680 8-Bit Character Assembly Subroutines

This document covers the 680 Data Communication System 8-Bit Character Assembly Subroutines (Digital-8-35-S-B). These subroutines are designed to accumulate 8-bit Teletype characters to and from multiple Teletype lines connected to a PDP-8. The document outlines storage requirements, necessary hardware configuration, and the specific pseudo-commands (T8INIT, T8SOF, T8SIR, T8SIE) required to interface with the subroutines from a main program. It also provides information on interrupt service routine implementation, execution times, detailed program listings, and flow charts for initialization, output, and input handling.