Teletype Output Package

This document describes the Digital-7-10-0 Teletype Output Package, a set of subroutines for the PDP-7 computer designed to facilitate typing characters and formatting output on a teletype.

Key features and functionalities include:

• Subroutines for character output: TDIGIT (for digits), TY1 (single character from AC), TY3 (three characters from AC), and TSR (string of characters).
• Formatting routines: TCR (carriage return and line feed), TSP (space), TYT (tabulation), and TIN (teleprinter initialization, including setting to lower case and resetting character count). TIN should be called before other routines.
• User-supplied routine: The package requires the user to provide an OTY subroutine for typing out a single teletype character. Suggestions for OTY are provided for both interrupt and non-interrupt driven I/O programs.
• Character encoding: Routines assume 6-bit character codes, where the leftmost five bits are the Baudot code and the rightmost bit indicates upper or lower case (for Type 28 Teletype). When using a KSR33 (Type 33 Teletype), 5-bit codes are translated to 8-bit ASCII codes.
• Case handling: For Type 28 Teletypes, the routines attempt to manage keyboard case shifts. A warning is given regarding potential desynchronization if the user also uses the keyboard for input and changes the case without updating the package's internal indicators.

The document also includes a program listing of the Teletype Output Package code.