comcon

The "COMCON - COMMAND DECODER AND SAVEGET ROUTINES" (v433, 1969) is a core component for managing console commands and job-related routines in a PDP system.

Its primary functions include:

1. Command Interpretation and Dispatch: It receives commands from TTY services, parses the input, matches it against a comprehensive command table (COMTAB), and dispatches to specific setup routines for each command (e.g., START, HALT, ASSIGN, SAVE, RUN).
2. Job Management:
   • Lifecycle Control: Handles starting, stopping, re-entering, and continuing jobs, with provisions for quick execution or delayed processing if resources are unavailable.
   • Resource Allocation: Manages the assignment and deallocation of job numbers, core memory (including handling compressed core and high/low segments), and logical devices.
   • Status and State Checks: Performs extensive pre- and post-dispatch checks on job status, login state, active devices, memory availability, and swapping conditions.
3. TTY and Console Interaction: Manages input parsing (ignoring spaces, tabs, etc.), output formatting (e.g., printing job numbers, system configuration, times), setting TTY modes, and handling break characters.
4. Error Handling: Incorporates robust error checking for various scenarios, such as illegal commands, exceeded job capacity, login failures, core allocation issues, device assignment conflicts, and unexpected input. It includes routines for printing error messages and re-queuing commands.
5. System Information and Status Reporting: Provides functionality to display system status, job running times (incremental and total), available resources, file system details, and configuration information.
6. Internal Structure: Relies on defined bit flags and dispatch tables (DISP) to efficiently encode and manage command properties, resource requirements, and post-execution behaviors.

The system is designed to operate within a clock-driven environment, emphasizing quick execution of command setup routines or deferring complex operations to ensure system responsiveness.