NDOS was the OS for HITAC 8250, and was developed for users of small to medium machines with main storage sizes generally ranging between 32 KB and 64 KB.
NHitachi announced NDOS in July 1972, and started shipping it in February 1973.
NDOS had the following features:
Various operation modes
Provides three job execution modes: single processing, continuous processing and spool processing, in order to support various operation modes, from an open system to a closed system of center-operation type.
Achieves increased operability through various ideas for efficient system operation:
- Adoption of a console display
- Reduction of parameters
- Inline space allocation of disc files
- Skip control of job steps
A rich selection of language processors
Provides language processors: assembler, RPG, COBOL, FORTRAN and PL/I in order to adapt to various business processing operations.
Real-time processing support functions
Provides various functions in order to create online programs at lower cost, faster and easier:
- General-purpose package for real-time processing (TMSI)
- Communication I/O simulation function
- Off-line seek function
- Multitask control function
- Program creation function with a reentrant structure
- Roll out/in function
Consideration of center operation
Supports functions for smooth center operation:
- Support for system files for center management such as a billing file, a console screen saving file and a fault file.
- Support for private libraries and public libraries
- Job ending function
A rich selection of utility programs
Provides utility programs for volume maintenance, file maintenance, library maintenance, linkage editor, sort/merge and debugging support.
Figure 1 shows the software configuration for HITAC 8250. As indicated in the figure, the OS also provided extensive application packages, including those for online processing, databases, numerical computation, statistic computation and graphic processing.
Figure 1 "Software configuration for HITAC 8250"
HITAC 8250 NDOS was used not only by small to medium machine users, but also as a remote batch station. Figure 2 shows an example of a computer network system where HITAC 8250 is incorporated as a remote batch station.
Figure 2 "Example of a computer network system"
RESP (Remote Batch Station Program) was a general-purpose program that sent a large-load job input from a child computer to a remote parent computer, which processed the job at high speed and returned the result to the child computer, with a large computer such as HITAC 8700/8800 or HITAC M-160II/170/180 serving as the parent computer and HITAC 8250 as the child computer.
RMT (Remote Batch Program) was a general-purpose program that processed a job from a grandchild computer using HITAC 8250, which returned the result to the grandchild computer, with a mini computer 20/10II serving as the grandchild computer.
Online control general-purpose package TMS-1 (Transaction Management System-1) was a program package that executed complex processing tasks, which had formerly made the construction of online systems difficult, in place of a user program, including control of circuits and terminals, queuing of transactions, buffering, journal acquisition and recovery processing.