ONCER Once Only Operator Dialogue And I/O Device Init. (Burroughs Disk)

This document details "ONCER" (Once Only Operator Dialogue and I/O Device Initialization), a MACRO assembly program copyrighted in 1969 by Digital Equipment Corp. It is designed to be the final program loaded before system utilities like SYSMAK and DOT, intended for PDP-10 (Burroughs Disk) or older PDP-6 (Data Products Disk) systems.

The program's core function is to initialize the system and configure I/O devices. This involves several key areas:

• System Initialization: Setting up priority channels, interrupt service routine chains, and relocation registers.
• Memory Management: Moving the symbol table, finding non-existent memory, and allocating memory for device data blocks.
• Operator Dialogue: Interacting with the user to obtain system parameters such as the current date and time, and to specify the operator's console.
• Disk Configuration: Conducting a detailed "refresh dialogue" with the operator to set up disk drives, including determining disk capacity, configuring swap space (1K blocks), specifying Master File Directory (MFD) and System Address Table (SAT) block locations, and checking write-lock switch settings.
• Data Management: Computing and storing checksums for the monitor and disk data, writing vital statistics, MFD, and SAT information to disk, and handling various error conditions during these processes.

The code is structured into mandatory, usual, and optional parts, allowing for flexible system startup, debugging, and disk maintenance. It includes dedicated routines for console input/output and ensuring data consistency across different system configurations.