Dial-MS Editor Program Description

This document describes the DIAL-MS Editor, a comprehensive program designed for the PDP-12 computer that functions as an editor, filing system, and assembler. It is largely derived from the basic LINC program LAP6 by Mary Allen Wilkes and incorporates assembly portions from PDP-8 programs like PAL-D. The Digital Equipment Corporation acknowledges Mary Allen Wilkes for her contributions to LAP6.

The DIAL-MS Editor combines features from the DIAL-V2 Editor (DEC-12-ZW7A-D) and the DIAL-V2 Add Program (DEC-12-ZW8A-D), maintaining logical and functional similarity but utilizing DIAL-MS routines for all I/O operations. It allows users to create, modify, and edit source programs, displays line numbers and an editing cursor, and processes monitor commands. Commands referencing the "Working Area" are routed through a GOODY subroutine for logical transformation into DIAL-MS calls.

Key components and functions of the Editor include:

• System Parameters: Defines the DIAL system's configuration and nature through various editor symbols (e.g., APTBLK, ASTBLK, DIALST, WA, MAXNUM) and symbolic character codes (e.g., AM for Alt Mode, CR for Carriage Return).

• Editor's Tables: Several tables manage core functionalities:

  • Control Table: Facilitates locate requests and maps line numbers to tape blocks.
  • Grid Table: Stores bit configurations for character display (DSC).
  • Keyboard Input Conversion Table: Processes special and illegal DIAL characters from keyboard input.
  • Monitor Command Table: Decodes monitor commands and dispatches calls to subroutines.
  • Special Character Table: Identifies characters that trigger special editor commands.
  • Monitor Command Parameter Table: Stores arguments for monitor commands.
  • Tab Table: Used by scope routines for tab display formatting.

• Monitor Command Decode Routines: Detail how the Editor processes user commands entered via the carriage return, dispatches them based on their type, and sets up corresponding parameters.

• Editor Pointer Tape Block: A dedicated tape block (320) used to store and retrieve the Editor's pointers upon startup, initialization, or exit, preserving the Editor's state without a full core image.
• Input Buffers: Consist of buffer, working, and continuation memory blocks (MBLKs) in LDF 1, used for all editing and display. A "void" area between working and continuation MBLKs allows efficient editing.
• Editor's Pointers: Critical Beta registers (2-6) and other core locations (BBTBLK, CURLN, CURPTR, MAXLN, etc.) manage memory addresses and operational states.
• Add Program: A dedicated subroutine that allows users to add programs to the Working Area by name or block number, handling retrieval, character transfer to the Editor's buffers, and managing line number arguments and tape updates. It resides in tape block 321 and memory locations 5400-5777 and is an integral part of the Editor's functionality.