Uuo Handler

This document is an assembly listing for a "UUO Handler" (Unimplemented User Operation Handler), likely part of a SYSCON (System Console) component. It details the logic and routines for processing various types of UUOs within a system.

The handler classifies UUOs into three main categories:

1. System Functions: These involve operations like loading ACS (Accumulator Switch) PDP (Programmed Data Processor) and program dispatch.
2. Device Independent I/O UUOs: These handle I/O operations without being tied to specific hardware.
3. Device Dependent I/O UUOs: These are specific to particular devices and involve dispatching based on device information.

Key aspects of the handler include:

• UUO Processing Flow: UUOs are initially directed to specific memory locations (40 and 41) and then processed. If not a system UUO, they are relocated to user space.
• Error Handling: Mechanisms are in place for detecting illegal UUOs or calls from interrupt service routines, which are restricted.
• Monitor Interface: The document specifies routines called (e.g., ILLINS, ADRCK, EXCLK, UUOH) and symbols used, along with data structures like Job Area and System Addresses.
• Internal Routines: Sections are dedicated to internal UUO processing, including saving/restoring registers, handling user mode entries, and dispatching to specific routines based on UUO op-codes.
• System Call (UCALL): A routine for calling system functions by name, involving searching a system routine table (UCLTAB).
• Exit Handler (UXIT): Routines for returning control from a UUO call, restoring accumulators and system state, and distinguishing between system and user mode exits.

The document also provides an extensive symbol table, listing internal and external variables and routines referenced throughout the assembly code. The code includes creation dates for the handler (3/10/65) and UCALL (64-11-17).