Decmate Ii Rom Listing

This document contains the assembly source code (listing) for the DECmate II Primary Control ROM, originally assembled on June 26, 2018, based on the file 358360.PAL.

Summary:

• Purpose: This code resides in three 2716 ROM packages (E113, E114, E115) and controls the initial power-up sequence and basic system operations of the DECmate II.
• Startup Sequence: Upon power-up, the system enables ROM control for memory references. The ROM code loads a loader program into page zero of RAM, which subsequently moves the bulk of the ROM code into CP field seven. Once the loading operation is complete, the ROM is disabled.

• Content: The document provides detailed assembly instructions, including:

  • Processor I/O and Internal I/O: Definitions for handling keyboard, screen, video interrupts, printers, and communication ports.
  • Memory Management: Logic for loading and executing code in RAM, including memory tests (verifying RAM integrity with alternating pattern checks).
  • Subroutines: Various routines for screen character output, row/register loading, printer loopback testing, keyboard input, and disk controller initialization (RX50/RX01/RX02).
  • Data Tables: Includes tables for character generator line indices and parameters for various system operations.

• Technical Details: The assembly was performed by Charles J. Lasner, with a last edit date recorded as December 2, 1991. The document includes a comprehensive symbol table at the end for reference.