PDP-4 Program Library

This document describes TICTOC, a comprehensive input-output conversion package for the PDP-4 computer. It handles Teletype input and output, converting characters to a concise internal code, packing them three to a word for storage, and then converting them back to Teletype output. The package comprises four main subroutines: tic (converts and packs a string of input characters), onetic (converts a single input character), toc (types out a string of packed text), and cotoc (types out a single character from concise code).

TICTOC utilizes a table lookup for character conversion and internally manages letter/figure shifts and tabulations. While onetic can be used independently, tic requires onetic. Similarly, toc and cotoc are linked. The package addresses character set incompatibilities between FIO-DEC and Teletype by providing equivalents for Assembler and Fortran characters. It also includes useful smaller subroutines like carr (carriage return and line feed) and typit (type a character). The complete program occupies 5078 (octal) memory locations and is assembled from three tapes: "subroutines," "input," and "output."