AIPOS Monitor Internal Description

This document provides a detailed internal description of the AIPOS core-resident Monitor, serving as a guide for programmers developing programs for the AIPOS system. The Monitor offers device-independent I/O services and handles device-specific interrupts, allowing application programs to be written with minimal concern for hardware specifics, thereby ensuring software expandability.

Key aspects covered include:

• Data File Format: AIPOS data files comprise a header (primary and secondary blocks for file information and data format) and data blocks.
• Monitor Organization: Detailed memory allocation for various Monitor components, including resident routines, interrupt handlers, and user program areas. It highlights how the Monitor works with the Job Control Language (JCL) processor for file management and command interpretation.
• I/O Facilities: Standard calling sequences for input/output operations, comprehensive unit code assignments for various devices (e.g., LINCtape, disk, teleprinter, display), and methods for checking operation completion.
• Interrupt Facilities: Mechanisms for enabling and disabling interrupt handlers using routines like SETINT, guidelines for user-defined interrupt routines, and special handling for control characters.
• Assembly Instructions: Procedures for modifying and assembling key AIPOS system components such as the Monitor, Job Control, DORA, file handling functions, and BUILD programs.
• Internal Description of Routines: In-depth explanations of core Monitor services, including specific I/O routines (READR, WRITR, ENQ, DEQ) for different devices (LINCtape, Teletype, Display, Disk), their interrupt handlers, and the system's bootstrap loading process.
• System Maps and Flowcharts: A Monitor Core Map outlining memory usage and flowcharts illustrating critical processes like initial program load, interrupt processing, and general I/O request handling.

The document emphasizes the structured design of the AIPOS Monitor, which allows for efficient and expandable system operations.