Fred

This document serves as a technical handbook for "FRED" (File Replacement, Entry, and Deletion), a set of PDP-12 subroutines designed to manipulate LAP6-DIAL indices.

Key aspects of the document include:

• Overview and Environment: FRED occupies two tape blocks and utilizes four LINC memory blocks when loaded. It provides a structured set of routines for managing files on DIAL tapes.

• Routine Descriptions: The handbook details the functionality and calling sequences for several major routines:

  • GETFLD: Obtains the address of the user's parameter list.
  • READ/WRITE: Handles data input/output operations.
  • LOOKUP: Searches the DIAL index for a specified file.
  • ENTER: Adds a new file entry to the index.
  • REPLACE: Replaces an existing file entry.
  • FCF (Conflict Search): A utility routine that scans the index for potential file space conflicts.
  • DELETE: Removes a file from the index and manages the necessary index updates.

• Technical Details: The document provides extensive technical notes, including entry points, parameter list structures, and register definitions, alongside flowcharts and the program's assembly code listings to assist developers in implementation and troubleshooting.