Symbolic Tape Editor

This document describes the Symbolic Tape Editor for the Programmed Data Processor-7 (PDP-7) computer, which is also compatible with the PDP-4. Its primary purpose is to simplify and accelerate the debugging process by allowing programmers to correct symbolic programs more efficiently. The Editor works by reading sections of symbolic tape into a core memory "text buffer" for examination and modification, with the corrected text then punched onto a new tape. It also supports direct text entry from a keyboard for creating new tapes.

The Editor operates in two distinct modes: Command mode, where typed input is interpreted as instructions, and Text mode, where input is treated as text to be inserted. A visual indicator (LINK light) on the PDP-7 console helps users differentiate between these modes. Commands are typically single letters preceded by zero, one, or two arguments, executed upon a carriage return. Special key functions (e.g., Carriage Return, Line Feed, Rub Out) provide additional operational control, such as deleting characters or printing lines. The Editor can handle both ASCII and FIODEC tape codes for input and output, with settings configurable via AC switches to manage aspects like tabulation, parity checking, and tape format.

The command repertoire is extensive, covering Input-Tape Operations (reading and skipping pages/lines), Editing (deleting, appending, inserting, changing text, external insertions, individual character corrections, and clearing the buffer), Text Examination (printing parts or all of the buffer, with options to suppress comments or find symbolic locations), and Punching Operations (outputting edited text, form feeds, and tape duplication). The manual emphasizes the PDP-7's compatibility with the PDP-4's existing program library, providing users with a mature and field-tested programming system and continuous development advantages.