6/NVX PX provided two functions for high-traffic online transaction services to make efficient use of the computing power of multiple machines. The service-distribution function automatically assigned transactions with the OLTP monitor according to the service that originated the transaction, and the load-distribution function assigned transactions depending on the loading at each host.

Figure 2: Parallel OLTP

Figure 2: Parallel OLTP

(3) Open link facilities (OLF) for open system connectivity
ACOS-6/NVX PX made it possible to continue to use host computer resources in open system environments by updating and systemizing the five open connectivity functions from the previous ACOS-6/NVX operating system.

i. Transaction connectivity (OLF/TP)
Linked transaction monitors on ACOS-4 (VISII), UNIX, and Windows and made them accessible from a GUI on Windows client machines
ii. Database connectivity (OLF/DB)
Supported transfers to databases on UNIX and Windows (ORACLE) and an API (ODBC) that gave access to host databases from Windows environments.
iii. File connectivity (OLF/FL)
A remote file server accessible from open systems
iv. Delivery connectivity (OLF/DL)
Delivery of records to printers within open systems and collection of records from UNIXv
v. Job connectivity (OLF/JB)
NQS server that accepts job inputs from UNIX

Cover of the NEC ACOS-6/NVX PX manualPage from the NEC ACOS-6/NVX PX manual