SCNSER - Scanner Service

This document is an assembly language listing for a "Scanner Service" program, developed by Tom Eggers and dated August 9, 1965. It outlines the low-level routines and logic for managing Teletype (TTY) and scanner interactions.

Key functionalities include:

• System Initialization: The SCNINI routine sets up the TTY system, including device data blocks (DDBs) and interrupt channels.
• TTY Management: Routines like TTYKIL, TTYDET, TTYATT, and TTYSET handle the lifecycle of TTYs, such as returning them to a virgin state, detaching them from jobs, attaching them to jobs, and initializing user TTY IOS words.
• Debugger Interaction: Modules like TTYCOM, DDTGT, DDTRL, DDTIN, and DDTOUT facilitate communication with the DDT debugger for input, output, and managing different operational modes.
• TTY Information and Search: Functions such as TTYJOB, TTYSR1, TTYFND, and DDBSRC help in identifying TTY job associations and locating available device data blocks.
• Character and Buffer Handling: Routines like GCHAR, MOVBUF, SPCIN, SCTAB, and DELET manage the processing of input and output characters, including special control characters (e.g., carriage return, line feed, tab, backspace), and handle buffer operations.
• Console Control: CTYOUT, CTYINT, and TTYDSP provide mechanisms for controlling console output and processing console-related interrupts.

The listing uses a variety of assembly instructions typical for architectures like the PDP-10, along with detailed comments explaining the purpose of code segments and register usage. It serves as a comprehensive technical reference for the program's operational logic and symbolic definitions.