Character String Typeout

Summary

This document provides technical documentation and the assembly code listing for a basic PDP-8 subroutine designed to output internal character strings. The subroutine is capable of handling all ASR-33 teleprinter characters, including special characters that conflict with standard ASCII groupings.

Key details include:

• Functionality: It processes character strings stored in memory, packed as two 6-bit characters per word. It uses a specific flag mechanism (the "00" bit code) to determine if a character is a special control character requiring unique handling.
• Requirements: The program requires 59 decimal core memory locations and is designed for a basic PDP-8 system.
• Operation: Users call the subroutine with a JMS instruction, providing the starting address of the string in the Accumulator (AC).
• Technical Approach: It utilizes internal logic to mask 6-bit codes and switches between standard printing and special character processing (e.g., EOT, WRU, BELL, etc.) by modifying internal instructions dynamically.