Magnetic Tape Routines for 516 Control

This document provides the source code, assembly notes, and internal subroutines for managing magnetic tape operations on the 516 Control system. It includes definitions for device data blocks (DDB), error counting routines (long parity, short parity, illegal operation, data missed), and various service routines such as initialization, release, close output, input/output, and directory lookup. The document also contains comprehensive symbol tables for cross-referencing routines, memory locations, and error handling flags.