03 1973AsmRef monitorCalls

This document, "DECsystem-10 Monitor Calls" (DEC-10-MRRC-D), is a comprehensive reference manual for experienced assembly language programmers, reflecting the 5.06 release of the monitor. It details the various monitor programmed operators (UUOs) and system services available to user programs.

The manual is structured as follows:

• Memory Format (Chapter 1): Describes the organization of memory on KA10 and KI10-based systems, including memory protection, relocation, page mapping, user core storage, the Job Data Area (JOBDAT), and the Vestigial Job Data Area.
• Introduction to User Programming (Chapter 2): Introduces the three processor modes (User, User I/O, Executive) and the concept of Programmed Operators (UUOs). It explains how UUOs operate, their availability across different DECsystem-10 configurations, the CALL and CALLI operations for extending UUOs, restrictions in reentrant user programs, and naming conventions for monitor symbols.
• Non-I/O UUOs (Chapter 3): Covers monitor calls not directly related to I/O, such as execution control (starting, stopping, trapping, suspending jobs), core memory management (locking, unlocking, allocating, and segment control), program and profile identification, inter-program communication, environmental information (timing, job status, monitor examination, configuration), and real-time programming features like RTTRP (real-time trapping) and high-priority scheduler queues.

• I/O Programming (Chapters 4, 5, 6):

  • General I/O Organization (Chapter 4): Lays out the general principles of I/O programming, including device selection and initialization (INIT, OPEN, RESET), buffer management (ring buffers), file selection (LOOKUP, ENTER, RENAME), data transmission modes (buffered and unbuffered), file status checking and setting, and device termination/reassignment.
  • Nondirectory Devices (Chapter 5): Provides specific I/O programming details for various nondirectory devices like card punches/readers, console terminals, displays, line printers, magnetic tapes, paper-tape punches/readers, and pseudo-TTYs, detailing their concepts, data modes, and special services.
  • Directory Devices (Chapter 6): Focuses on I/O programming for DECtape and Disk, explaining their file structures, formats, block allocation, access protection, disk quotas, and simultaneous access. It includes detailed descriptions of special programmed operator services for advanced file and directory management (e.g., PATH, USETI, USETO, SEEK, CHKACC, STRUUO) and unit record I/O spooling.

• Monitor Algorithms (Chapter 7): Offers insight into the monitor's internal workings, covering job scheduling, program swapping strategies, device I/O optimization techniques (queuing, channel command chaining), monitor error handling, directory management, priority interrupt routines, and memory parity error analysis and recovery.

• Appendices (A-H): Provides supplementary technical reference material, including DECtape compatibility, guidelines for writing reentrant user programs, various card and magnetic tape codes, comprehensive lists of device status and error codes, a comparison of disk-like devices, and an explanation of file retrieval pointers and checksum algorithms.