OS / 8

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OS / 8 was an operating system for Digital Equipment's (DEC) PDP-8 computer . The system allowed the use of a large number of peripheral devices and used the entire core memory of 32 KB.

OS / 8 was used under the real-time system RTS-8 as a background module to enable file processing and program development in addition to real-time applications in the background. Without RTS-8, OS / 8 was used as the operating system with only 8 KB memory requirements for program development.

construction

OS / 8 consists of a kernel and a library of system programs.

The core consists essentially of 4 elements:

  • the keyboard monitor,
  • the command decoder,
  • the USR (User Service Routine),
  • the I / O device drivers.

The library of system programs is accessed via the keyboard monitor. This consists of:

Concise Command Language (CCL)
CCL provides the user with a large number of terminal commands. Typical commands are: COPY, DIRECTORY, HELP, RENAME, LIST, DELETE etc.
Symbolic Editor (EDIT)
EDIT is used to create and maintain source code that can then be translated in compilers such as PAL8, SABR or FORTRAN.
PAL8 assembler
PAL8 is the assembler of the OS / 8 system. PAL8 accepts source code in PAL language and generates binary code. In addition, PAL8 generates lists that can be processed in CREF.
Peripheral Interchange Program (PIP)
With PIP files are transferred between the devices that are present in the OS / 8. There are commands for files and directories.
Absolute Binary Loader (ABSLDR)
ABSLDR loads binary files created with PAL8 into main memory.
Octal Debugging Technique (ODT)
ODT is a powerful troubleshooting program.
File-Oriented Transfer Program (FOTP)
FOTP allows the transfer of files and file groups between devices with an OS / 8 file structure. In this way, ASCII files can be transferred between DECTape and hard drive with one command.
Cross Reference (CREF)
CREF works with the lists of PAL8 and SABR. It generates numbered lists and a table in which all jump addresses and field names are sorted.
DIRECT
DIRECT allows the user to print extended directory lists.
BOAT
The BOOT program loads the standard drivers into RAM.
Cassette / Magtape Positioner (CAMP)
CAMP allows access to cassette and magnetic tape.
Resources (RESORC)
RESORC integrates the system tables and prints a list of the active drivers.
Magtape / Cassette PIP (MCPIP)
MCPIP is a file transfer program for cassette and magtape.
PIP10
PIP10 is a file transfer program that allows reading and writing of PDP-10 ASCII files from the DECTape using the TC8 or TD8E controller.
FORTRAN II
The OS / 8 system contains a powerful FORTRAN package, consisting of the FORTRAN compiler, SABR assembler, link loader and library functions. Some of the benefits of Fortran are:
  • FORTRAN II is easy to use. FORTRAN source programs can be compiled, loaded and started with one command.
  • Loops are allowed in FORTRAN II.
  • Programs can be linked in FORTRAN II. This allows an efficient program structure.
  • There is a device-independent input / output structure for console, fast reader / punch and printer.
Library setup (LIBSET)
OS / 8-LIBSET allows you to create your own program libraries. The LB8 standard library is supplied with OS / 8. With LIBSET you can write your own routines in SABR and create a library.
System Build (BUILD)
BUILD allows the device configuration in the system to be changed easily. New devices can be added with simple commands.

Other programs

In addition to the standard programs, there are the following programs, where BASIC, BATCH and TECO were supplied in an expansion kit.

  • OS / 8 BASIC is an interactive language with a range of uses. It contains options for chaining, text editing and file-oriented input and output. BASIC also contains some functions for use in LAB / 8E.
  • OS / 8 BATCH gives the user the option of batch processing, which is integrated in the OS / 8 monitor structure. The system is designed to be used either from the keyboard or for batch processing. BATCH can be used to enter the commands from punched cards, punched tape or an OS / 8 system device.
  • OS / 8 TECO is a text editor that runs under the OS / 8 operating system. With TECO you can edit any ASCII text such as programs, manuscripts, correspondence, etc.
  • OS / 8 FORTRAN IV offers the full ANSI FORTRAN IV under the OS / 8 operating system. The system is optimized for low memory requirements and includes the overlay option, which allows programs of 300 KB to run in the virtual memory of the PDP-8 or PDP-12. The library functions allow access to laboratory equipment, to transcendent functions, processing of text and output on standard increment plotters.

Device driver

OS / 8 is completely device-independent. First, programs can be written on a PDP-8 computer without accessing special I / O devices. While the program is running, the user can select most of the available devices. In addition, the program does not have to be rewritten if the configuration of the computer changes.

The OS / 8 system controls the transfer of data from one medium to another by calling the appropriate I / O routines. Devices can be given logical names to enable symbolic access.

Variable I / O buffers can be defined in the program. Large buffers ensure efficient operation of the storage units without having to spend a lot of time on disk / tape movements. OS / 8 uses all the possibilities of the RK8E disk storage, but can also run from a single DEC tape.

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