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The CAPS-8 Operating System

Introduction

The PDP-8 Cassette Programming System (CAPS-8) is a small programming system for the PDP-8/E, /E, /F computers and is designed around the use of cassette tapes for program storage rather than DECtape, paper tape or disk storage. This replaces paper tape procedures completely. The MI8-E Hardware Bootstrap initially loads the Cassette Keyboard Monitor into memory. The Monitor manages transfers and program loading via cassette. CAPS-8 provides the user with a Keyboard Monitor, I/O facilities at the Monitor level and a library of System Programs including an Assembler (PALC), an editor, and a higher-level programming language (BASIC). OS/8 utilities could manipulate CAPS-8 cassettes. A derivative operating system (CAPS-11) was available for the PDP-11. The file format on a CAPS-8 cassette is compatible with CAPS-11.

Software Components

Following is a brief description of the CAPS-8 software package. Each program is described in more detail within the USer Manual.

  • MONITOR -- The Keyboard Monitor provides communication between the user and the Cassette System Executive Routines by accepting commands from the console terminal keyboard. The commands allow the user to run system and user programs, save programs on cassette, and obtain directories of cassettes.
  • Symbolic EDITOR - The EDITOR allows the user to modify or create source files for use as input to language processing programs such as BASIC and PALC. The EDITOR contains powerful text manipulation commands for quick and easy editing.
  • PALC Assembler (Program Assembly Language Cassette) PALC accepts source files in the PAL machine language and generates absolute binary files as output. These files can then be loaded and executed using Monitor commands.
  • BASIC - BASIC provides a higher-level programming language which is easy to learn and use. It includes such language features as user-coded functions, data files on cassette, and program chaining.
  • System Copy (SYSCOP) - SYSCOP allows the user to transfer files from one cassette to another, providing the ability to make multiple copies of a cassette and "clean up" full cassettes so that they may become available for future use.

Hardware Configuration

CAPS-8 requires a PDP-8/E, /M, or /F computer with a minimum of one TU60 dual cassette tape unit, a console terminal (LA30 DECWriter, LT33 or LT35 Teletype, or VT05 DECterminal), and 8K of memory. A line printer is supported but is optional.

Please refer to the Software Documentation page here for more information on CAPS-8.